Merge branch 'master' into bael-1908

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "testgitrepo"]
-	path = testgitrepo
-	url = /home/prd/Development/projects/idea/tutorials/spring-boot/src/main/resources/testgitrepo/

algorithms/README.md

@@ -22,3 +22,6 @@
 - [Displaying Money Amounts in Words](http://www.baeldung.com/java-money-into-words)
 - [A Collaborative Filtering Recommendation System in Java](http://www.baeldung.com/java-collaborative-filtering-recommendations)
 - [Find All Pairs of Numbers in an Array That Add Up to a Given Sum](http://www.baeldung.com/java-algorithm-number-pairs-sum)
+- [Converting Between Roman and Arabic Numerals in Java](http://www.baeldung.com/java-convert-roman-arabic)
+- [Practical Java Examples of the Big O Notation](http://www.baeldung.com/java-algorithm-complexity)
+- [Find the Middle Element of a Linked List](http://www.baeldung.com/java-linked-list-middle-element)

algorithms/src/main/java/com/baeldung/algorithms/mcts/montecarlo/MonteCarloTreeSearch.java

@@ -10,7 +10,7 @@ public class MonteCarloTreeSearch {
 
     private static final int WIN_SCORE = 10;
     private int level;
-    private int oponent;
+    private int opponent;
 
     public MonteCarloTreeSearch() {
         this.level = 3;
@@ -32,11 +32,11 @@ public class MonteCarloTreeSearch {
         long start = System.currentTimeMillis();
         long end = start + 60 * getMillisForCurrentLevel();
 
-        oponent = 3 - playerNo;
+        opponent = 3 - playerNo;
         Tree tree = new Tree();
         Node rootNode = tree.getRoot();
         rootNode.getState().setBoard(board);
-        rootNode.getState().setPlayerNo(oponent);
+        rootNode.getState().setPlayerNo(opponent);
 
         while (System.currentTimeMillis() < end) {
             // Phase 1 - Selection
@@ -93,7 +93,7 @@ public class MonteCarloTreeSearch {
         State tempState = tempNode.getState();
         int boardStatus = tempState.getBoard().checkStatus();
 
-        if (boardStatus == oponent) {
+        if (boardStatus == opponent) {
             tempNode.getParent().getState().setWinScore(Integer.MIN_VALUE);
             return boardStatus;
         }

algorithms/src/main/java/com/baeldung/algorithms/romannumerals/RomanArabicConverter.java

@@ -0,0 +1,52 @@
+package com.baeldung.algorithms.romannumerals;
+
+import java.util.List;
+
+class RomanArabicConverter {
+
+    public static int romanToArabic(String input) {
+        String romanNumeral = input.toUpperCase();
+        int result = 0;
+        
+        List<RomanNumeral> romanNumerals = RomanNumeral.getReverseSortedValues();
+
+        int i = 0;
+
+        while ((romanNumeral.length() > 0) && (i < romanNumerals.size())) {
+            RomanNumeral symbol = romanNumerals.get(i);
+            if (romanNumeral.startsWith(symbol.name())) {
+                result += symbol.getValue();
+                romanNumeral = romanNumeral.substring(symbol.name().length());
+            } else {
+                i++;
+            }
+        }
+        if (romanNumeral.length() > 0) {
+            throw new IllegalArgumentException(input + " cannot be converted to a Roman Numeral");
+        }
+
+        return result;
+    }
+
+    public static String arabicToRoman(int number) {
+        if ((number <= 0) || (number > 4000)) {
+            throw new IllegalArgumentException(number + " is not in range (0,4000]");
+        }
+
+        List<RomanNumeral> romanNumerals = RomanNumeral.getReverseSortedValues();
+
+        int i = 0;
+        StringBuilder sb = new StringBuilder();
+
+        while (number > 0 && i < romanNumerals.size()) {
+            RomanNumeral currentSymbol = romanNumerals.get(i);
+            if (currentSymbol.getValue() <= number) {
+                sb.append(currentSymbol.name());
+                number -= currentSymbol.getValue();
+            } else {
+                i++;
+            }
+        }
+        return sb.toString();
+    }
+}

algorithms/src/main/java/com/baeldung/algorithms/romannumerals/RomanNumeral.java

@@ -0,0 +1,26 @@
+package com.baeldung.algorithms.romannumerals;
+
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+enum RomanNumeral {
+    I(1), IV(4), V(5), IX(9), X(10), XL(40), L(50), XC(90), C(100), CD(400), D(500), CM(900), M(1000);
+
+    private int value;
+
+    RomanNumeral(int value) {
+        this.value = value;
+    }
+
+    public int getValue() {
+        return value;
+    }
+    
+    public static List<RomanNumeral> getReverseSortedValues() {
+        return Arrays.stream(values())
+          .sorted(Comparator.comparing((RomanNumeral e) -> e.value).reversed())
+          .collect(Collectors.toList());
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/romannumerals/RomanArabicConverterUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.algorithms.romannumerals;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class RomanArabicConverterUnitTest {
+
+    @Test
+    public void given2018Roman_WhenConvertingToArabic_ThenReturn2018() {
+
+        String roman2018 = "MMXVIII";
+
+        int result = RomanArabicConverter.romanToArabic(roman2018);
+
+        assertThat(result).isEqualTo(2018);
+    }
+
+    @Test
+    public void given1999Arabic_WhenConvertingToRoman_ThenReturnMCMXCIX() {
+
+        int arabic1999 = 1999;
+
+        String result = RomanArabicConverter.arabicToRoman(arabic1999);
+
+        assertThat(result).isEqualTo("MCMXCIX");
+    }
+
+}

antlr/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles: 
+
+- [Java with ANTLR](http://www.baeldung.com/java-antlr)

apache-meecrowave/pom.xml

@@ -0,0 +1,57 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>apache-meecrowave</artifactId>
+    <version>0.0.1</version>
+    <name>apache-meecrowave</name>
+    <description>A sample REST API application with Meecrowave</description>
+
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+    <dependencies>
+        <!-- https://mvnrepository.com/artifact/org.apache.meecrowave/meecrowave-core -->
+        <dependency>
+            <groupId>org.apache.meecrowave</groupId>
+            <artifactId>meecrowave-core</artifactId>
+            <version>1.2.1</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.meecrowave/meecrowave-jpa -->
+        <dependency>
+            <groupId>org.apache.meecrowave</groupId>
+            <artifactId>meecrowave-jpa</artifactId>
+            <version>1.2.1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.squareup.okhttp3</groupId>
+            <artifactId>okhttp</artifactId>
+            <version>3.10.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.meecrowave</groupId>
+            <artifactId>meecrowave-junit</artifactId>
+            <version>1.2.0</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/junit/junit -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.10</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.meecrowave</groupId>
+                <artifactId>meecrowave-maven-plugin</artifactId>
+                <version>1.2.1</version>
+            </plugin>
+        </plugins>
+    </build>
+</project>

apache-meecrowave/src/main/java/com/baeldung/meecrowave/Article.java

@@ -0,0 +1,30 @@
+package com.baeldung.meecrowave;
+
+public class Article {
+    private String name;
+    private String author;
+
+    public Article() {
+    }
+
+    public Article(String name, String author) {
+        this.author = author;
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+}

apache-meecrowave/src/main/java/com/baeldung/meecrowave/ArticleEndpoints.java

@@ -0,0 +1,32 @@
+package com.baeldung.meecrowave;
+
+import javax.enterprise.context.RequestScoped;
+import javax.inject.Inject;
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.core.Response.Status;
+
+@RequestScoped
+@Path("article")
+public class ArticleEndpoints {
+
+    @Inject
+    ArticleService articleService;
+
+    @GET
+    public Response getArticle() {
+        return Response.ok()
+            .entity(new Article("name", "author"))
+            .build();
+
+    }
+
+    @POST
+    public Response createArticle(Article article) {
+        return Response.status(Status.CREATED)
+            .entity(articleService.createArticle(article))
+            .build();
+    }
+}

apache-meecrowave/src/main/java/com/baeldung/meecrowave/ArticleService.java

@@ -0,0 +1,10 @@
+package com.baeldung.meecrowave;
+
+import javax.enterprise.context.ApplicationScoped;
+
+@ApplicationScoped
+public class ArticleService {
+    public Article createArticle(Article article) {
+        return article;
+    }
+}

apache-meecrowave/src/main/java/com/baeldung/meecrowave/Server.java

@@ -0,0 +1,16 @@
+package com.baeldung.meecrowave;
+
+import org.apache.meecrowave.Meecrowave;
+
+public class Server {
+    public static void main(String[] args) {
+        final Meecrowave.Builder builder = new Meecrowave.Builder();
+        builder.setScanningPackageIncludes("com.baeldung.meecrowave");
+        builder.setJaxrsMapping("/api/*");
+        builder.setJsonpPrettify(true);
+
+        try (Meecrowave meecrowave = new Meecrowave(builder)) {
+            meecrowave.bake().await();
+        }
+    }
+}

apache-meecrowave/src/test/java/com/baeldung/meecrowave/ArticleEndpointsTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.meecrowave;
+
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+
+import org.apache.meecrowave.Meecrowave;
+import org.apache.meecrowave.junit.MonoMeecrowave;
+import org.apache.meecrowave.testing.ConfigurationInject;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+
+@RunWith(MonoMeecrowave.Runner.class)
+public class ArticleEndpointsTest {
+    
+    @ConfigurationInject
+    private Meecrowave.Builder config;
+    private static OkHttpClient client;
+    
+    @BeforeClass
+    public static void setup() {
+        client = new OkHttpClient();
+    }
+    
+   @Test
+    public void whenRetunedArticle_thenCorrect() throws IOException {
+        final String base = "http://localhost:"+config.getHttpPort();
+        
+        Request request = new Request.Builder()
+          .url(base+"/article")
+          .build();
+        Response response = client.newCall(request).execute();
+        assertEquals(200,  response.code());
+    }
+}

apache-solrj/src/test/java/com/baeldung/solrjava/SolrJavaLiveTest.java

@@ -12,7 +12,7 @@ import org.apache.solr.common.SolrDocumentList;
 import org.junit.Before;
 import org.junit.Test;
 
-public class SolrJavaIntegrationTest {
+public class SolrJavaLiveTest {
 
     private SolrJavaIntegration solrJavaIntegration;
 

aws-lambda/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles: 
+- [Using AWS Lambda with API Gateway](http://www.baeldung.com/aws-lambda-api-gateway)
+- [Introduction to AWS Serverless Application Model](http://www.baeldung.com/aws-serverless)

aws-lambda/sam-templates/template-implicit.yaml

@@ -0,0 +1,60 @@
+AWSTemplateFormatVersion: '2010-09-09'
+Transform: 'AWS::Serverless-2016-10-31'
+Description: Baeldung Serverless Application Model Example with Implicit API Definition
+Globals:
+  Api:
+    EndpointConfiguration: REGIONAL
+    Name: "TestAPI"
+Resources:
+  PersonTable:
+    Type: AWS::Serverless::SimpleTable
+    Properties:
+      PrimaryKey:
+          Name: id
+          Type: Number
+      TableName: Person
+  StorePersonFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: com.baeldung.lambda.apigateway.APIDemoHandler::handleRequest
+      Runtime: java8
+      Timeout: 15
+      MemorySize: 512
+      CodeUri: ../target/aws-lambda-0.1.0-SNAPSHOT.jar
+      Policies:
+        - DynamoDBCrudPolicy:
+            TableName: !Ref PersonTable
+      Environment:
+        Variables:
+          TABLE_NAME: !Ref PersonTable
+      Events:
+        StoreApi:
+          Type: Api
+          Properties:
+            Path: /persons
+            Method: PUT
+  GetPersonByHTTPParamFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: com.baeldung.lambda.apigateway.APIDemoHandler::handleGetByParam
+      Runtime: java8
+      Timeout: 15
+      MemorySize: 512
+      CodeUri: ../target/aws-lambda-0.1.0-SNAPSHOT.jar
+      Policies:
+        - DynamoDBReadPolicy:
+            TableName: !Ref PersonTable
+      Environment:
+        Variables:
+          TABLE_NAME: !Ref PersonTable
+      Events:
+        GetByPathApi:
+          Type: Api
+          Properties:
+            Path: /persons/{id}
+            Method: GET
+        GetByQueryApi:
+          Type: Api
+          Properties:
+            Path: /persons
+            Method: GET

aws-lambda/sam-templates/template-inline-swagger.yaml

@@ -0,0 +1,112 @@
+AWSTemplateFormatVersion: '2010-09-09'
+Transform: 'AWS::Serverless-2016-10-31'
+Description: Baeldung Serverless Application Model Example with Inline Swagger API Definition
+Resources:
+  PersonTable:
+    Type: AWS::Serverless::SimpleTable
+    Properties:
+      PrimaryKey:
+          Name: id
+          Type: Number
+      TableName: Person
+  StorePersonFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: com.baeldung.lambda.apigateway.APIDemoHandler::handleRequest
+      Runtime: java8
+      Timeout: 15
+      MemorySize: 512
+      CodeUri: ../target/aws-lambda-0.1.0-SNAPSHOT.jar
+      Policies:
+        - DynamoDBCrudPolicy:
+            TableName: !Ref PersonTable
+      Environment:
+        Variables:
+          TABLE_NAME: !Ref PersonTable
+      Events:
+        StoreApi:
+          Type: Api
+          Properties:
+            Path: /persons
+            Method: PUT
+            RestApiId:
+                Ref: MyApi
+  GetPersonByHTTPParamFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: com.baeldung.lambda.apigateway.APIDemoHandler::handleGetByParam
+      Runtime: java8
+      Timeout: 15
+      MemorySize: 512
+      CodeUri: ../target/aws-lambda-0.1.0-SNAPSHOT.jar
+      Policies:
+        - DynamoDBReadPolicy:
+            TableName: !Ref PersonTable
+      Environment:
+        Variables:
+          TABLE_NAME: !Ref PersonTable
+      Events:
+        GetByPathApi:
+          Type: Api
+          Properties:
+            Path: /persons/{id}
+            Method: GET
+            RestApiId:
+                Ref: MyApi
+        GetByQueryApi:
+          Type: Api
+          Properties:
+            Path: /persons
+            Method: GET
+            RestApiId:
+                Ref: MyApi
+  MyApi:
+    Type: AWS::Serverless::Api
+    Properties:
+      StageName: test
+      EndpointConfiguration: REGIONAL
+      DefinitionBody:
+        swagger: "2.0"
+        info:
+          title: "TestAPI"
+        paths:
+          /persons:
+            get:
+              parameters:
+              - name: "id"
+                in: "query"
+                required: true
+                type: "string"
+              x-amazon-apigateway-request-validator: "Validate query string parameters and\
+                \ headers"
+              x-amazon-apigateway-integration:
+                uri:
+                  Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetPersonByHTTPParamFunction.Arn}/invocations
+                responses: {}
+                httpMethod: "POST"
+                type: "aws_proxy"
+            put:
+              x-amazon-apigateway-integration:
+                uri:
+                  Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${StorePersonFunction.Arn}/invocations
+                responses: {}
+                httpMethod: "POST"
+                type: "aws_proxy"
+          /persons/{id}:
+            get:
+              parameters:
+              - name: "id"
+                in: "path"
+                required: true
+                type: "string"
+              responses: {}
+              x-amazon-apigateway-integration:
+                uri:
+                  Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetPersonByHTTPParamFunction.Arn}/invocations
+                responses: {}
+                httpMethod: "POST"
+                type: "aws_proxy"
+        x-amazon-apigateway-request-validators:
+          Validate query string parameters and headers:
+            validateRequestParameters: true
+            validateRequestBody: false

aws-lambda/src/main/java/com/baeldung/lambda/apigateway/APIDemoHandler.java

@@ -15,152 +15,107 @@ import java.io.*;
 
 public class APIDemoHandler implements RequestStreamHandler {
 
-	private JSONParser parser = new JSONParser();
+    private JSONParser parser = new JSONParser();
-	private  static final String DYNAMODB_TABLE_NAME = System.getenv("TABLE_NAME");
+    private static final String DYNAMODB_TABLE_NAME = System.getenv("TABLE_NAME");
 
-	@Override
+    @Override
-	public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
+    public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
 
-		BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
+        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
-		JSONObject responseJson = new JSONObject();
+        JSONObject responseJson = new JSONObject();
 
-		AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
+        AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
-		DynamoDB dynamoDb = new DynamoDB(client);
+        DynamoDB dynamoDb = new DynamoDB(client);
 
-		try {
+        try {
-			JSONObject event = (JSONObject) parser.parse(reader);
+            JSONObject event = (JSONObject) parser.parse(reader);
 
-			if (event.get("body") != null) {
+            if (event.get("body") != null) {
 
-				Person person = new Person((String) event.get("body"));
+                Person person = new Person((String) event.get("body"));
 
-				dynamoDb.getTable(DYNAMODB_TABLE_NAME)
+                dynamoDb.getTable(DYNAMODB_TABLE_NAME)
-						.putItem(new PutItemSpec().withItem(new Item().withNumber("id", person.getId())
+                    .putItem(new PutItemSpec().withItem(new Item().withNumber("id", person.getId())
-								.withString("firstName", person.getFirstName())
+                        .withString("name", person.getName())));
-								.withString("lastName", person.getLastName()).withNumber("age", person.getAge())
+            }
-								.withString("address", person.getAddress())));
-			}
 
-			JSONObject responseBody = new JSONObject();
+            JSONObject responseBody = new JSONObject();
-			responseBody.put("message", "New item created");
+            responseBody.put("message", "New item created");
 
-			JSONObject headerJson = new JSONObject();
+            JSONObject headerJson = new JSONObject();
-			headerJson.put("x-custom-header", "my custom header value");
+            headerJson.put("x-custom-header", "my custom header value");
 
-			responseJson.put("statusCode", 200);
+            responseJson.put("statusCode", 200);
-			responseJson.put("headers", headerJson);
+            responseJson.put("headers", headerJson);
-			responseJson.put("body", responseBody.toString());
+            responseJson.put("body", responseBody.toString());
 
-		} catch (ParseException pex) {
+        } catch (ParseException pex) {
-			responseJson.put("statusCode", 400);
+            responseJson.put("statusCode", 400);
-			responseJson.put("exception", pex);
+            responseJson.put("exception", pex);
-		}
+        }
 
-		OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
+        OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
-		writer.write(responseJson.toString());
+        writer.write(responseJson.toString());
-		writer.close();
+        writer.close();
-	}
+    }
 
-	public void handleGetByPathParam(InputStream inputStream, OutputStream outputStream, Context context)
+    public void handleGetByParam(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
-			throws IOException {
 
-		BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
+        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
-		JSONObject responseJson = new JSONObject();
+        JSONObject responseJson = new JSONObject();
 
-		AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
+        AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
-		DynamoDB dynamoDb = new DynamoDB(client);
+        DynamoDB dynamoDb = new DynamoDB(client);
 
-		Item result = null;
+        Item result = null;
-		try {
+        try {
-			JSONObject event = (JSONObject) parser.parse(reader);
+            JSONObject event = (JSONObject) parser.parse(reader);
-			JSONObject responseBody = new JSONObject();
+            JSONObject responseBody = new JSONObject();
 
-			if (event.get("pathParameters") != null) {
+            if (event.get("pathParameters") != null) {
 
-				JSONObject pps = (JSONObject) event.get("pathParameters");
+                JSONObject pps = (JSONObject) event.get("pathParameters");
-				if (pps.get("id") != null) {
+                if (pps.get("id") != null) {
 
-					int id = Integer.parseInt((String) pps.get("id"));
+                    int id = Integer.parseInt((String) pps.get("id"));
-					result = dynamoDb.getTable(DYNAMODB_TABLE_NAME).getItem("id", id);
+                    result = dynamoDb.getTable(DYNAMODB_TABLE_NAME)
-				}
+                        .getItem("id", id);
+                }
 
-			}
+            } else if (event.get("queryStringParameters") != null) {
-			if (result != null) {
 
-				Person person = new Person(result.toJSON());
+                JSONObject qps = (JSONObject) event.get("queryStringParameters");
-				responseBody.put("Person", person);
+                if (qps.get("id") != null) {
-				responseJson.put("statusCode", 200);
-			} else {
 
-				responseBody.put("message", "No item found");
+                    int id = Integer.parseInt((String) qps.get("id"));
-				responseJson.put("statusCode", 404);
+                    result = dynamoDb.getTable(DYNAMODB_TABLE_NAME)
-			}
+                        .getItem("id", id);
+                }
+            }
+            if (result != null) {
 
-			JSONObject headerJson = new JSONObject();
+                Person person = new Person(result.toJSON());
-			headerJson.put("x-custom-header", "my custom header value");
+                responseBody.put("Person", person);
+                responseJson.put("statusCode", 200);
+            } else {
 
-			responseJson.put("headers", headerJson);
+                responseBody.put("message", "No item found");
-			responseJson.put("body", responseBody.toString());
+                responseJson.put("statusCode", 404);
+            }
 
-		} catch (ParseException pex) {
+            JSONObject headerJson = new JSONObject();
-			responseJson.put("statusCode", 400);
+            headerJson.put("x-custom-header", "my custom header value");
-			responseJson.put("exception", pex);
-		}
 
-		OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
+            responseJson.put("headers", headerJson);
-		writer.write(responseJson.toString());
+            responseJson.put("body", responseBody.toString());
-		writer.close();
-	}
 
-	public void handleGetByQueryParam(InputStream inputStream, OutputStream outputStream, Context context)
+        } catch (ParseException pex) {
-			throws IOException {
+            responseJson.put("statusCode", 400);
-
+            responseJson.put("exception", pex);
-		BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
+        }
-		JSONObject responseJson = new JSONObject();
-
-		AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();
-		DynamoDB dynamoDb = new DynamoDB(client);
-
-		Item result = null;
-		try {
-			JSONObject event = (JSONObject) parser.parse(reader);
-			JSONObject responseBody = new JSONObject();
-
-			if (event.get("queryStringParameters") != null) {
-
-				JSONObject qps = (JSONObject) event.get("queryStringParameters");
-				if (qps.get("id") != null) {
-
-					int id = Integer.parseInt((String) qps.get("id"));
-					result = dynamoDb.getTable(DYNAMODB_TABLE_NAME).getItem("id", id);
-				}
-			}
-
-			if (result != null) {
-
-				Person person = new Person(result.toJSON());
-				responseBody.put("Person", person);
-				responseJson.put("statusCode", 200);
-			} else {
-
-				responseBody.put("message", "No item found");
-				responseJson.put("statusCode", 404);
-			}
-
-			JSONObject headerJson = new JSONObject();
-			headerJson.put("x-custom-header", "my custom header value");
-
-			responseJson.put("headers", headerJson);
-			responseJson.put("body", responseBody.toString());
-
-		} catch (ParseException pex) {
-			responseJson.put("statusCode", 400);
-			responseJson.put("exception", pex);
-		}
-
-		OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
-		writer.write(responseJson.toString());
-		writer.close();
-	}
 
+        OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
+        writer.write(responseJson.toString());
+        writer.close();
+    }
 }

aws-lambda/src/main/java/com/baeldung/lambda/apigateway/model/Person.java

@@ -5,64 +5,34 @@ import com.google.gson.GsonBuilder;
 
 public class Person {
 
-	private int id;
+    private int id;
-	private String firstName;
+    private String name;
-	private String lastName;
-	private int age;
-	private String address;
 
-	public Person(String json) {
+    public Person(String json) {
-		Gson gson = new Gson();
+        Gson gson = new Gson();
-		Person request = gson.fromJson(json, Person.class);
+        Person request = gson.fromJson(json, Person.class);
-		this.id = request.getId();
+        this.id = request.getId();
-		this.firstName = request.getFirstName();
+        this.name = request.getName();
-		this.lastName = request.getLastName();
+    }
-		this.age = request.getAge();
-		this.address = request.getAddress();
-	}
 
-	public String toString() {
+    public String toString() {
-		final Gson gson = new GsonBuilder().setPrettyPrinting().create();
+        final Gson gson = new GsonBuilder().setPrettyPrinting().create();
-		return gson.toJson(this);
+        return gson.toJson(this);
-	}
+    }
 
-	public int getId() {
+    public int getId() {
-		return id;
+        return id;
-	}
+    }
 
-	public void setId(int id) {
+    public void setId(int id) {
-		this.id = id;
+        this.id = id;
-	}
+    }
 
-	public String getFirstName() {
+    public String getName() {
-		return firstName;
+        return name;
-	}
+    }
 
-	public void setFirstName(String firstName) {
+    public void setName(String name) {
-		this.firstName = firstName;
+        this.name = name;
-	}
+    }
-
-	public String getLastName() {
-		return lastName;
-	}
-
-	public void setLastName(String lastName) {
-		this.lastName = lastName;
-	}
-
-	public int getAge() {
-		return age;
-	}
-
-	public void setAge(int age) {
-		this.age = age;
-	}
-
-	public String getAddress() {
-		return address;
-	}
-
-	public void setAddress(String address) {
-		this.address = address;
-	}
 }

baeldung-pmd-rules.xml

@@ -3,7 +3,7 @@
 	xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0 http://pmd.sf.net/ruleset_xml_schema.xsd" 
 	xsi:noNamespaceSchemaLocation="http://pmd.sf.net/ruleset_xml_schema.xsd">
 	<description>Baeldung custom PMD rules</description>
-	<rule name="UnitTestMustFollowNamingConventionRule" message="Test class name doesn't follow the naming convention" class="org.baeldung.pmd.UnitTestNamingConventionRule">
+	<rule name="UnitTestMustFollowNamingConventionRule" message="Unit test class names need to end in 'UnitTest', integration tests with 'IntegrationTest', etc " class="org.baeldung.pmd.UnitTestNamingConventionRule">
 		<description>Test does not follow Baeldung naming convention</description>
 		<priority>3</priority>
 	</rule>

cdi/README.md

@@ -1,2 +1,3 @@
 ### Relevant Articles:
 - [CDI Interceptor vs Spring AspectJ](http://www.baeldung.com/cdi-interceptor-vs-spring-aspectj)
+- [An Introduction to CDI (Contexts and Dependency Injection) in Java](http://www.baeldung.com/java-ee-cdi)

core-java-8/README.md

@@ -54,3 +54,5 @@
 - [An Introduction to Java.util.Hashtable Class](http://www.baeldung.com/java-hash-table)
 - [Method Parameter Reflection in Java](http://www.baeldung.com/java-parameter-reflection)
 - [Java 8 Unsigned Arithmetic Support](http://www.baeldung.com/java-unsigned-arithmetic)
+- [How to Get the Start and the End of a Day using Java](http://www.baeldung.com/java-day-start-end)
+- [Generalized Target-Type Inference in Java](http://www.baeldung.com/java-generalized-target-type-inference)

core-java-8/src/main/java/com/baeldung/datetime/AddHoursToDate.java

@@ -0,0 +1,54 @@
+package com.baeldung.datetime;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZonedDateTime;
+import java.time.temporal.ChronoUnit;
+import java.util.Calendar;
+import java.util.Date;
+
+import org.apache.commons.lang3.time.DateUtils;
+
+public class AddHoursToDate {
+
+    public Date addHoursToJavaUtilDate(Date date, int hours) {
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTime(date);
+        calendar.add(Calendar.HOUR_OF_DAY, hours);
+        return calendar.getTime();
+    }
+
+    public Date addHoursToDateUsingInstant(Date date, int hours) {
+        return Date.from(date.toInstant()
+            .plus(Duration.ofHours(hours)));
+    }
+
+    public LocalDateTime addHoursToLocalDateTime(LocalDateTime localDateTime, int hours) {
+        return localDateTime.plusHours(hours);
+    }
+
+    public LocalDateTime subtractHoursToLocalDateTime(LocalDateTime localDateTime, int hours) {
+        return localDateTime.minusHours(hours);
+    }
+
+    public ZonedDateTime addHoursToZonedDateTime(ZonedDateTime zonedDateTime, int hours) {
+        return zonedDateTime.plusHours(hours);
+    }
+
+    public ZonedDateTime subtractHoursToZonedDateTime(ZonedDateTime zonedDateTime, int hours) {
+        return zonedDateTime.minusHours(hours);
+    }
+
+    public Instant addHoursToInstant(Instant instant, int hours) {
+        return instant.plus(hours, ChronoUnit.HOURS);
+    }
+
+    public Instant subtractHoursToInstant(Instant instant, int hours) {
+        return instant.minus(hours, ChronoUnit.HOURS);
+    }
+
+    public Date addHoursWithApacheCommons(Date date, int hours) {
+        return DateUtils.addHours(date, hours);
+    }
+}

core-java-8/src/test/java/com/baeldung/datetime/AddHoursToDateUnitTest.java

@@ -0,0 +1,116 @@
+package com.baeldung.datetime;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.Month;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
+
+import org.junit.Test;
+
+public class AddHoursToDateUnitTest {
+
+    private final AddHoursToDate addHoursToDateObj = new AddHoursToDate();
+
+    @Test
+    public void givenJavaUtilDate_whenPositiveHours_thenAddHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 7, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursToJavaUtilDate(actualDate, 2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenNegativeHours_thenMinusHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 3, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursToJavaUtilDate(actualDate, -2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenUsingToInstantAndPostiveHours_thenAddHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 7, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursToDateUsingInstant(actualDate, 2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenUsingToInstantAndNegativeHours_thenAddHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 3, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursToDateUsingInstant(actualDate, -2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenLocalDateTime_whenUsingAddHoursToLocalDateTime_thenAddHours() {
+        LocalDateTime actualDateTime = LocalDateTime.of(2018, Month.JUNE, 25, 5, 0);
+        LocalDateTime expectedDateTime = LocalDateTime.of(2018, Month.JUNE, 25, 7, 0);
+
+        assertThat(addHoursToDateObj.addHoursToLocalDateTime(actualDateTime, 2)).isEqualTo(expectedDateTime);
+    }
+
+    @Test
+    public void givenLocalDateTime_whenUsingMinusHoursToLocalDateTime_thenMinusHours() {
+        LocalDateTime actualDateTime = LocalDateTime.of(2018, Month.JUNE, 25, 5, 0);
+        LocalDateTime expectedDateTime = LocalDateTime.of(2018, Month.JUNE, 25, 3, 0);
+
+        assertThat(addHoursToDateObj.subtractHoursToLocalDateTime(actualDateTime, 2)).isEqualTo(expectedDateTime);
+    }
+
+    @Test
+    public void givenZonedDateTime_whenUsingAddHoursToZonedDateTime_thenAddHours() {
+        ZonedDateTime actualZonedDateTime = ZonedDateTime.of(LocalDateTime.of(2018, Month.JUNE, 25, 5, 0), ZoneId.systemDefault());
+        ZonedDateTime expectedZonedDateTime = ZonedDateTime.of(LocalDateTime.of(2018, Month.JUNE, 25, 7, 0), ZoneId.systemDefault());
+
+        assertThat(addHoursToDateObj.addHoursToZonedDateTime(actualZonedDateTime, 2)).isEqualTo(expectedZonedDateTime);
+    }
+
+    @Test
+    public void givenZonedDateTime_whenUsingMinusHoursToZonedDateTime_thenMinusHours() {
+        ZonedDateTime actualZonedDateTime = ZonedDateTime.of(LocalDateTime.of(2018, Month.JUNE, 25, 5, 0), ZoneId.systemDefault());
+        ZonedDateTime expectedZonedDateTime = ZonedDateTime.of(LocalDateTime.of(2018, Month.JUNE, 25, 3, 0), ZoneId.systemDefault());
+
+        assertThat(addHoursToDateObj.subtractHoursToZonedDateTime(actualZonedDateTime, 2)).isEqualTo(expectedZonedDateTime);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenUsingPositiveHrsAndAddHoursWithApacheCommons_thenAddHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 7, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursWithApacheCommons(actualDate, 2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenJavaUtilDate_whenUsingNegativeHrsAndAddHoursWithApacheCommons_thenMinusHours() {
+        Date actualDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 7, 0).getTime();
+        Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25, 5, 0).getTime();
+
+        assertThat(addHoursToDateObj.addHoursWithApacheCommons(actualDate, -2)).isEqualTo(expectedDate);
+    }
+
+    @Test
+    public void givenInstant_whenUsingAddHoursToInstant_thenAddHours() {
+        Instant actualValue = Instant.parse("2018-06-25T05:12:35Z");
+        Instant expectedValue = Instant.parse("2018-06-25T07:12:35Z");
+
+        assertThat(addHoursToDateObj.addHoursToInstant(actualValue, 2)).isEqualTo(expectedValue);
+    }
+
+    @Test
+    public void givenInstant_whenUsingSubtractHoursToInstant_thenMinusHours() {
+        Instant actualValue = Instant.parse("2018-06-25T07:12:35Z");
+        Instant expectedValue = Instant.parse("2018-06-25T05:12:35Z");
+
+        assertThat(addHoursToDateObj.subtractHoursToInstant(actualValue, 2)).isEqualTo(expectedValue);
+    }
+
+}

core-java-8/src/test/java/com/baeldung/fileToBase64StringConversion/FileToBase64StringConversionUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.fileToBase64StringConversion;
+
+import static org.junit.Assert.assertTrue;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Base64;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.Test;
+
+public class FileToBase64StringConversionUnitTest {
+
+    private String inputFilePath = "test_image.jpg";
+    private String outputFilePath = "test_image_copy.jpg";
+
+    @Test
+    public void fileToBase64StringConversion() throws IOException {
+        //load file from /src/test/resources
+        ClassLoader classLoader = getClass().getClassLoader();
+        File inputFile = new File(classLoader
+          .getResource(inputFilePath)
+          .getFile());
+
+        byte[] fileContent = FileUtils.readFileToByteArray(inputFile);
+        String encodedString = Base64
+          .getEncoder()
+          .encodeToString(fileContent);
+
+        //create output file
+        File outputFile = new File(inputFile
+          .getParentFile()
+          .getAbsolutePath() + File.pathSeparator + outputFilePath);
+
+        // decode the string and write to file
+        byte[] decodedBytes = Base64
+          .getDecoder()
+          .decode(encodedString);
+        FileUtils.writeByteArrayToFile(outputFile, decodedBytes);
+
+        assertTrue(FileUtils.contentEquals(inputFile, outputFile));
+    }
+}

core-java-collections/src/main/java/com/baeldung/java/list/ReverseIterator.java

@@ -0,0 +1,80 @@
+package com.baeldung.java.list;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.ListIterator;
+
+import org.apache.commons.collections4.iterators.ReverseListIterator;
+
+import com.google.common.collect.Lists;
+
+/**
+ * Provides methods for iterating backward over a list.
+ */
+public class ReverseIterator {
+
+    /**
+     * Iterate using the for loop.
+     *
+     * @param list the list
+     */
+    public void iterateUsingForLoop(final List<String> list) {
+
+        for (int i = list.size(); i-- > 0; ) {
+            System.out.println(list.get(i));
+        }
+    }
+
+    /**
+     * Iterate using the Java {@link ListIterator}.
+     *
+     * @param list the list
+     */
+    public void iterateUsingListIterator(final List<String> list) {
+
+        final ListIterator listIterator = list.listIterator(list.size());
+        while (listIterator.hasPrevious()) {
+            System.out.println(listIterator.previous());
+        }
+    }
+
+    /**
+     * Iterate using Java {@link Collections} API.
+     *
+     * @param list the list
+     */
+    public void iterateUsingCollections(final List<String> list) {
+
+        Collections.reverse(list);
+        for (final String item : list) {
+            System.out.println(item);
+        }
+    }
+
+    /**
+     * Iterate using Apache Commons {@link ReverseListIterator}.
+     *
+     * @param list the list
+     */
+    public void iterateUsingApacheReverseListIterator(final List<String> list) {
+
+        final ReverseListIterator listIterator = new ReverseListIterator(list);
+        while (listIterator.hasNext()) {
+            System.out.println(listIterator.next());
+        }
+    }
+
+    /**
+     * Iterate using Guava {@link Lists} API.
+     *
+     * @param list the list
+     */
+    public void iterateUsingGuava(final List<String> list) {
+
+        final List<String> reversedList = Lists.reverse(list);
+        for (final String item : reversedList) {
+            System.out.println(item);
+        }
+    }
+
+}

core-java-collections/src/test/java/com/baeldung/java/list/ReverseIteratorUnitTest.java

@@ -0,0 +1,87 @@
+package com.baeldung.java.list;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.ListIterator;
+
+import org.apache.commons.collections4.iterators.ReverseListIterator;
+import org.apache.commons.lang3.StringUtils;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import com.google.common.collect.Lists;
+
+public class ReverseIteratorUnitTest {
+
+    private final ReverseIterator reverseIterator = new ReverseIterator();
+
+    private List<String> list;
+
+    private final String originalString = "ABCDE";
+
+    @BeforeEach
+    void setUp() {
+
+        list = Lists.newArrayList("A", "B", "C", "D", "E");
+    }
+
+    @Test
+    void whenIteratingUsingForLoop_thenCorrect() {
+
+        String reverseString = "";
+        for (int i = list.size(); i-- > 0; ) {
+            reverseString += list.get(i);
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+    }
+
+    @Test
+    void whenIteratingUsingListIterator_thenCorrect() {
+
+        String reverseString = "";
+        final ListIterator listIterator = list.listIterator(list.size());
+        while (listIterator.hasPrevious()) {
+            reverseString += listIterator.previous();
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+    }
+
+    @Test
+    void whenIteratingUsingCollections_thenCorrect() {
+
+        String reverseString = "";
+        Collections.reverse(list);
+        for (final String item : list) {
+            reverseString += item;
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+
+        assertEquals("E", list.get(0));
+    }
+
+    @Test
+    void whenIteratingUsingApacheReverseListIterator_thenCorrect() {
+
+        String reverseString = "";
+        final ReverseListIterator listIterator = new ReverseListIterator(list);
+        while (listIterator.hasNext()) {
+            reverseString += listIterator.next();
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+    }
+
+    @Test
+    void whenIteratingUsingGuava_thenCorrect() {
+
+        String reverseString = "";
+        final List<String> reversedList = Lists.reverse(list);
+        for (final String item : reversedList) {
+            reverseString += item;
+        }
+        assertEquals(reverseString, StringUtils.reverse(originalString));
+
+        assertEquals("A", list.get(0));
+    }
+}

core-java-io/src/main/java/com/baeldung/symlink/SymLinkExample.java

@@ -0,0 +1,54 @@
+package com.baeldung.symlink;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.DirectoryStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import static java.nio.file.StandardOpenOption.*;
+import java.util.stream.IntStream;
+
+public class SymLinkExample {
+
+    public void createSymbolicLink(Path link, Path target) throws IOException {
+        if (Files.exists(link)) {
+            Files.delete(link);
+        }
+        Files.createSymbolicLink(link, target);
+    }
+
+    public void createHardLink(Path link, Path target) throws IOException {
+        if (Files.exists(link)) {
+            Files.delete(link);
+        }
+        Files.createLink(link, target);
+    }
+
+    public Path createTextFile() throws IOException {
+        byte[] content = IntStream.range(0, 10000)
+            .mapToObj(i -> i + System.lineSeparator())
+            .reduce("", String::concat)
+            .getBytes(StandardCharsets.UTF_8);
+        Path filePath = Paths.get(".", "target_link.txt");
+        Files.write(filePath, content, CREATE, TRUNCATE_EXISTING);
+        return filePath;
+    }
+
+    public void printLinkFiles(Path path) throws IOException {
+        try (DirectoryStream<Path> stream = Files.newDirectoryStream(path)) {
+            for (Path file : stream) {
+                if (Files.isDirectory(file)) {
+                    printLinkFiles(file);
+                } else if (Files.isSymbolicLink(file)) {
+                    System.out.format("File link '%s' with target '%s'%n", file, Files.readSymbolicLink(file));
+                }
+            }
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        new SymLinkExample().printLinkFiles(Paths.get("."));
+    }
+
+}

core-java-io/src/test/java/com/baeldung/symlink/SymLinkExampleUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.symlink;
+
+import static org.junit.Assert.*;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import org.junit.Test;
+
+public class SymLinkExampleUnitTest {
+
+    @Test
+    public void whenUsingFiles_thenCreateSymbolicLink() throws IOException {
+        SymLinkExample example = new SymLinkExample();
+        Path filePath = example.createTextFile();
+        Path linkPath = Paths.get(".", "symbolic_link.txt");
+        example.createSymbolicLink(linkPath, filePath);
+        assertTrue(Files.isSymbolicLink(linkPath));
+    }
+
+    @Test
+    public void whenUsingFiles_thenCreateHardLink() throws IOException {
+        SymLinkExample example = new SymLinkExample();
+        Path filePath = example.createTextFile();
+        Path linkPath = Paths.get(".", "hard_link.txt");
+        example.createHardLink(linkPath, filePath);
+        assertFalse(Files.isSymbolicLink(linkPath));
+        assertEquals(filePath.toFile()
+            .length(),
+            linkPath.toFile()
+                .length());
+    }
+
+}

core-java-io/src/test/java/org/baeldung/java/io/JavaInputStreamToXUnitTest.java

@@ -14,8 +14,10 @@ import org.slf4j.LoggerFactory;
 import java.io.*;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Path;
 import java.nio.file.StandardCopyOption;
 import java.util.Scanner;
+import java.util.UUID;
 
 import static org.apache.commons.lang3.RandomStringUtils.randomAlphabetic;
 import static org.hamcrest.Matchers.equalTo;
@@ -112,6 +114,19 @@ public class JavaInputStreamToXUnitTest {
         assertThat(writer.toString(), equalTo(originalString));
     }
     
+    @Test
+    public final void givenUsingTempFile_whenConvertingAnInputStreamToAString_thenCorrect() throws IOException {
+        final String originalString = randomAlphabetic(DEFAULT_SIZE);
+        final InputStream inputStream = new ByteArrayInputStream(originalString.getBytes());
+
+        // When
+        Path tempFile = java.nio.file.Files.createTempDirectory("").resolve(UUID.randomUUID().toString() + ".tmp");
+        java.nio.file.Files.copy(inputStream, tempFile, StandardCopyOption.REPLACE_EXISTING);
+        String result = new String(java.nio.file.Files.readAllBytes(tempFile));
+
+        assertThat(result, equalTo(originalString));
+    }
+
     // tests - InputStream to byte[]
 
     @Test

core-java/README.md

@@ -160,3 +160,10 @@
 - [Guide to the super Java Keyword](http://www.baeldung.com/java-super)
 - [Guide to the this Java Keyword](http://www.baeldung.com/java-this)
 - [Jagged Arrays In Java](http://www.baeldung.com/java-jagged-arrays)
+- [Importance of Main Manifest Attribute in a Self-Executing JAR](http://www.baeldung.com/java-jar-executable-manifest-main-class)
+- [Extracting Year, Month and Day from Date in Java](http://www.baeldung.com/java-year-month-day)
+- [Get Date Without Time in Java](http://www.baeldung.com/java-date-without-time)
+- [Convert a String to Title Case](http://www.baeldung.com/java-string-title-case)
+- [How to Get the File Extension of a File in Java](http://www.baeldung.com/java-file-extension)
+- [Immutable Objects in Java](http://www.baeldung.com/java-immutable-object)
+- [Console I/O in Java](http://www.baeldung.com/java-console-input-output)

core-java/pom.xml

@@ -10,8 +10,8 @@
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>parent-java</artifactId>
-    	<version>0.0.1-SNAPSHOT</version>
+        <version>0.0.1-SNAPSHOT</version>
-    	<relativePath>../parent-java</relativePath>
+        <relativePath>../parent-java</relativePath>
     </parent>
 
     <dependencies>
@@ -197,12 +197,7 @@
             <groupId>javax.mail</groupId>
             <artifactId>mail</artifactId>
             <version>${javax.mail.version}</version>
-        </dependency>
+      </dependency>
-        <dependency>
-            <groupId>javax.mail</groupId>
-            <artifactId>mail</artifactId>
-            <version>1.5.0-b01</version>
-        </dependency>
         <dependency>
             <groupId>com.ibm.icu</groupId>
             <artifactId>icu4j</artifactId>
@@ -255,6 +250,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-jar-plugin</artifactId>
+                <version>${maven-jar-plugin.version}</version>
                 <configuration>
                     <archive>
                         <manifest>
@@ -293,6 +289,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
+                <version>${maven-shade-plugin.version}</version>
                 <executions>
                     <execution>
                         <goals>
@@ -314,6 +311,7 @@
             <plugin>
                 <groupId>com.jolira</groupId>
                 <artifactId>onejar-maven-plugin</artifactId>
+                <version>${onejar-maven-plugin.version}</version>
                 <executions>
                     <execution>
                         <configuration>
@@ -331,6 +329,7 @@
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
+                <version>${spring-boot-maven-plugin.version}</version>
                 <executions>
                     <execution>
                         <goals>
@@ -478,6 +477,10 @@
         <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
         <exec-maven-plugin.version>1.6.0</exec-maven-plugin.version>
         <javax.mail.version>1.5.0-b01</javax.mail.version>
+        <maven-jar-plugin.version>3.0.2</maven-jar-plugin.version>
+        <onejar-maven-plugin.version>1.4.4</onejar-maven-plugin.version>
+        <maven-shade-plugin.version>3.1.1</maven-shade-plugin.version>
+        <spring-boot-maven-plugin.version>2.0.3.RELEASE</spring-boot-maven-plugin.version>
         <icu4j.version>61.1</icu4j.version>
     </properties>
 

core-java/src/main/java/com/baeldung/console/ConsoleConsoleClass.java

@@ -0,0 +1,26 @@
+package com.baeldung.console;
+
+import java.io.Console;
+
+public class ConsoleConsoleClass {
+
+    public static void main(String[] args) {
+        Console console = System.console();
+
+        if (console == null) {
+            System.out.print("No console available");
+            return;
+        }
+
+        String progLanguauge = console.readLine("Enter your favourite programming language: ");
+        console.printf(progLanguauge + " is very interesting!");
+
+        char[] pass = console.readPassword("To finish, enter password: ");
+        
+        if ("BAELDUNG".equals(pass.toString().toUpperCase()))
+            console.printf("Good! Regards!");
+        else 
+            console.printf("Nice try. Regards.");
+
+    }
+}

core-java/src/main/java/com/baeldung/console/ConsoleScannerClass.java

@@ -0,0 +1,76 @@
+package com.baeldung.console;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Scanner;
+import java.util.regex.Pattern;
+
+public class ConsoleScannerClass {
+
+    public static void main(String[] args) {
+        System.out.println("Please enter your name and surname: ");
+
+        Scanner scanner = new Scanner(System.in);
+
+        String nameSurname = scanner.nextLine();
+
+        System.out.println("Please enter your gender: ");
+
+        char gender = scanner.next().charAt(0);
+
+        System.out.println("Please enter your age: ");
+
+        int age = scanner.nextInt();
+
+        System.out.println("Please enter your height in meters: ");
+
+        double height = scanner.nextDouble();
+
+        System.out.println(nameSurname + ", " + age + ", is a great " + (gender == 'm' ? "guy" : "girl") + " with " + height + " meters height" + " and " + (gender == 'm' ? "he" : "she") + " reads Baeldung.");
+
+        System.out.print("Have a good");
+        System.out.print(" one!");
+
+        System.out.println("\nPlease enter number of years of experience as a developer: ");
+
+        BufferedReader buffReader = new BufferedReader(new InputStreamReader(System.in));
+
+        int i = 0;
+
+        try {
+            i = Integer.parseInt(buffReader.readLine());
+        } catch (NumberFormatException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+        } catch (IOException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+        }
+
+        System.out.println("You are a " + (i > 5 ? "great" : "good") + " developer!");
+
+        int sum = 0, count = 0;
+
+        System.out.println("Please enter your college degrees. To finish, enter baeldung website url");
+
+        while (scanner.hasNextInt()) {
+            int nmbr = scanner.nextInt();
+            sum += nmbr;
+            count++;
+        }
+        int mean = sum / count;
+
+        System.out.println("Your average degree is " + mean);
+
+        if (scanner.hasNext(Pattern.compile("www.baeldung.com")))
+            System.out.println("Correct!");
+        else
+            System.out.println("Baeldung website url is www.baeldung.com");
+
+        if (scanner != null)
+            scanner.close();
+
+    }
+
+}

core-java/src/main/java/com/baeldung/customexception/FileManager.java

@@ -0,0 +1,43 @@
+package com.baeldung.customexception;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.Scanner;
+
+public class FileManager {
+
+    public static String getFirstLine(String fileName) throws IncorrectFileNameException {
+        try (Scanner file = new Scanner(new File(fileName))) {
+            if (file.hasNextLine()) {
+                return file.nextLine();
+            } else {
+                throw new IllegalArgumentException("Non readable file");
+            }
+        } catch (FileNotFoundException err) {
+            if (!isCorrectFileName(fileName)) {
+                throw new IncorrectFileNameException("Incorrect filename : " + fileName, err);
+            }
+            // Logging etc
+        } catch (IllegalArgumentException err) {
+            if (!containsExtension(fileName)) {
+                throw new IncorrectFileExtensionException("Filename does not contain extension : " + fileName, err);
+            }
+            // Other error cases and logging
+        }
+        return "Default First Line";
+    }
+
+    private static boolean containsExtension(String fileName) {
+        if (fileName.contains(".txt") || fileName.contains(".doc"))
+            return true;
+        return false;
+    }
+
+    private static boolean isCorrectFileName(String fileName) {
+        if (fileName.equals("wrongFileName.txt"))
+            return false;
+        else
+            return true;
+    }
+
+}

core-java/src/main/java/com/baeldung/customexception/IncorrectFileExtensionException.java

@@ -0,0 +1,9 @@
+package com.baeldung.customexception;
+
+public class IncorrectFileExtensionException extends RuntimeException{
+    private static final long serialVersionUID = 1L;
+
+    public IncorrectFileExtensionException(String errorMessage, Throwable err) {
+        super(errorMessage, err);
+    }
+}

core-java/src/main/java/com/baeldung/customexception/IncorrectFileNameException.java

@@ -0,0 +1,9 @@
+package com.baeldung.customexception;
+
+public class IncorrectFileNameException extends Exception {
+    private static final long serialVersionUID = 1L;
+    
+    public IncorrectFileNameException(String errorMessage, Throwable err) {
+        super(errorMessage, err);
+    }
+}

core-java/src/main/java/com/baeldung/encrypt/FileEncrypterDecrypter.java

@@ -0,0 +1,60 @@
+package com.baeldung.encrypt;
+
+import javax.crypto.*;
+import javax.crypto.spec.IvParameterSpec;
+import java.io.*;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+
+class FileEncrypterDecrypter {
+
+    private SecretKey secretKey;
+    private Cipher cipher;
+
+    FileEncrypterDecrypter(SecretKey secretKey, String cipher) throws NoSuchPaddingException, NoSuchAlgorithmException {
+        this.secretKey = secretKey;
+        this.cipher = Cipher.getInstance(cipher);
+    }
+
+    void encrypt(String content, String fileName) throws InvalidKeyException, IOException {
+        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
+        byte[] iv = cipher.getIV();
+
+        try (
+                FileOutputStream fileOut = new FileOutputStream(fileName);
+                CipherOutputStream cipherOut = new CipherOutputStream(fileOut, cipher)
+        ) {
+            fileOut.write(iv);
+            cipherOut.write(content.getBytes());
+        }
+
+    }
+
+    String decrypt(String fileName) throws InvalidAlgorithmParameterException, InvalidKeyException, IOException {
+
+        String content;
+
+        try (FileInputStream fileIn = new FileInputStream(fileName)) {
+            byte[] fileIv = new byte[16];
+            fileIn.read(fileIv);
+            cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(fileIv));
+
+            try (
+                    CipherInputStream cipherIn = new CipherInputStream(fileIn, cipher);
+                    InputStreamReader inputReader = new InputStreamReader(cipherIn);
+                    BufferedReader reader = new BufferedReader(inputReader)
+                ) {
+
+                StringBuilder sb = new StringBuilder();
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    sb.append(line);
+                }
+                content = sb.toString();
+            }
+
+        }
+        return content;
+    }
+}

core-java/src/main/java/com/baeldung/exceptions/Arithmetic.java

@@ -0,0 +1,20 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class Arithmetic {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(Arithmetic.class);
+
+    public static void main(String[] args) {
+
+        try {
+            int result = 30 / 0; // Trying to divide by zero
+        } catch (ArithmeticException e) {
+            LOGGER.error("ArithmeticException caught!");
+        }
+
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/ArrayIndexOutOfBounds.java

@@ -0,0 +1,24 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class ArrayIndexOutOfBounds {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(ArrayIndexOutOfBounds.class);
+
+    public static void main(String[] args) {
+
+        int[] nums = new int[] { 1, 2, 3 };
+
+        try {
+            int numFromNegativeIndex = nums[-1]; // Trying to access at negative index
+            int numFromGreaterIndex = nums[4]; // Trying to access at greater index
+            int numFromLengthIndex = nums[3]; // Trying to access at index equal to size of the array
+        } catch (ArrayIndexOutOfBoundsException e) {
+            LOGGER.error("ArrayIndexOutOfBoundsException caught");
+        }
+
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/ClassCast.java

@@ -0,0 +1,36 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+class Animal {
+
+}
+
+class Dog extends Animal {
+
+}
+
+class Lion extends Animal {
+
+}
+
+public class ClassCast {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(ClassCast.class);
+
+    public static void main(String[] args) {
+
+        try {
+            Animal animalOne = new Dog(); // At runtime the instance is dog
+            Dog bruno = (Dog) animalOne; // Downcasting
+
+            Animal animalTwo = new Lion(); // At runtime the instance is animal
+            Dog tommy = (Dog) animalTwo; // Downcasting
+        } catch (ClassCastException e) {
+            LOGGER.error("ClassCastException caught!");
+        }
+
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/FileNotFound.java

@@ -0,0 +1,25 @@
+package com.baeldung.exceptions;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileReader;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class FileNotFound {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(FileNotFound.class);
+    
+    public static void main(String[] args) {
+        
+        BufferedReader reader = null;
+        try {
+            reader = new BufferedReader(new FileReader(new File("/invalid/file/location")));
+        } catch (FileNotFoundException e) {
+            LOGGER.error("FileNotFoundException caught!");
+        }
+    }
+    
+}

core-java/src/main/java/com/baeldung/exceptions/GlobalExceptionHandler.java

@@ -0,0 +1,28 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class GlobalExceptionHandler {
+
+    public static void main(String[] args) {
+
+        Handler globalExceptionHandler = new Handler();
+        Thread.setDefaultUncaughtExceptionHandler(globalExceptionHandler);
+        new GlobalExceptionHandler().performArithmeticOperation(10, 0);
+    }
+
+    public int performArithmeticOperation(int num1, int num2) {
+        return num1/num2;
+    }
+
+}
+
+class Handler implements Thread.UncaughtExceptionHandler {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(Handler.class);
+
+    public void uncaughtException(Thread t, Throwable e) {
+        LOGGER.info("Unhandled exception caught!");
+    }
+}

core-java/src/main/java/com/baeldung/exceptions/IllegalArgument.java

@@ -0,0 +1,18 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class IllegalArgument {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(IllegalArgument.class);
+
+    public static void main(String[] args) {
+        try {
+            Thread.sleep(-1000);
+        } catch (InterruptedException e) {
+            LOGGER.error("IllegalArgumentException caught!");
+        }
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/IllegalState.java

@@ -0,0 +1,32 @@
+package com.baeldung.exceptions;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class IllegalState {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(IllegalState.class);
+
+    public static void main(String[] args) {
+
+        List<Integer> intList = new ArrayList<>();
+
+        for (int i = 0; i < 10; i++) {
+            intList.add(i);
+        }
+
+        Iterator<Integer> intListIterator = intList.iterator(); // Initialized with index at -1
+
+        try {
+            intListIterator.remove(); // IllegalStateException
+        } catch (IllegalStateException e) {
+            LOGGER.error("IllegalStateException caught!");
+        }
+
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/InterruptedExceptionExample.java

@@ -0,0 +1,28 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+class ChildThread extends Thread {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(ChildThread.class);
+
+    public void run() {
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            LOGGER.error("InterruptedException caught!");
+        }
+    }
+    
+}
+
+public class InterruptedExceptionExample {
+
+    public static void main(String[] args) throws InterruptedException {
+        ChildThread childThread = new ChildThread();
+        childThread.start();
+        childThread.interrupt();
+    }
+    
+}

core-java/src/main/java/com/baeldung/exceptions/MalformedURL.java

@@ -0,0 +1,25 @@
+package com.baeldung.exceptions;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class MalformedURL {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(MalformedURL.class);
+
+    public static void main(String[] args) {
+
+        URL baeldungURL = null;
+
+        try {
+            baeldungURL = new URL("malformedurl");
+        } catch (MalformedURLException e) {
+            LOGGER.error("MalformedURLException caught!");
+        }
+
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/NullPointer.java

@@ -0,0 +1,36 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class NullPointer {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(NullPointer.class);
+
+    public static void main(String[] args) {
+
+        Person personObj = null;
+
+        try {
+            String name = personObj.personName; // Accessing the field of a null object
+            personObj.personName = "Jon Doe"; // Modifying the field of a null object
+        } catch (NullPointerException e) {
+            LOGGER.error("NullPointerException caught!");
+        }
+
+    }
+}
+
+class Person {
+
+    public String personName;
+
+    public String getPersonName() {
+        return personName;
+    }
+
+    public void setPersonName(String personName) {
+        this.personName = personName;
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/NumberFormat.java

@@ -0,0 +1,23 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class NumberFormat {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(NumberFormat.class);
+
+    public static void main(String[] args) {
+
+        String str1 = "100ABCD";
+
+        try {
+            int x = Integer.parseInt(str1); // Converting string with inappropriate format
+            int y = Integer.valueOf(str1);
+        } catch (NumberFormatException e) {
+            LOGGER.error("NumberFormatException caught!");
+        }
+
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/ParseExceptionExample.java

@@ -0,0 +1,25 @@
+package com.baeldung.exceptions;
+
+import java.text.DateFormat;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class ParseExceptionExample {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(ParseExceptionExample.class);
+
+    public static void main(String[] args) {
+
+        DateFormat format = new SimpleDateFormat("MM, dd, yyyy");
+
+        try {
+            format.parse("01, , 2010");
+        } catch (ParseException e) {
+            LOGGER.error("ParseException caught!");
+        }
+    }
+
+}

core-java/src/main/java/com/baeldung/exceptions/StringIndexOutOfBounds.java

@@ -0,0 +1,23 @@
+package com.baeldung.exceptions;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class StringIndexOutOfBounds {
+
+    private static Logger LOGGER = LoggerFactory.getLogger(StringIndexOutOfBounds.class);
+    
+    public static void main(String[] args) {
+
+        String str = "Hello World";
+
+        try {
+            char charAtNegativeIndex = str.charAt(-1); // Trying to access at negative index
+            char charAtLengthIndex = str.charAt(11); // Trying to access at index equal to size of the string
+        } catch (StringIndexOutOfBoundsException e) {
+           LOGGER.error("StringIndexOutOfBoundsException caught");
+        }
+
+    }
+
+}

core-java/src/main/java/com/baeldung/gregorian/calendar/GregorianCalendarExample.java

@@ -0,0 +1,69 @@
+package com.baeldung.gregorian.calendar;
+
+import java.time.format.DateTimeFormatter;
+import java.util.Calendar;
+import java.util.Collections;
+import java.util.Date;
+import java.util.GregorianCalendar;
+import java.util.HashSet;
+import java.util.Locale;
+import java.util.Set;
+import java.util.TimeZone;
+
+import javax.xml.datatype.DatatypeConfigurationException;
+import javax.xml.datatype.DatatypeFactory;
+import javax.xml.datatype.XMLGregorianCalendar;
+
+public class GregorianCalendarExample {
+
+   
+    public Date setMonth(GregorianCalendar calendar, int amount) {
+        calendar.set(Calendar.MONTH, amount);
+        return calendar.getTime();
+    }
+
+   
+    public Date rollAdd(GregorianCalendar calendar, int amount) {
+        calendar.roll(GregorianCalendar.MONTH, amount);
+        return calendar.getTime();
+    }
+
+    public  boolean isLeapYearExample(int year) {
+        GregorianCalendar cal = (GregorianCalendar) GregorianCalendar.getInstance();
+        return cal.isLeapYear(year);
+    }
+
+
+
+    public Date subtractDays(GregorianCalendar calendar, int daysToSubtract) {
+        GregorianCalendar cal = calendar;
+        cal.add(Calendar.DATE, -daysToSubtract);
+        return cal.getTime();
+    }
+
+    public Date addDays(GregorianCalendar calendar, int daysToAdd) {
+        GregorianCalendar cal = calendar;
+        cal.add(Calendar.DATE, daysToAdd);
+        return cal.getTime();
+    }
+
+    public XMLGregorianCalendar toXMLGregorianCalendar(GregorianCalendar calendar) throws DatatypeConfigurationException {
+        DatatypeFactory datatypeFactory = DatatypeFactory.newInstance();
+        return datatypeFactory.newXMLGregorianCalendar(calendar);
+    }
+
+    public Date toDate(XMLGregorianCalendar calendar) {
+        return calendar.toGregorianCalendar()
+            .getTime();
+    }
+
+    public int compareDates(GregorianCalendar firstDate, GregorianCalendar secondDate) {
+        return firstDate.compareTo(secondDate);
+    }
+
+    public String formatDate(GregorianCalendar calendar) {
+        return calendar.toZonedDateTime()
+            .format(DateTimeFormatter.ofPattern("d MMM uuuu"));
+    }
+
+}

core-java/src/test/java/com/baeldung/customexception/IncorrectFileExtensionExceptionUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.customexception;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.File;
+
+import org.junit.Test;
+
+public class IncorrectFileExtensionExceptionUnitTest {
+
+    @Test
+    public void testWhenCorrectFileExtensionGiven_ReceivesNoException() throws IncorrectFileNameException {
+        assertThat(FileManager.getFirstLine("correctFileNameWithProperExtension.txt")).isEqualTo("Default First Line");
+    }
+
+    @Test(expected = IncorrectFileExtensionException.class)
+    public void testWhenCorrectFileNameExceptionThrown_ReceivesNoException() throws IncorrectFileNameException {
+        StringBuffer sBuffer = new StringBuffer();
+        sBuffer.append("src");
+        sBuffer.append(File.separator);
+        sBuffer.append("test");
+        sBuffer.append(File.separator);
+        sBuffer.append("resources");
+        sBuffer.append(File.separator);
+        sBuffer.append("correctFileNameWithoutProperExtension");
+        FileManager.getFirstLine(sBuffer.toString());
+    }
+
+}

core-java/src/test/java/com/baeldung/customexception/IncorrectFileNameExceptionUnitTest.java

@@ -0,0 +1,19 @@
+package com.baeldung.customexception;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class IncorrectFileNameExceptionUnitTest {
+
+    @Test(expected = IncorrectFileNameException.class)
+    public void testWhenIncorrectFileNameExceptionThrown_ReceivesIncorrectFileNameException() throws IncorrectFileNameException {
+        FileManager.getFirstLine("wrongFileName.txt");
+    }
+
+    @Test
+    public void testWhenCorrectFileNameExceptionThrown_ReceivesNoException() throws IncorrectFileNameException {
+        assertThat(FileManager.getFirstLine("correctFileName.txt")).isEqualTo("Default First Line");
+    }
+
+}

core-java/src/test/java/com/baeldung/encrypt/FileEncrypterDecrypterIntegrationTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.encrypt;
+
+import org.junit.Test;
+
+import javax.crypto.KeyGenerator;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKey;
+import java.io.File;
+import java.io.IOException;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+
+public class FileEncrypterDecrypterIntegrationTest {
+
+    @Test
+    public void givenStringAndFilename_whenEncryptingIntoFile_andDecryptingFileAgain_thenOriginalStringIsReturned() throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IOException, InvalidAlgorithmParameterException {
+        String originalContent = "foobar";
+        SecretKey secretKey = KeyGenerator.getInstance("AES").generateKey();
+
+        FileEncrypterDecrypter fileEncrypterDecrypter = new FileEncrypterDecrypter(secretKey, "AES/CBC/PKCS5Padding");
+        fileEncrypterDecrypter.encrypt(originalContent, "baz.enc");
+
+        String decryptedContent = fileEncrypterDecrypter.decrypt("baz.enc");
+        assertThat(decryptedContent, is(originalContent));
+
+        new File("baz.enc").delete(); // cleanup
+    }
+}

core-java/src/test/java/com/baeldung/exceptions/GlobalExceptionHandlerUnitTest.java

@@ -0,0 +1,64 @@
+package com.baeldung.exceptions;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.slf4j.LoggerFactory;
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.classic.spi.LoggingEvent;
+import ch.qos.logback.core.Appender;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.verify;
+
+@RunWith(MockitoJUnitRunner.class)
+public class GlobalExceptionHandlerUnitTest {
+
+    @Mock
+    private Appender<ILoggingEvent> mockAppender;
+
+    @Captor
+    private ArgumentCaptor<LoggingEvent> captorLoggingEvent;
+
+    @Before
+    public void setup() {
+        final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
+        logger.addAppender(mockAppender);
+
+        Handler globalExceptionHandler = new Handler();
+        Thread.setDefaultUncaughtExceptionHandler(globalExceptionHandler);
+    }
+
+    @After
+    public void teardown() {
+        final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
+        logger.detachAppender(mockAppender);
+    }
+
+    @Test
+    public void whenArithmeticException_thenUseUncaughtExceptionHandler() throws InterruptedException {
+
+        Thread globalExceptionHandlerThread = new Thread() {
+            public void run() {
+                GlobalExceptionHandler globalExceptionHandlerObj = new GlobalExceptionHandler();
+                globalExceptionHandlerObj.performArithmeticOperation(99, 0);
+            }
+        };
+
+        globalExceptionHandlerThread.start();
+        globalExceptionHandlerThread.join();
+
+        verify(mockAppender).doAppend(captorLoggingEvent.capture());
+        LoggingEvent loggingEvent = captorLoggingEvent.getValue();
+
+        assertThat(loggingEvent.getLevel()).isEqualTo(Level.INFO);
+        assertThat(loggingEvent.getFormattedMessage()).isEqualTo("Unhandled exception caught!");
+    }
+
+}

core-java/src/test/java/com/baeldung/gregorian/calendar/GregorianCalendarTester.java

@@ -0,0 +1,228 @@
+package com.baeldung.gregorian.calendar;
+
+import static org.junit.Assert.*;
+
+import java.time.format.DateTimeFormatter;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
+import java.util.Locale;
+import java.util.TimeZone;
+
+import javax.xml.datatype.DatatypeConfigurationException;
+import javax.xml.datatype.DatatypeFactory;
+import javax.xml.datatype.XMLGregorianCalendar;
+
+import org.junit.Test;
+
+import com.baeldung.gregorian.calendar.GregorianCalendarExample;
+
+public class GregorianCalendarTester {
+
+    @Test
+    public void test_Calendar_Return_Type_Valid() {
+        Calendar calendar = Calendar.getInstance();
+        assert ("gregory".equals(calendar.getCalendarType()));
+    }
+
+    @Test
+    public void test_Calendar_Return_Type_InValid() {
+        Calendar calendar = Calendar.getInstance();
+        assertNotEquals("gregorys", calendar.getCalendarType());
+    }
+
+    @Test(expected = ClassCastException.class)
+    public void test_Class_Cast_Exception() {
+        TimeZone tz = TimeZone.getTimeZone("GMT+9:00");
+        Locale loc = new Locale("ja", "JP", "JP");
+        Calendar calendar = Calendar.getInstance(loc);
+        GregorianCalendar gc = (GregorianCalendar) calendar;
+    }
+
+    @Test
+    public void test_Getting_Calendar_information() {
+        GregorianCalendar calendar = new GregorianCalendar(2018, 5, 28);
+        assertTrue(false == calendar.isLeapYear(calendar.YEAR));
+        assertTrue(52 == calendar.getWeeksInWeekYear());
+        assertTrue(2018 == calendar.getWeekYear());
+        assertTrue(30 == calendar.getActualMaximum(calendar.DAY_OF_MONTH));
+        assertTrue(1 == calendar.getActualMinimum(calendar.DAY_OF_MONTH));
+        assertTrue(1 == calendar.getGreatestMinimum(calendar.DAY_OF_MONTH));
+        assertTrue(28 == calendar.getLeastMaximum(calendar.DAY_OF_MONTH));
+        assertTrue(31 == calendar.getMaximum(calendar.DAY_OF_MONTH));
+        assertTrue(1 == calendar.getMinimum(calendar.DAY_OF_MONTH));
+        assertTrue(52 == calendar.getWeeksInWeekYear());
+    }
+
+    @Test
+    public void test_Compare_Date_FirstDate_Greater_SecondDate() {
+        GregorianCalendar firstDate = new GregorianCalendar(2018, 6, 28);
+        GregorianCalendar secondDate = new GregorianCalendar(2018, 5, 28);
+        assertTrue(1 == firstDate.compareTo(secondDate));
+    }
+
+
+    @Test
+    public void test_Compare_Date_FirstDate_Smaller_SecondDate() {
+        GregorianCalendar firstDate = new GregorianCalendar(2018, 5, 28);
+        GregorianCalendar secondDate = new GregorianCalendar(2018, 6, 28);
+        assertTrue(-1 == firstDate.compareTo(secondDate));
+    }
+
+    @Test
+    public void test_Compare_Date_Both_Dates_Equal() {
+        GregorianCalendar firstDate = new GregorianCalendar(2018, 6, 28);
+        GregorianCalendar secondDate = new GregorianCalendar(2018, 6, 28);
+        assertTrue(0 == firstDate.compareTo(secondDate));
+    }
+
+    @Test
+    public void test_date_format() {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        GregorianCalendar calendar = new GregorianCalendar(2018, 6, 28);
+        assertEquals("28 Jul 2018", calendarDemo.formatDate(calendar));
+    }
+
+    @Test
+    public void test_dateFormatdMMMuuuu() {
+        String expectedDate = new GregorianCalendar(2018, 6, 28).toZonedDateTime()
+            .format(DateTimeFormatter.ofPattern("d MMM uuuu"));
+        assertEquals("28 Jul 2018", expectedDate);
+    }
+
+    @Test
+    public void test_addDays() {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        GregorianCalendar calendarActual = new GregorianCalendar(2018, 6, 28);
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        calendarExpected.add(Calendar.DATE, 1);
+        Date expectedDate = calendarExpected.getTime();
+        assertEquals(expectedDate, calendarDemo.addDays(calendarActual, 1));
+    }
+
+    @Test
+    public void test_whenAddOneDay_thenMonthIsChanged() {
+        final int finalDay1 = 1;
+        final int finalMonthJul = 6; 
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 5, 30);
+        calendarExpected.add(Calendar.DATE, 1);
+        System.out.println(calendarExpected.getTime());
+        assertEquals(calendarExpected.get(Calendar.DATE), finalDay1);
+        assertEquals(calendarExpected.get(Calendar.MONTH), finalMonthJul);
+    }
+
+    @Test
+    public void test_whenSubtractOneDay_thenMonthIsChanged() {
+        final int finalDay31 = 31;
+        final int finalMonthMay = 4; 
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 5, 1);
+        calendarExpected.add(Calendar.DATE, -1);
+        assertEquals(calendarExpected.get(Calendar.DATE), finalDay31);
+        assertEquals(calendarExpected.get(Calendar.MONTH), finalMonthMay);
+    }
+
+    @Test
+    public void test_subDays() {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        GregorianCalendar calendarActual = new GregorianCalendar(2018, 6, 28);
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        calendarExpected.add(Calendar.DATE, -1);
+        Date expectedDate = calendarExpected.getTime();
+        assertEquals(expectedDate, calendarDemo.subtractDays(calendarActual, 1));
+    }
+
+    @Test
+    public void test_rollAdd() {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        GregorianCalendar calendarActual = new GregorianCalendar(2018, 6, 28);
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        calendarExpected.roll(Calendar.MONTH, 8);
+        Date expectedDate = calendarExpected.getTime();
+        assertEquals(expectedDate, calendarDemo.rollAdd(calendarActual, 8));
+    }
+
+    @Test
+    public void test_whenRollUpOneMonth_thenYearIsUnchanged() {
+        final int rolledUpMonthJuly = 7, orginalYear2018 = 2018;
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        calendarExpected.roll(Calendar.MONTH, 1);
+        assertEquals(calendarExpected.get(Calendar.MONTH), rolledUpMonthJuly);
+        assertEquals(calendarExpected.get(Calendar.YEAR), orginalYear2018);
+    }
+
+    @Test
+    public void test_whenRollDownOneMonth_thenYearIsUnchanged() {
+        final int rolledDownMonthJune = 5, orginalYear2018 = 2018;
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        calendarExpected.roll(Calendar.MONTH, -1);
+        assertEquals(calendarExpected.get(Calendar.MONTH), rolledDownMonthJune);
+        assertEquals(calendarExpected.get(Calendar.YEAR), orginalYear2018);
+    }
+
+    @Test
+    public void test_rollSubtract() {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        GregorianCalendar calendarActual = new GregorianCalendar(2018, 6, 28);
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        calendarExpected.roll(Calendar.MONTH, -8);
+        Date expectedDate = calendarExpected.getTime();
+        assertEquals(expectedDate, calendarDemo.rollAdd(calendarActual, -8));
+    }
+
+    @Test
+    public void test_setMonth() {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        GregorianCalendar calendarActual = new GregorianCalendar(2018, 6, 28);
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        calendarExpected.set(Calendar.MONTH, 3);
+        Date expectedDate = calendarExpected.getTime();
+        assertEquals(expectedDate, calendarDemo.setMonth(calendarActual, 3));
+    }
+
+    @Test
+    public void test_setMonthApril() {
+        final int setMonthApril = 3, orginalYear2018 = 2018, originalDate28 = 28;
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        calendarExpected.set(Calendar.MONTH, 3);
+        assertEquals(calendarExpected.get(Calendar.MONTH), setMonthApril);
+        assertEquals(calendarExpected.get(Calendar.YEAR), orginalYear2018);
+        assertEquals(calendarExpected.get(Calendar.DATE), originalDate28);
+    }
+
+    @Test
+    public void test_toXMLGregorianCalendar() throws DatatypeConfigurationException {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        DatatypeFactory datatypeFactory = DatatypeFactory.newInstance();
+        GregorianCalendar calendarActual = new GregorianCalendar(2018, 6, 28);
+        GregorianCalendar calendarExpected = new GregorianCalendar(2018, 6, 28);
+        XMLGregorianCalendar expectedXMLGregorianCalendar = datatypeFactory
+            .newXMLGregorianCalendar(calendarExpected);
+        assertEquals(expectedXMLGregorianCalendar, 
+            calendarDemo.toXMLGregorianCalendar(calendarActual));
+    }
+
+    @Test
+    public void test_isLeapYear_True() {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        assertEquals(true, calendarDemo.isLeapYearExample(2016));
+
+    }
+
+    @Test
+    public void test_isLeapYear_False() {
+        GregorianCalendarExample calendarDemo = new GregorianCalendarExample();
+        assertEquals(false, calendarDemo.isLeapYearExample(2018));
+
+    }
+    
+    @Test
+    public void test_toDate() throws DatatypeConfigurationException {
+        GregorianCalendar calendarActual = new GregorianCalendar(2018, 6, 28);
+        DatatypeFactory datatypeFactory = DatatypeFactory.newInstance();
+        XMLGregorianCalendar expectedXMLGregorianCalendar = datatypeFactory
+            .newXMLGregorianCalendar(calendarActual);
+        expectedXMLGregorianCalendar.toGregorianCalendar().getTime();
+        assertEquals(calendarActual.getTime(), 
+            expectedXMLGregorianCalendar.toGregorianCalendar().getTime() );
+    }
+}

core-java/src/test/java/com/baeldung/thread/join/ThreadJoinUnitTest.java

@@ -0,0 +1,95 @@
+package com.baeldung.thread.join;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.util.logging.Logger;
+
+import org.junit.Ignore;
+import org.junit.Test;
+
+/**
+ * Demonstrates Thread.join behavior.
+ *
+ */
+public class ThreadJoinUnitTest {
+
+    final static Logger LOGGER = Logger.getLogger(ThreadJoinUnitTest.class.getName());
+
+    class SampleThread extends Thread {
+        public int processingCount = 0;
+
+        SampleThread(int processingCount) {
+            this.processingCount = processingCount;
+            LOGGER.info("Thread " + this.getName() + " created");
+        }
+
+        @Override
+        public void run() {
+            LOGGER.info("Thread " + this.getName() + " started");
+            while (processingCount > 0) {
+                try {
+                    Thread.sleep(1000); // Simulate some work being done by thread
+                } catch (InterruptedException e) {
+                    LOGGER.info("Thread " + this.getName() + " interrupted.");
+                }
+                processingCount--;
+                LOGGER.info("Inside Thread " + this.getName() + ", processingCount = " + processingCount);
+            }
+            LOGGER.info("Thread " + this.getName() + " exiting");
+        }
+    }
+
+    @Test
+    public void givenNewThread_whenJoinCalled_returnsImmediately() throws InterruptedException {
+        Thread t1 = new SampleThread(0);
+        LOGGER.info("Invoking join.");
+        t1.join();
+        LOGGER.info("Returned from join");
+        LOGGER.info("Thread state is" + t1.getState());
+        assertFalse(t1.isAlive());
+    }
+
+    @Test
+    public void givenStartedThread_whenJoinCalled_waitsTillCompletion() 
+      throws InterruptedException {
+        Thread t2 = new SampleThread(1);
+        t2.start();
+        LOGGER.info("Invoking join.");
+        t2.join();
+        LOGGER.info("Returned from join");
+        assertFalse(t2.isAlive());
+    }
+
+    @Test
+    public void givenStartedThread_whenTimedJoinCalled_waitsUntilTimedout() 
+      throws InterruptedException {
+        Thread t3 = new SampleThread(10);
+        t3.start();
+        t3.join(1000);
+        assertTrue(t3.isAlive());
+    }
+
+    @Test
+    @Ignore
+    public void givenThreadTerminated_checkForEffect_notGuaranteed() 
+      throws InterruptedException {
+        SampleThread t4 = new SampleThread(10);
+        t4.start();
+      //not guaranteed to stop even if t4 finishes.
+        do {
+            
+        } while (t4.processingCount > 0);  
+    }
+
+    @Test
+    public void givenJoinWithTerminatedThread_checkForEffect_guaranteed() 
+      throws InterruptedException {
+        SampleThread t4 = new SampleThread(10);
+        t4.start();
+        do {
+            t4.join(100);
+        } while (t4.processingCount > 0);
+    }
+
+}

core-kotlin/.gitignore

@@ -1 +1,14 @@
 /bin/
+
+#ignore gradle
+.gradle/
+
+
+#ignore build and generated files
+build/
+node/
+out/
+
+#ignore installed node modules and package lock file
+node_modules/
+package-lock.json

core-kotlin/README.md

@@ -30,3 +30,6 @@
 - [Lambda Expressions in Kotlin](http://www.baeldung.com/kotlin-lambda-expressions)
 - [Writing Specifications with Kotlin and Spek](http://www.baeldung.com/kotlin-spek)
 - [Processing JSON with Kotlin and Klaxson](http://www.baeldung.com/kotlin-json-klaxson)
+- [Kotlin String Templates](http://www.baeldung.com/kotlin-string-template)
+- [Java EE 8 Security API](http://www.baeldung.com/java-ee-8-security)
+- [Kotlin with Ktor](http://www.baeldung.com/kotlin-ktor)

core-kotlin/build.gradle

@@ -0,0 +1,57 @@
+
+
+group 'com.baeldung.ktor'
+version '1.0-SNAPSHOT'
+
+
+buildscript {
+    ext.kotlin_version = '1.2.41'
+    ext.ktor_version = '0.9.2'
+
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+apply plugin: 'java'
+apply plugin: 'kotlin'
+apply plugin: 'application'
+
+mainClassName = 'APIServer.kt'
+
+sourceCompatibility = 1.8
+compileKotlin { kotlinOptions.jvmTarget = "1.8" }
+compileTestKotlin { kotlinOptions.jvmTarget = "1.8" }
+
+kotlin { experimental { coroutines "enable" } }
+
+repositories {
+    mavenCentral()
+    jcenter()
+    maven { url "https://dl.bintray.com/kotlin/ktor" }
+}
+sourceSets {
+    main{
+        kotlin{
+            srcDirs 'com/baeldung/ktor'
+        }
+    }
+
+}
+
+dependencies {
+    compile "io.ktor:ktor-server-netty:$ktor_version"
+    compile "ch.qos.logback:logback-classic:1.2.1"
+    compile "io.ktor:ktor-gson:$ktor_version"
+    testCompile group: 'junit', name: 'junit', version: '4.12'
+    implementation 'com.beust:klaxon:3.0.1'
+
+}
+task runServer(type: JavaExec) {
+    main = 'APIServer'
+   classpath = sourceSets.main.runtimeClasspath
+}

core-kotlin/kotlin-ktor/build.gradle

@@ -5,7 +5,7 @@ version '1.0-SNAPSHOT'
 
 
 buildscript {
-    ext.kotlin_version = '1.2.40'
+    ext.kotlin_version = '1.2.41'
     ext.ktor_version = '0.9.2'
 
     repositories {

core-kotlin/kotlin-ktor/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-bin.zip

core-kotlin/kotlin-ktor/gradlew

@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"

core-kotlin/kotlin-ktor/gradlew.bat

@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

core-kotlin/kotlin-ktor/src/main/kotlin/APIServer.kt

@@ -1,26 +1,26 @@
 @file:JvmName("APIServer")
 
 
-
 import io.ktor.application.call
 import io.ktor.application.install
 import io.ktor.features.CallLogging
 import io.ktor.features.ContentNegotiation
 import io.ktor.features.DefaultHeaders
 import io.ktor.gson.gson
-import io.ktor.http.ContentType
 import io.ktor.request.path
+import io.ktor.request.receive
 import io.ktor.response.respond
-import io.ktor.response.respondText
+import io.ktor.routing.*
-import io.ktor.routing.get
-import io.ktor.routing.routing
 import io.ktor.server.engine.embeddedServer
 import io.ktor.server.netty.Netty
 import org.slf4j.event.Level
 
 data class Author(val name: String, val website: String)
+data class ToDo(var id: Int, val name: String, val description: String, val completed: Boolean)
+
 fun main(args: Array<String>) {
 
+    val toDoList = ArrayList<ToDo>();
     val jsonResponse = """{
             "id": 1,
             "task": "Pay waterbill",
@@ -33,7 +33,7 @@ fun main(args: Array<String>) {
             header("X-Developer", "Baeldung")
         }
         install(CallLogging) {
-            level = Level.INFO
+            level = Level.DEBUG
             filter { call -> call.request.path().startsWith("/todo") }
             filter { call -> call.request.path().startsWith("/author") }
         }
@@ -42,15 +42,31 @@ fun main(args: Array<String>) {
                 setPrettyPrinting()
             }
         }
-        routing {
+        routing() {
-            get("/todo") {
+            route("/todo") {
-                call.respondText(jsonResponse, ContentType.Application.Json)
+                post {
-            }
+                    var toDo = call.receive<ToDo>();
-            get("/author") {
+                    toDo.id = toDoList.size;
-                val author = Author("baeldung", "baeldung.com")
+                    toDoList.add(toDo);
-                call.respond(author)
+                    call.respond("Added")
 
+                }
+                delete("/{id}") {
+                    call.respond(toDoList.removeAt(call.parameters["id"]!!.toInt()));
+                }
+                get("/{id}") {
+
+                    call.respond(toDoList[call.parameters["id"]!!.toInt()]);
+                }
+                get {
+                    call.respond(toDoList);
+                }
             }
+        get("/author"){
+            call.respond(Author("Baeldung","baeldung.com"));
+
+        }
+
 
         }
     }.start(wait = true)

core-kotlin/resources/logback.xml

@@ -0,0 +1,11 @@
+<configuration>
+  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+    <encoder>
+      <pattern>%d{YYYY-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
+    </encoder>
+  </appender>
+
+  <root level="INFO">
+    <appender-ref ref="STDOUT"/>
+  </root>
+</configuration>

core-kotlin/settings.gradle

@@ -0,0 +1,2 @@
+rootProject.name = 'KtorWithKotlin'
+

core-kotlin/src/main/kotlin/com/baeldung/ktor/APIServer.kt

@@ -0,0 +1,73 @@
+@file:JvmName("APIServer")
+
+
+import io.ktor.application.call
+import io.ktor.application.install
+import io.ktor.features.CallLogging
+import io.ktor.features.ContentNegotiation
+import io.ktor.features.DefaultHeaders
+import io.ktor.gson.gson
+import io.ktor.request.path
+import io.ktor.request.receive
+import io.ktor.response.respond
+import io.ktor.routing.*
+import io.ktor.server.engine.embeddedServer
+import io.ktor.server.netty.Netty
+import org.slf4j.event.Level
+
+data class Author(val name: String, val website: String)
+data class ToDo(var id: Int, val name: String, val description: String, val completed: Boolean)
+
+fun main(args: Array<String>) {
+
+    val toDoList = ArrayList<ToDo>();
+    val jsonResponse = """{
+            "id": 1,
+            "task": "Pay waterbill",
+            "description": "Pay water bill today",
+        }"""
+
+
+    embeddedServer(Netty, 8080) {
+        install(DefaultHeaders) {
+            header("X-Developer", "Baeldung")
+        }
+        install(CallLogging) {
+            level = Level.DEBUG
+            filter { call -> call.request.path().startsWith("/todo") }
+            filter { call -> call.request.path().startsWith("/author") }
+        }
+        install(ContentNegotiation) {
+            gson {
+                setPrettyPrinting()
+            }
+        }
+        routing() {
+            route("/todo") {
+                post {
+                    var toDo = call.receive<ToDo>();
+                    toDo.id = toDoList.size;
+                    toDoList.add(toDo);
+                    call.respond("Added")
+
+                }
+                delete("/{id}") {
+                    call.respond(toDoList.removeAt(call.parameters["id"]!!.toInt()));
+                }
+                get("/{id}") {
+
+                    call.respond(toDoList[call.parameters["id"]!!.toInt()]);
+                }
+                get {
+                    call.respond(toDoList);
+                }
+            }
+        get("/author"){
+            call.respond(Author("Baeldung","baeldung.com"));
+
+        }
+
+
+        }
+    }.start(wait = true)
+}

data-structures/src/main/java/com/baeldung/trie/Trie.java

@@ -1,13 +1,13 @@
 package com.baeldung.trie;
 
-public class Trie {
+class Trie {
     private TrieNode root;
 
     Trie() {
         root = new TrieNode();
     }
 
-    public void insert(String word) {
+    void insert(String word) {
         TrieNode current = root;
 
         for (int i = 0; i < word.length(); i++) {
@@ -16,11 +16,11 @@ public class Trie {
         current.setEndOfWord(true);
     }
 
-    public boolean delete(String word) {
+    boolean delete(String word) {
         return delete(root, word, 0);
     }
 
-    public boolean containsNode(String word) {
+    boolean containsNode(String word) {
         TrieNode current = root;
 
         for (int i = 0; i < word.length(); i++) {
@@ -34,7 +34,7 @@ public class Trie {
         return current.isEndOfWord();
     }
 
-    public boolean isEmpty() {
+    boolean isEmpty() {
         return root == null;
     }
 
@@ -51,7 +51,7 @@ public class Trie {
         if (node == null) {
             return false;
         }
-        boolean shouldDeleteCurrentNode = delete(node, word, index + 1);
+        boolean shouldDeleteCurrentNode = delete(node, word, index + 1) && !node.isEndOfWord();
 
         if (shouldDeleteCurrentNode) {
             current.getChildren().remove(ch);

data-structures/src/main/java/com/baeldung/trie/TrieNode.java

@@ -4,28 +4,18 @@ import java.util.HashMap;
 import java.util.Map;
 
 class TrieNode {
-    private Map<Character, TrieNode> children;
+    private final Map<Character, TrieNode> children = new HashMap<>();
     private boolean endOfWord;
 
-    public TrieNode() {
+    Map<Character, TrieNode> getChildren() {
-        children = new HashMap<>();
-        endOfWord = false;
-    }
-
-    public Map<Character, TrieNode> getChildren() {
         return children;
     }
 
-    public void setChildren(Map<Character, TrieNode> children) {
+    boolean isEndOfWord() {
-        this.children = children;
-    }
-
-    public boolean isEndOfWord() {
         return endOfWord;
     }
 
-    public void setEndOfWord(boolean endOfWord) {
+    void setEndOfWord(boolean endOfWord) {
         this.endOfWord = endOfWord;
     }
-
 }

data-structures/src/test/java/com/baeldung/trie/TrieTest.java

@@ -1,6 +1,7 @@
 package com.baeldung.trie;
 
 import org.junit.Test;
+import org.junit.jupiter.api.Assertions;
 
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
@@ -53,6 +54,19 @@ public class TrieTest {
         assertFalse(trie.containsNode("Programming"));
     }
 
+    @Test
+    public void givenATrie_whenDeletingOverlappingElements_thenDontDeleteSubElement() {
+
+        Trie trie1 = new Trie();
+
+        trie1.insert("pie");
+        trie1.insert("pies");
+
+        trie1.delete("pies");
+
+        Assertions.assertTrue(trie1.containsNode("pie"));
+    }
+
     private Trie createExampleTrie() {
         Trie trie = new Trie();
 

deltaspike/README.md

@@ -1 +1,3 @@
 ## Relevant articles:
+
+- [A Guide to DeltaSpike Data Module](http://www.baeldung.com/deltaspike-data-module)

ejb/wildfly/wildfly-mdb/pom.xml

@@ -0,0 +1,21 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>widlfly-mdb</artifactId>
+
+    <parent>
+        <groupId>com.baeldung.wildfly</groupId>
+        <artifactId>wildfly-example</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <!-- Dependency for java ee -->
+        <dependency>
+            <groupId>javax</groupId>
+            <artifactId>javaee-api</artifactId>
+            <version>${javaee-api.version}</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+</project>

ejb/wildfly/wildfly-mdb/src/com/baeldung/wildfly/mdb/ReadMessageMDB.java

@@ -0,0 +1,28 @@
+package com.baeldung.wildfly.mdb;
+
+import javax.ejb.ActivationConfigProperty;
+import javax.ejb.MessageDriven;
+import javax.jms.JMSException;
+import javax.jms.Message;
+import javax.jms.MessageListener;
+import javax.jms.TextMessage;
+
+/**
+ * Message-Driven Bean implementation class for: ReadMessageMDB
+ */
+@MessageDriven(
+        activationConfig = { 
+            @ActivationConfigProperty(propertyName = "destination", propertyValue = "tutorialQueue"), 
+            @ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue")
+})
+public class ReadMessageMDB implements MessageListener {
+
+    public void onMessage(Message message) {
+        TextMessage textMessage = (TextMessage) message;
+        try {
+            System.out.println("Message received: " + textMessage.getText());
+        } catch (JMSException e) {
+            System.out.println("Error while trying to consume messages: " + e.getMessage());
+        }
+    }
+}

ejb/wildfly/wildfly-mdb/src/com/baeldung/wildfly/mdb/SendMessageServlet.java

@@ -0,0 +1,52 @@
+package baeldung.com.example.servlet;
+
+import java.io.IOException;
+
+import javax.jms.Connection;
+import javax.jms.ConnectionFactory;
+import javax.jms.JMSException;
+import javax.jms.MessageProducer;
+import javax.jms.Queue;
+import javax.jms.Session;
+import javax.jms.TextMessage;
+import javax.naming.Context;
+import javax.naming.InitialContext;
+import javax.naming.NamingException;
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+
+@WebServlet("/SendMessageServlet")
+public class SendMessageServlet extends HttpServlet {
+ 
+    @Override
+    protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
+        String text = req.getParameter("text") != null ? req.getParameter("text") : "Hello World";
+
+        try (
+            Context ic = new InitialContext();
+ 
+            ConnectionFactory cf = (ConnectionFactory) ic.lookup("/ConnectionFactory");
+            Queue queue = (Queue) ic.lookup("queue/tutorialQueue");
+ 
+            Connection connection = cf.createConnection();
+        ) {
+            Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
+            MessageProducer publisher = session.createProducer(queue);
+ 
+            connection.start();
+
+            TextMessage message = session.createTextMessage(text);
+            publisher.send(message);
+ 
+        } catch (NamingException | JMSException e) {
+            res.getWriter().println("Error while trying to send <" + text + "> message: " + e.getMessage());
+        } 
+
+        res.getWriter().println("Message sent: " + text);
+    }
+ 
+}

ethereum/README.md

@@ -1,4 +1,4 @@
-## EthereumJ
+## Ethereum
 
 ### Relevant Articles:
 - [Introduction to EthereumJ](http://www.baeldung.com/ethereumj)

ethereum/pom.xml

@@ -0,0 +1,229 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.ethereum</groupId>
+    <artifactId>ethereum</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>ethereum</name>
+
+    <parent>
+        <artifactId>parent-spring-5</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-spring-5</relativePath>
+    </parent>
+
+    <dependencies>
+
+        <!-- Spring Boot Dependencies -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+            <version>${spring.boot.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+            <version>${spring.boot.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-tomcat</artifactId>
+            <version>${spring.boot.version}</version>
+        </dependency>
+
+        <!-- Spring Dependencies -->
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-core</artifactId>
+            <version>${springframework.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-web</artifactId>
+            <version>${springframework.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-webmvc</artifactId>
+            <version>${springframework.version}</version>
+        </dependency>
+
+        <!-- Ethereum -->
+        <dependency>
+            <groupId>org.ethereum</groupId>
+            <artifactId>ethereumj-core</artifactId>
+            <version>${ethereumj-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.web3j</groupId>
+            <artifactId>core</artifactId>
+            <version>${web3j.core.version}</version>
+        </dependency>
+
+        <!-- Jackson Dependencies -->
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-annotations</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+
+        <!-- Servlet -->
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>jstl</artifactId>
+            <version>${jstl.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>javax.servlet-api</artifactId>
+            <version>${javax-servlet.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet.jsp.jstl</groupId>
+            <artifactId>jstl-api</artifactId>
+            <version>${jstl.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet.jsp</groupId>
+            <artifactId>javax.servlet.jsp-api</artifactId>
+            <version>${javax-jsp.version}</version>
+        </dependency>
+
+        <!-- Logging -->
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>jcl-over-slf4j</artifactId>
+            <version>${slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>${logback.version}</version>
+        </dependency>
+
+        <!-- Spring Testing -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+            <version>${spring.boot.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-context</artifactId>
+            <version>${springframework.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-test</artifactId>
+            <version>${springframework.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- Testing -->
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${mockito.version}</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.hamcrest</groupId>
+                    <artifactId>hamcrest-core</artifactId>
+                </exclusion>
+            </exclusions>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.hamcrest</groupId>
+                    <artifactId>hamcrest-core</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-library</artifactId>
+            <version>${hamcrest.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.jayway.jsonpath</groupId>
+            <artifactId>json-path</artifactId>
+            <version>${jsonpath.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>ethereum</finalName>
+        <plugins>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.1</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-war-plugin</artifactId>
+                <version>3.0.0</version>
+                <configuration>
+                    <warSourceDirectory>src/main/webapp</warSourceDirectory>
+                    <failOnMissingWebXml>false</failOnMissingWebXml>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <repositories>
+        <repository>
+            <id>Ethereum</id>
+            <name>Ethereum</name>
+            <url>https://dl.bintray.com/ethereum/maven/</url>
+        </repository>
+    </repositories>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <java.version>1.8</java.version>
+        <tomcat.version>8.5.4</tomcat.version>
+        <ethereumj-core.version>1.5.0-RELEASE</ethereumj-core.version>
+        <web3j.core.version>3.3.1</web3j.core.version>
+        <springframework.version>5.0.5.RELEASE</springframework.version>
+        <spring.boot.version>1.5.6.RELEASE</spring.boot.version>
+        <mockito.version>1.10.19</mockito.version>
+        <jackson-databind.version>2.5.0</jackson-databind.version>
+        <hamcrest.version>1.3</hamcrest.version>
+        <jackson.version>2.9.3</jackson.version>
+        <javax-jsp.version>2.3.1</javax-jsp.version>
+        <javax-servlet.version>3.1.0</javax-servlet.version>
+        <jsonpath.version>2.4.0</jsonpath.version>
+        <jstl.version>1.2</jstl.version>
+        <junit.version>4.12</junit.version>
+        <logback.version>1.2.3</logback.version>
+        <slf4j.version>1.7.25</slf4j.version>
+    </properties>
+
+</project>

ethereum/src/main/java/com/baeldung/web3j/config/AppConfig.java

@@ -0,0 +1,68 @@
+package com.baeldung.web3j.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.scheduling.annotation.EnableAsync;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
+import org.springframework.web.servlet.config.annotation.EnableWebMvc;
+import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
+import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+import org.springframework.web.servlet.resource.PathResourceResolver;
+import org.springframework.web.servlet.view.JstlView;
+import org.springframework.web.servlet.view.UrlBasedViewResolver;
+
+import java.util.concurrent.Executor;
+
+@Configuration
+@EnableWebMvc
+@EnableAsync
+@ComponentScan("com.baeldung.web3j")
+public class AppConfig implements WebMvcConfigurer {
+
+    public void addViewControllers(ViewControllerRegistry registry) {
+        registry.addViewController("/").setViewName("index");
+    }
+
+    /**
+     * Static resource locations including themes
+     */
+    @Override
+    public void addResourceHandlers(ResourceHandlerRegistry registry) {
+        registry.addResourceHandler("/resources/**/*")
+                .addResourceLocations("/", "/resources/")
+                .setCachePeriod(3600)
+                .resourceChain(true)
+                .addResolver(new PathResourceResolver());
+    }
+
+    /**
+     * View resolver for JSP
+     */
+    @Bean
+    public UrlBasedViewResolver viewResolver() {
+        UrlBasedViewResolver resolver = new UrlBasedViewResolver();
+        resolver.setPrefix("/WEB-INF/jsp/");
+        resolver.setSuffix(".jsp");
+        resolver.setViewClass(JstlView.class);
+        return resolver;
+    }
+
+    /**
+     * Configuration for async thread bean
+     *
+     * More: https://docs.spring.io/autorepo/docs/spring-framework/5.0.3.RELEASE/javadoc-api/org/springframework/scheduling/SchedulingTaskExecutor.html
+     */
+    @Bean
+    public Executor asyncExecutor() {
+        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
+        executor.setCorePoolSize(2);
+        executor.setMaxPoolSize(2);
+        executor.setQueueCapacity(500);
+        executor.setThreadNamePrefix("CsvThread");
+        executor.initialize();
+        return executor;
+    }
+
+}

ethereum/src/main/java/com/baeldung/web3j/config/WebAppInitializer.java

@@ -0,0 +1,28 @@
+package com.baeldung.web3j.config;
+
+import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
+
+public class WebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
+
+    //AbstractDispatcherServletInitializer override DEFAULT_SERVLET_NAME
+    @Override
+    protected String getServletName() {
+        return "dispatcher";
+    }
+
+    @Override
+    protected Class<?>[] getRootConfigClasses() {
+        return new Class[]{};
+    }
+
+    @Override
+    protected Class<?>[] getServletConfigClasses() {
+        return new Class[]{AppConfig.class};
+    }
+
+    @Override
+    protected String[] getServletMappings() {
+        return new String[]{"/"};
+    }
+
+}