Merge branch 'eugenp:master' into master

apache-olingo/.gitignore

@@ -27,3 +27,4 @@ HELP.md
 
 ### VS Code ###
 .vscode/
+

apache-olingo/Samples.md

@@ -4,15 +4,15 @@ This following table contains test URLs that can be used with the Olingo V2 demo
 
 | URL                                      | Description                                     |
 |------------------------------------------|-------------------------------------------------|
-| `http://localhost:8180/odata/$metadata`  | fetch OData metadata document |
-| `http://localhost:8180/odata/CarMakers?$top=10&$skip=10` | Get 10 entities starting at offset 10 |
-| `http://localhost:8180/odata/CarMakers?$count` | Return total count of entities in this set |
-| `http://localhost:8180/odata/CarMakers?$filter=startswith(Name,'B')` | Return entities where the *Name* property starts with 'B' |
-| `http://localhost:8180/odata/CarModels?$filter=Year eq 2008 and CarMakerDetails/Name eq 'BWM'` | Return *CarModel* entities where the *Name* property of its maker  starts with 'B' |
-| `http://localhost:8180/odata/CarModels(1L)?$expand=CarMakerDetails` | Return the *CarModel* with primary key '1', along with its maker|
-| `http://localhost:8180/odata/CarModels(1L)?$select=Name,Sku` | Return the *CarModel* with primary key '1', returing only its *Name* and *Sku* properties |
-| `http://localhost:8180/odata/CarModels?$orderBy=Name asc,Sku desc` | Return *CarModel* entities, ordered by the their *Name* and *Sku* properties |
-| `http://localhost:8180/odata/CarModels?$format=json` | Return *CarModel* entities, using a JSON representation|
+| `http://localhost:8080/odata/$metadata`  | fetch OData metadata document |
+| `http://localhost:8080/odata/CarMakers?$top=10&$skip=10` | Get 10 entities starting at offset 10 |
+| `http://localhost:8080/odata/CarMakers?$count` | Return total count of entities in this set |
+| `http://localhost:8080/odata/CarMakers?$filter=startswith(Name,'B')` | Return entities where the *Name* property starts with 'B' |
+| `http://localhost:8080/odata/CarModels?$filter=Year eq 2008 and CarMakerDetails/Name eq 'BWM'` | Return *CarModel* entities where the *Name* property of its maker  starts with 'B' |
+| `http://localhost:8080/odata/CarModels(1L)?$expand=CarMakerDetails` | Return the *CarModel* with primary key '1', along with its maker|
+| `http://localhost:8080/odata/CarModels(1L)?$select=Name,Sku` | Return the *CarModel* with primary key '1', returing only its *Name* and *Sku* properties |
+| `http://localhost:8080/odata/CarModels?$orderBy=Name asc,Sku desc` | Return *CarModel* entities, ordered by the their *Name* and *Sku* properties |
+| `http://localhost:8080/odata/CarModels?$format=json` | Return *CarModel* entities, using a JSON representation|
 
 
 

apache-olingo/pom.xml

@@ -3,16 +3,16 @@
     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.examples.olingo2</groupId>
-    <artifactId>olingo2</artifactId>
-    <name>olingo2</name>
-    <description>Sample Olingo 2 Project</description>
+    <groupId>com.baeldung.examples.olingo</groupId>
+    <artifactId>apache-olingo</artifactId>
+    <name>apache-olingo</name>
+    <description>Sample Apache Olingo Project</description>
 
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>parent-boot-2</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../../parent-boot-2</relativePath>
+        <relativePath>../parent-boot-2</relativePath>
     </parent>
 
     <dependencies>
@@ -43,7 +43,7 @@
         <dependency>
             <groupId>org.apache.olingo</groupId>
             <artifactId>olingo-odata2-core</artifactId>
-            <version>${olingo2.version}</version>
+            <version>${olingo.version}</version>
             <!-- Avoid jax-rs version conflict by excluding Olingo's version -->
             <exclusions>
                 <exclusion>
@@ -55,12 +55,12 @@
         <dependency>
             <groupId>org.apache.olingo</groupId>
             <artifactId>olingo-odata2-jpa-processor-core</artifactId>
-            <version>${olingo2.version}</version>
+            <version>${olingo.version}</version>
         </dependency>
         <dependency>
             <groupId>org.apache.olingo</groupId>
             <artifactId>olingo-odata2-jpa-processor-ref</artifactId>
-            <version>${olingo2.version}</version>
+            <version>${olingo.version}</version>
             <exclusions>
                 <exclusion>
                     <groupId>org.eclipse.persistence</groupId>
@@ -80,7 +80,7 @@
     </build>
 
     <properties>
-        <olingo2.version>2.0.11</olingo2.version>
+        <olingo.version>2.0.11</olingo.version>
     </properties>
 
 </project>

apache-olingo/src/main/java/com/baeldung/examples/olingo2/CarsODataJPAServiceFactory.java

@@ -27,11 +27,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.stereotype.Component;
 
-/**
- * ODataJPAServiceFactory implementation for our sample domain 
- * @author Philippe
- *
- */
 @Component
 public class CarsODataJPAServiceFactory extends ODataJPAServiceFactory {
 

apache-olingo/src/main/java/com/baeldung/examples/olingo2/JerseyConfig.java

@@ -1,6 +1,12 @@
-    package com.baeldung.examples.olingo2;
+package com.baeldung.examples.olingo2;
 
-import java.io.IOException;
+import org.apache.olingo.odata2.api.ODataServiceFactory;
+import org.apache.olingo.odata2.core.rest.ODataRootLocator;
+import org.apache.olingo.odata2.core.rest.app.ODataApplication;
+import org.glassfish.jersey.server.ResourceConfig;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
 
 import javax.persistence.EntityManager;
 import javax.persistence.EntityManagerFactory;
@@ -15,19 +21,6 @@ import javax.ws.rs.container.ContainerResponseFilter;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.ext.Provider;
 
-import org.apache.olingo.odata2.api.ODataServiceFactory;
-import org.apache.olingo.odata2.core.rest.ODataRootLocator;
-import org.apache.olingo.odata2.core.rest.app.ODataApplication;
-import org.glassfish.jersey.server.ResourceConfig;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.stereotype.Component;
-
-/**
- * Jersey JAX-RS configuration
- * @author Philippe
- *
- */
 @Component
 @ApplicationPath("/odata")
 public class JerseyConfig extends ResourceConfig {
@@ -72,7 +65,7 @@ public class JerseyConfig extends ResourceConfig {
         }
 
         @Override
-        public void filter(ContainerRequestContext ctx) throws IOException {
+        public void filter(ContainerRequestContext ctx) {
             log.info("[I60] >>> filter");
             EntityManager em = this.emf.createEntityManager();
             httpRequest.setAttribute(EM_REQUEST_ATTRIBUTE, em);
@@ -85,7 +78,7 @@ public class JerseyConfig extends ResourceConfig {
         }
 
         @Override
-        public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) throws IOException {
+        public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) {
 
             log.info("[I68] <<< filter");
             EntityManager em = (EntityManager) httpRequest.getAttribute(EM_REQUEST_ATTRIBUTE);

apache-olingo/src/test/java/com/baeldung/examples/olingo2/Olingo2SampleApplicationIntegrationTest.java

@@ -7,7 +7,7 @@ import org.springframework.test.context.junit4.SpringRunner;
 
 @RunWith(SpringRunner.class)
 @SpringBootTest
-public class Olingo2SampleApplicationUnitTest {
+public class Olingo2SampleApplicationIntegrationTest {
 
 	@Test
 	public void contextLoads() {

apache-poi/.gitignore

@@ -1,3 +1,5 @@
 *.docx
 temp.xls
 temp.xlsx
+
+CellStyleTest_output.xlsx

apache-poi/README.md

@@ -14,4 +14,5 @@ This module contains articles about Apache POI.
 - [Set Background Color of a Cell with Apache POI](https://www.baeldung.com/apache-poi-background-color)
 - [Add Borders to Excel Cells With Apache POI](https://www.baeldung.com/apache-poi-add-borders)
 - [Reading Values From Excel in Java](https://www.baeldung.com/java-read-dates-excel)
+- [Change Cell Font Style with Apache POI](https://www.baeldung.com/apache-poi-change-cell-font)
 - More articles: [[next -->]](../apache-poi-2)

apache-poi/pom.xml

@@ -33,7 +33,7 @@
     </dependencies>
 
     <properties>
-        <poi.version>4.1.1</poi.version>
+        <poi.version>5.2.0</poi.version>
         <jexcel.version>1.0.6</jexcel.version>
     </properties>
 

apache-poi/src/main/java/com/baeldung/poi/excel/ExcelPOIHelper.java

@@ -1,25 +1,24 @@
 package com.baeldung.poi.excel;
 
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
 import org.apache.poi.ss.usermodel.Cell;
-import org.apache.poi.ss.usermodel.CellType;
 import org.apache.poi.ss.usermodel.CellStyle;
+import org.apache.poi.ss.usermodel.DateUtil;
+import org.apache.poi.ss.usermodel.FillPatternType;
 import org.apache.poi.ss.usermodel.IndexedColors;
 import org.apache.poi.ss.usermodel.Row;
 import org.apache.poi.ss.usermodel.Sheet;
 import org.apache.poi.ss.usermodel.Workbook;
-import org.apache.poi.xssf.usermodel.XSSFWorkbook;
 import org.apache.poi.xssf.usermodel.XSSFFont;
-import org.apache.poi.ss.usermodel.DateUtil;
-import org.apache.poi.ss.usermodel.FillPatternType;
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.Map;
-import java.util.HashMap;
-import java.util.ArrayList;
-import java.util.List;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
 
 public class ExcelPOIHelper {
 
@@ -33,7 +32,7 @@ public class ExcelPOIHelper {
         for (Row row : sheet) {
             data.put(i, new ArrayList<String>());
             for (Cell cell : row) {
-                switch (cell.getCellTypeEnum()) {
+                switch (cell.getCellType()) {
                 case STRING:
                     data.get(i)
                         .add(cell.getRichStringCellValue()

apache-poi/src/main/java/com/baeldung/poi/excel/ExcelUtility.java

@@ -44,6 +44,7 @@ public class ExcelUtility {
                 }
             }
             inputStream.close();
+            baeuldungWorkBook.close();
 
         } catch (IOException e) {
             throw e;

apache-poi/src/main/java/com/baeldung/poi/excel/cellstyle/CellStyler.java

@@ -0,0 +1,25 @@
+package com.baeldung.poi.excel.cellstyle;
+
+import org.apache.poi.hssf.util.HSSFColor.HSSFColorPredefined;
+import org.apache.poi.ss.usermodel.CellStyle;
+import org.apache.poi.ss.usermodel.Font;
+import org.apache.poi.ss.usermodel.HorizontalAlignment;
+import org.apache.poi.ss.usermodel.VerticalAlignment;
+import org.apache.poi.ss.usermodel.Workbook;
+
+public class CellStyler {
+    public CellStyle createWarningColor(Workbook workbook) {
+        CellStyle style = workbook.createCellStyle();
+
+        Font font = workbook.createFont();
+        font.setFontName("Courier New");
+        font.setBold(true);
+        font.setUnderline(Font.U_SINGLE);
+        font.setColor(HSSFColorPredefined.DARK_RED.getIndex());
+        style.setFont(font);
+
+        style.setAlignment(HorizontalAlignment.CENTER);
+        style.setVerticalAlignment(VerticalAlignment.CENTER);
+        return style;
+    }
+}

apache-poi/src/test/java/com/baeldung/jexcel/JExcelIntegrationTest.java

@@ -1,25 +1,18 @@
 package com.baeldung.jexcel;
 
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import jxl.read.biff.BiffException;
-import java.util.Map;
-import java.util.ArrayList;
-import java.util.List;
-
-import com.baeldung.jexcel.JExcelHelper;
-
-import jxl.write.WriteException;
-import jxl.read.biff.BiffException;
-
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
 
-import org.junit.Test;
-import org.junit.Before;
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
 import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import jxl.read.biff.BiffException;
+import jxl.write.WriteException;
 
 public class JExcelIntegrationTest {
 

apache-poi/src/test/java/com/baeldung/poi/excel/ExcelIntegrationTest.java

@@ -1,22 +1,15 @@
 package com.baeldung.poi.excel;
 
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import jxl.read.biff.BiffException;
-import java.util.Map;
-import java.util.ArrayList;
-import java.util.List;
-
-import com.baeldung.poi.excel.ExcelPOIHelper;
-
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
 
-import org.junit.Test;
-import org.junit.Before;
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
 import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
 
 public class ExcelIntegrationTest {
 

apache-poi/src/test/java/com/baeldung/poi/excel/cellstyle/CellStyleHandlerUnitTest.java

@@ -1,17 +1,19 @@
 package com.baeldung.poi.excel.cellstyle;
 
-import org.apache.poi.ss.usermodel.*;
-import org.apache.poi.xssf.usermodel.XSSFWorkbook;
-import org.junit.Before;
-import org.junit.Test;
+import static org.junit.Assert.assertEquals;
 
-import java.io.FileOutputStream;
 import java.io.IOException;
-import java.io.OutputStream;
 import java.net.URISyntaxException;
 import java.nio.file.Paths;
 
-import static org.junit.Assert.assertEquals;
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.IndexedColors;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.Before;
+import org.junit.Test;
 
 public class CellStyleHandlerUnitTest {
     private static final String FILE_NAME = "cellstyle/CellStyleHandlerTest.xlsx";

apache-poi/src/test/java/com/baeldung/poi/excel/cellstyle/CellStylerUnitTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.poi.excel.cellstyle;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.CellStyle;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.Before;
+import org.junit.Test;
+
+public class CellStylerUnitTest {
+    private static String FILE_NAME = "com/baeldung/poi/excel/cellstyle/CellStyle.xlsx";
+    private static final String NEW_FILE_NAME = "CellStyleTest_output.xlsx";
+    private String fileLocation;
+
+    @Before
+    public void setup() throws IOException, URISyntaxException {
+        fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME)
+            .toURI())
+            .toString();
+    }
+
+    @Test
+    public void testApplyWarningColor() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+        Row row1 = sheet.createRow(0);
+        row1.setHeightInPoints((short) 40);
+
+        CellStyler styler = new CellStyler();
+        CellStyle style = styler.createWarningColor(workbook);
+
+        Cell cell1 = row1.createCell(0);
+        cell1.setCellStyle(style);
+        cell1.setCellValue("Hello");
+
+        Cell cell2 = row1.createCell(1);
+        cell2.setCellStyle(style);
+        cell2.setCellValue("world!");
+
+        FileOutputStream outputStream = new FileOutputStream(NEW_FILE_NAME);
+        workbook.write(outputStream);
+        outputStream.close();
+        workbook.close();
+    }
+}

apache-spark/src/test/java/com/baeldung/differences/rdd/TransformationsUnitTest.java

@@ -1,9 +1,9 @@
 package com.baeldung.differences.rdd;
 
-
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
+import org.apache.commons.io.FileUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.spark.SparkConf;
 import org.apache.spark.api.java.JavaRDD;
@@ -12,9 +12,12 @@ import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
+import java.io.File;
+
 public class TransformationsUnitTest {
 
     public static final String COMMA_DELIMITER = ",(?=([^\"]*\"[^\"]*\")*[^\"]*$)";
+
     private static JavaSparkContext sc;
     private static JavaRDD<String> tourists;
 
@@ -25,6 +28,9 @@ public class TransformationsUnitTest {
         sc = new JavaSparkContext(conf);
         tourists = sc.textFile("data/Tourist.csv")
             .filter(line -> !line.startsWith("Region")); //filter header row
+
+        // delete previous output dir and files
+        FileUtils.deleteQuietly(new File("data/output"));
     }
 
     @AfterClass

core-java-modules/core-java-15/README.md

@@ -4,4 +4,5 @@ This module contains articles about Java 15.
 
 ### Relevant articles
 
+- [Hidden Classes in Java 15](https://www.baeldung.com/java-hidden-classes)
 - [Sealed Classes and Interfaces in Java 15](https://www.baeldung.com/java-sealed-classes-interfaces)

core-java-modules/core-java-17/README.md

@@ -1,5 +1,6 @@
 ### Relevant articles:
 
+- [An Introduction to InstantSource in Java 17](https://www.baeldung.com/java-instantsource)
 - [Pattern Matching for Switch](https://www.baeldung.com/java-switch-pattern-matching)
 - [Introduction to HexFormat in Java 17](https://www.baeldung.com/java-hexformat)
 - [New Features in Java 17](https://www.baeldung.com/java-17-new-features)

core-java-modules/core-java-collections-3/src/main/java/com/baeldung/collections/iterators/Iterators.java

@@ -1,17 +1,16 @@
 package com.baeldung.collections.iterators;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.concurrent.ConcurrentHashMap;
 
-/**
- * Source code https://github.com/eugenp/tutorials
- *
- * @author Santosh Thakur
- */
-
 public class Iterators {
 
+    private static final Logger LOG = LoggerFactory.getLogger(Iterators.class);
+
     public static int failFast1() {
         ArrayList<Integer> numbers = new ArrayList<>();
 
@@ -44,7 +43,7 @@ public class Iterators {
             }
         }
 
-        System.out.println("using iterator's remove method = " + numbers);
+        LOG.debug("using iterator's remove method = {}", numbers);
 
         iterator = numbers.iterator();
         while (iterator.hasNext()) {

core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/bitset/BitSetUnitTest.java

@@ -3,6 +3,8 @@ package com.baeldung.collections.bitset;
 import org.junit.Test;
 import org.openjdk.jol.info.ClassLayout;
 import org.openjdk.jol.info.GraphLayout;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.BitSet;
 
@@ -10,18 +12,20 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 public class BitSetUnitTest {
 
+    private static final Logger LOG = LoggerFactory.getLogger(BitSetUnitTest.class);
+
     @Test
     public void givenBoolArray_whenMemoryLayout_thenConsumeMoreThanOneBit() {
         boolean[] bits = new boolean[1024 * 1024];
 
-        System.out.println(ClassLayout.parseInstance(bits).toPrintable());
+        LOG.debug(ClassLayout.parseInstance(bits).toPrintable());
     }
 
     @Test
     public void givenBitSet_whenMemoryLayout_thenConsumeOneBitPerFlag() {
         BitSet bitSet = new BitSet(1024 * 1024);
 
-        System.out.println(GraphLayout.parseInstance(bitSet).toPrintable());
+        LOG.debug(GraphLayout.parseInstance(bitSet).toPrintable());
     }
 
     @Test
@@ -157,7 +161,7 @@ public class BitSetUnitTest {
         BitSet bitSet = new BitSet();
         bitSet.set(15, 25);
 
-        bitSet.stream().forEach(System.out::println);
+        bitSet.stream().forEach(bit -> LOG.debug(String.valueOf(bit)));
         assertThat(bitSet.stream().count()).isEqualTo(10);
     }
 

core-java-modules/core-java-collections-3/src/test/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

core-java-modules/core-java-concurrency-advanced-2/src/main/java/com/baeldung/concurrent/prioritytaskexecution/Job.java

@@ -1,8 +1,14 @@
 package com.baeldung.concurrent.prioritytaskexecution;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 public class Job implements Runnable {
-    private String jobName;
-    private JobPriority jobPriority;
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(Job.class);
+
+    private final String jobName;
+    private final JobPriority jobPriority;
 
     public Job(String jobName, JobPriority jobPriority) {
         this.jobName = jobName;
@@ -16,8 +22,7 @@ public class Job implements Runnable {
     @Override
     public void run() {
         try {
-            System.out.println("Job:" + jobName + 
-              " Priority:" + jobPriority);
+            LOGGER.debug("Job:{} Priority:{}", jobName, jobPriority);
             Thread.sleep(1000);
         } catch (InterruptedException ignored) {
         }

core-java-modules/core-java-concurrency-advanced-2/src/main/java/com/baeldung/forkjoin/CustomRecursiveAction.java

@@ -1,19 +1,21 @@
 package com.baeldung.forkjoin;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.concurrent.ForkJoinTask;
 import java.util.concurrent.RecursiveAction;
-import java.util.logging.Logger;
 
 public class CustomRecursiveAction extends RecursiveAction {
 
+    final Logger logger = LoggerFactory.getLogger(CustomRecursiveAction.class);
+
     private String workLoad = "";
     private static final int THRESHOLD = 4;
 
-    private static Logger logger = Logger.getAnonymousLogger();
-
     public CustomRecursiveAction(String workLoad) {
         this.workLoad = workLoad;
     }
@@ -43,7 +45,7 @@ public class CustomRecursiveAction extends RecursiveAction {
 
     private void processing(String work) {
         String result = work.toUpperCase();
-        logger.info("This result - (" + result + ") - was processed by " + Thread.currentThread()
+        logger.debug("This result - (" + result + ") - was processed by " + Thread.currentThread()
             .getName());
     }
 }

core-java-modules/core-java-concurrency-advanced-2/src/test/java/com/baeldung/concurrent/prioritytaskexecution/PriorityJobSchedulerUnitTest.java

@@ -3,8 +3,8 @@ package com.baeldung.concurrent.prioritytaskexecution;
 import org.junit.Test;
 
 public class PriorityJobSchedulerUnitTest {
-    private static int POOL_SIZE = 1;
-    private static int QUEUE_SIZE = 10;
+    private static final int POOL_SIZE = 1;
+    private static final int QUEUE_SIZE = 10;
 
     @Test
     public void whenMultiplePriorityJobsQueued_thenHighestPriorityJobIsPicked() {

core-java-modules/core-java-concurrency-advanced-2/src/test/java/com/baeldung/forkjoin/Java8ForkJoinIntegrationTest.java

@@ -1,18 +1,15 @@
 package com.baeldung.forkjoin;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
+import com.baeldung.forkjoin.util.PoolUtil;
+import org.junit.Before;
+import org.junit.Test;
 
 import java.util.Random;
 import java.util.concurrent.ForkJoinPool;
 
-import org.junit.Before;
-import org.junit.Test;
-
-import com.baeldung.forkjoin.CustomRecursiveAction;
-import com.baeldung.forkjoin.CustomRecursiveTask;
-import com.baeldung.forkjoin.util.PoolUtil;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 
 public class Java8ForkJoinIntegrationTest {
 
@@ -63,11 +60,11 @@ public class Java8ForkJoinIntegrationTest {
         ForkJoinPool forkJoinPool = ForkJoinPool.commonPool();
 
         forkJoinPool.execute(customRecursiveTask);
-        int result = customRecursiveTask.join();
+        customRecursiveTask.join();
         assertTrue(customRecursiveTask.isDone());
 
         forkJoinPool.submit(customRecursiveTask);
-        int resultTwo = customRecursiveTask.join();
+        customRecursiveTask.join();
         assertTrue(customRecursiveTask.isDone());
     }
 

core-java-modules/core-java-concurrency-advanced-2/src/test/java/com/baeldung/thread/join/ThreadJoinUnitTest.java

@@ -1,12 +1,12 @@
 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;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 /**
  * Demonstrates Thread.join behavior.
@@ -14,39 +14,39 @@ import org.junit.Test;
  */
 public class ThreadJoinUnitTest {
 
-    final static Logger LOGGER = Logger.getLogger(ThreadJoinUnitTest.class.getName());
+    private static final Logger LOGGER = LoggerFactory.getLogger(ThreadJoinUnitTest.class);
 
-    class SampleThread extends Thread {
-        public int processingCount = 0;
+    static class SampleThread extends Thread {
+        public int processingCount;
 
         SampleThread(int processingCount) {
             this.processingCount = processingCount;
-            LOGGER.info("Thread " + this.getName() + " created");
+            LOGGER.debug("Thread " + this.getName() + " created");
         }
 
         @Override
         public void run() {
-            LOGGER.info("Thread " + this.getName() + " started");
+            LOGGER.debug("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.");
+                    LOGGER.debug("Thread " + this.getName() + " interrupted.");
                 }
                 processingCount--;
-                LOGGER.info("Inside Thread " + this.getName() + ", processingCount = " + processingCount);
+                LOGGER.debug("Inside Thread " + this.getName() + ", processingCount = " + processingCount);
             }
-            LOGGER.info("Thread " + this.getName() + " exiting");
+            LOGGER.debug("Thread " + this.getName() + " exiting");
         }
     }
 
     @Test
     public void givenNewThread_whenJoinCalled_returnsImmediately() throws InterruptedException {
         Thread t1 = new SampleThread(0);
-        LOGGER.info("Invoking join.");
+        LOGGER.debug("Invoking join.");
         t1.join();
-        LOGGER.info("Returned from join");
-        LOGGER.info("Thread state is" + t1.getState());
+        LOGGER.debug("Returned from join");
+        LOGGER.debug("Thread state is" + t1.getState());
         assertFalse(t1.isAlive());
     }
 
@@ -55,9 +55,9 @@ public class ThreadJoinUnitTest {
       throws InterruptedException {
         Thread t2 = new SampleThread(1);
         t2.start();
-        LOGGER.info("Invoking join.");
+        LOGGER.debug("Invoking join.");
         t2.join();
-        LOGGER.info("Returned from join");
+        LOGGER.debug("Returned from join");
         assertFalse(t2.isAlive());
     }
 

core-java-modules/core-java-concurrency-advanced-2/src/test/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT"/>
+    </root>
+</configuration>

core-java-modules/core-java-concurrency-basic-2/README.md

@@ -12,7 +12,6 @@ This module contains articles about basic Java concurrency
 - [Guide to AtomicMarkableReference](https://www.baeldung.com/java-atomicmarkablereference)
 - [Why are Local Variables Thread-Safe in Java](https://www.baeldung.com/java-local-variables-thread-safe)
 - [How to Stop Execution After a Certain Time in Java](https://www.baeldung.com/java-stop-execution-after-certain-time)
-- [How to Handle InterruptedException in Java](https://www.baeldung.com/java-interrupted-exception)
 - [How to Get the Number of Threads in a Java Process](https://www.baeldung.com/java-get-number-of-threads)
 - [Set the Name of a Thread in Java](https://www.baeldung.com/java-set-thread-name)
-- [[<-- Prev]](/core-java-modules/core-java-concurrency-basic)
+- [[<-- Prev]](../core-java-concurrency-basic)[[Next -->]](../core-java-concurrency-basic-3)

core-java-modules/core-java-concurrency-basic-2/src/main/java/com/baeldung/concurrent/threads/name/CustomThreadName.java

@@ -0,0 +1,70 @@
+package com.baeldung.concurrent.threads.name;
+
+public class CustomThreadName {
+
+    public int currentNumber = 1;
+
+    public int N = 5;
+
+    public static void main(String[] args) {
+
+        CustomThreadName test = new CustomThreadName();
+
+        Thread oddThread = new Thread(() -> {
+            test.printOddNumber();
+            // Uncomment below to set thread name using setName() Method
+            // Thread.currentThread().setName("ODD");
+        }, "ODD");
+        // or Uncomment below to set thread name using setName() Method
+        // oddThread.setName("ODD");
+
+        Thread evenThread = new Thread(() -> {
+            test.printEvenNumber();
+            // Uncomment below to set thread name using setName() Method
+            // Thread.currentThread().setName("EVEN");
+        }, "EVEN");
+
+        // evenThread.setName("EVEN");
+
+        evenThread.start();
+        oddThread.start();
+
+    }
+
+    public void printEvenNumber() {
+        synchronized (this) {
+            while (currentNumber < N) {
+                while (currentNumber % 2 == 1) {
+                    try {
+                        wait();
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                    }
+                }
+                System.out.println(Thread.currentThread()
+                    .getName() + " --> " + currentNumber);
+                currentNumber++;
+                notify();
+            }
+        }
+    }
+
+    public void printOddNumber() {
+        synchronized (this) {
+            while (currentNumber < N) {
+                while (currentNumber % 2 == 0) {
+                    try {
+                        wait();
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                    }
+                }
+                System.out.println(Thread.currentThread()
+                    .getName() + " --> " + currentNumber);
+                currentNumber++;
+                notify();
+            }
+        }
+    }
+
+}

core-java-modules/core-java-concurrency-basic-2/src/main/resources/logback.xml

@@ -7,12 +7,6 @@
         </encoder>
     </appender>
 
-    <logger name="org.springframework" level="WARN" />
-    <logger name="org.springframework.transaction" level="WARN" />
-
-    <!-- in order to debug some marshalling issues, this needs to be TRACE -->
-    <logger name="org.springframework.web.servlet.mvc" level="WARN" />
-
     <root level="INFO">
         <appender-ref ref="STDOUT" />
     </root>

core-java-modules/core-java-concurrency-basic-3/README.md

@@ -0,0 +1,8 @@
+## Core Java Concurrency Basic
+
+This module contains articles about basic Java concurrency.
+
+### Relevant Articles: 
+
+- [How to Handle InterruptedException in Java](https://www.baeldung.com/java-interrupted-exception)
+- [[<-- Prev]](../core-java-concurrency-basic-2)

core-java-modules/core-java-concurrency-basic-3/pom.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>core-java-concurrency-basic-3</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-concurrency-basic-3</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <build>
+        <finalName>core-java-concurrency-basic-3</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+</project>

core-java-modules/core-java-concurrency-basic-3/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

core-java-modules/core-java-concurrency-basic-3/src/test/java/com/baeldung/concurrent/interrupt/InterruptExampleUnitTest.java

@@ -1,7 +1,7 @@
 package com.baeldung.concurrent.interrupt;
 
-import static org.junit.Assert.assertTrue;
 import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
 
@@ -9,7 +9,7 @@ public class InterruptExampleUnitTest {
 
     @Test
     public void whenPropagateException_thenThrowsInterruptedException() {
-        assertThrows(InterruptedException.class, () -> InterruptExample.propagateException());
+        assertThrows(InterruptedException.class, InterruptExample::propagateException);
     }
 
     @Test
@@ -19,7 +19,7 @@ public class InterruptExampleUnitTest {
 
     @Test
     public void whenThrowCustomException_thenContainsExpectedMessage() {
-        Exception exception = assertThrows(CustomInterruptedException.class, () -> InterruptExample.throwCustomException());
+        Exception exception = assertThrows(CustomInterruptedException.class, InterruptExample::throwCustomException);
         String expectedMessage = "This thread was interrupted";
         String actualMessage = exception.getMessage();
 

core-java-modules/core-java-concurrency-collections-2/README.md

@@ -2,4 +2,5 @@
 
 - [Introduction to Lock Striping](https://www.baeldung.com/java-lock-stripping)
 - [Guide to the Java TransferQueue](http://www.baeldung.com/java-transfer-queue)
+- [Java Concurrent HashSet Equivalent to ConcurrentHashMap](https://www.baeldung.com/java-concurrent-hashset-concurrenthashmap)
 - [[<-- Prev]](/core-java-modules/core-java-concurrency-collections)

core-java-modules/core-java-exceptions-4/pom.xml

@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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.exceptions</groupId>
+    <artifactId>core-java-exceptions-4</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-exceptions-4</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <version>${h2.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
+                <configuration>
+                    <compilerArgs>
+<!--                         Comment the arg below to print complete stack trace information -->
+<!--                        <arg>-g:none</arg>-->
+                    </compilerArgs>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <h2.version>1.4.191</h2.version>
+    </properties>
+
+</project>

core-java-modules/core-java-exceptions-4/src/main/java/com/baeldung/exception/arrayindexoutofbounds/ArrayIndexOutOfBoundsExceptionDemo.java

@@ -0,0 +1,31 @@
+package com.baeldung.exception.arrayindexoutofbounds;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class ArrayIndexOutOfBoundsExceptionDemo {
+
+    public static void main(String[] args) {
+        int[] numbers = new int[] { 1, 2, 3, 4, 5 };
+        
+        getArrayElementAtIndex(numbers, 5);
+        getListElementAtIndex(5);
+        addArrayElementsUsingLoop(numbers);
+    }
+
+    public static void addArrayElementsUsingLoop(int[] numbers) {
+        int sum = 0;
+        for (int i = 0; i <= numbers.length; i++) {
+            sum += numbers[i];
+        }
+    }
+
+    public static int getListElementAtIndex(int index) {
+        List<Integer> numbersList = Arrays.asList(1, 2, 3, 4, 5);
+        return numbersList.get(index);
+    }
+
+    public static int getArrayElementAtIndex(int[] numbers, int index) {
+        return numbers[index];
+    }
+}

core-java-modules/core-java-exceptions-4/src/test/java/com/baeldung/exception/arrayindexoutofbounds/ArrayIndexOutOfBoundsExceptionDemoUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.exception.arrayindexoutofbounds;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+public class ArrayIndexOutOfBoundsExceptionDemoUnitTest {
+
+    private static int[] numbers;
+
+    @BeforeAll
+    public static void setUp() {
+        numbers = new int[] { 1, 2, 3, 4, 5 };
+    }
+
+    @Test
+    void givenAnArrayOfSizeFive_whenAccessedElementBeyondRange_thenShouldThrowArrayIndexOutOfBoundsException() {
+        assertThrows(ArrayIndexOutOfBoundsException.class,
+          () -> ArrayIndexOutOfBoundsExceptionDemo.addArrayElementsUsingLoop(numbers));
+    }
+
+    @Test
+    void givenAnArrayOfSizeFive_whenAccessedAnElementAtIndexEqualToSize_thenShouldThrowArrayIndexOutOfBoundsException() {
+        assertThrows(ArrayIndexOutOfBoundsException.class,
+          () -> ArrayIndexOutOfBoundsExceptionDemo.getArrayElementAtIndex(numbers, 5));
+    }
+
+    @Test
+    void givenAListReturnedByArraysAsListMethod_whenAccessedAnElementAtIndexEqualToSize_thenShouldThrowArrayIndexOutOfBoundsException() {
+        assertThrows(ArrayIndexOutOfBoundsException.class,
+          () -> ArrayIndexOutOfBoundsExceptionDemo.getListElementAtIndex(5));
+    }
+}

core-java-modules/core-java-io/src/main/resources/log4j.properties

@@ -1,6 +0,0 @@
-log4j.rootLogger=DEBUG, A1
-
-log4j.appender.A1=org.apache.log4j.ConsoleAppender
-
-log4j.appender.A1.layout=org.apache.log4j.PatternLayout
-log4j.appender.A1.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n

core-java-modules/core-java-io/src/main/resources/log4jstructuraldp.properties

@@ -1,9 +0,0 @@
-
-# Root logger 
-log4j.rootLogger=INFO, file, stdout
-
-# Write to console
-log4j.appender.stdout=org.apache.log4j.ConsoleAppender
-log4j.appender.stdout.Target=System.out
-log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
-log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

core-java-modules/core-java-io/src/main/resources/logback.xml

@@ -7,13 +7,8 @@
         </encoder>
     </appender>
 
-    <logger name="org.springframework" level="WARN" />
-    <logger name="org.springframework.transaction" level="WARN" />
     <logger name="net.sf.jmimemagic" level="WARN" />
 
-    <!-- in order to debug some marshalling issues, this needs to be TRACE -->
-    <logger name="org.springframework.web.servlet.mvc" level="WARN" />
-
     <root level="INFO">
         <appender-ref ref="STDOUT" />
     </root>

core-java-modules/core-java-jndi/README.md

@@ -3,3 +3,4 @@
 
 - [Java Naming and Directory Interface Overview](https://www.baeldung.com/jndi)
 - [LDAP Authentication Using Pure Java](https://www.baeldung.com/java-ldap-auth)
+- [Testing LDAP Connections With Java](https://www.baeldung.com/java-test-ldap-connections)

core-java-modules/core-java-lang-math-2/.gitignore

@@ -2,3 +2,5 @@
 .settings/
 .classpath
 .project
+
+*.log

core-java-modules/core-java-lang-oop-constructors/README.md

@@ -10,3 +10,4 @@ This module contains article about constructors in Java
 - [Throwing Exceptions in Constructors](https://www.baeldung.com/java-constructors-exceptions)
 - [Constructors in Java Abstract Classes](https://www.baeldung.com/java-abstract-classes-constructors)
 - [Java Implicit Super Constructor is Undefined Error](https://www.baeldung.com/java-implicit-super-constructor-is-undefined-error)
+- [Constructor Specification in Java](https://www.baeldung.com/java-constructor-specification)

core-java-modules/core-java-nio-2/README.md

@@ -11,4 +11,5 @@ This module contains articles about core Java non-blocking input and output (IO)
 - [How to Lock a File in Java](https://www.baeldung.com/java-lock-files)
 - [Java NIO DatagramChannel](https://www.baeldung.com/java-nio-datagramchannel)
 - [Java – Path vs File](https://www.baeldung.com/java-path-vs-file)
+- [What Is the Difference Between NIO and NIO.2?](https://www.baeldung.com/java-nio-vs-nio-2)
 - [[<-- Prev]](/core-java-modules/core-java-nio)

core-java-modules/core-java-nio-2/src/test/java/com/baeldung/niovsnio2/NioVsNio2UnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.niovsnio2;
+
+import org.junit.Test;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.stream.Stream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class NioVsNio2UnitTest {
+
+    @Test
+    public void readFromFileUsingFileIO() throws Exception {
+        File file = new File("src/test/resources/nio-vs-nio2.txt");
+        FileInputStream in = new FileInputStream(file);
+        StringBuilder content = new StringBuilder();
+        int data = in.read();
+        while (data != -1) {
+            content.append((char) data);
+            data = in.read();
+        }
+        in.close();
+        assertThat(content.toString()).isEqualTo("Hello from file!");
+    }
+
+    @Test
+    public void readFromFileUsingFileChannel() throws Exception {
+        RandomAccessFile file = new RandomAccessFile("src/test/resources/nio-vs-nio2.txt", "r");
+        FileChannel channel = file.getChannel();
+        StringBuilder content = new StringBuilder();
+
+        ByteBuffer buffer = ByteBuffer.allocate(256);
+        int bytesRead = channel.read(buffer);
+        while (bytesRead != -1) {
+            buffer.flip();
+
+            while (buffer.hasRemaining()) {
+                content.append((char) buffer.get());
+            }
+
+            buffer.clear();
+            bytesRead = channel.read(buffer);
+        }
+        file.close();
+
+        assertThat(content.toString()).isEqualTo("Hello from file!");
+    }
+
+    @Test
+    public void readFromFileUsingNIO2() throws Exception {
+        List<String> strings = Files.readAllLines(Paths.get("src/test/resources/nio-vs-nio2.txt"));
+
+        assertThat(strings.get(0)).isEqualTo("Hello from file!");
+    }
+
+    @Test
+    public void listFilesUsingWalk() throws Exception {
+        Path path = Paths.get("src/test");
+        Stream<Path> walk = Files.walk(path);
+        walk.forEach(System.out::println);
+    }
+}

core-java-modules/core-java-nio-2/src/test/resources/nio-vs-nio2.txt

@@ -0,0 +1 @@
+Hello from file!

core-java-modules/core-java-security-3/README.md

@@ -8,4 +8,6 @@ This module contains articles about core Java Security
 - [Enabling Unlimited Strength Cryptography in Java](https://www.baeldung.com/jce-enable-unlimited-strength)
 - [Initialization Vector for Encryption](https://www.baeldung.com/java-encryption-iv)
 - [HMAC in Java](https://www.baeldung.com/java-hmac)
+- [Generating a Secure AES Key in Java](https://www.baeldung.com/java-secure-aes-key)
+- [Computing an X509 Certificate’s Thumbprint in Java](https://www.baeldung.com/java-x509-certificate-thumbprint)
 - More articles: [[<-- prev]](/core-java-modules/core-java-security-2)

core-java-modules/core-java-serialization/src/test/java/com/baeldung/externalizable/ExternalizableUnitTest.java

@@ -1,14 +1,29 @@
 package com.baeldung.externalizable;
 
+import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 
 import java.io.*;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
 public class ExternalizableUnitTest {
 
-    private final static String OUTPUT_FILE = "externalizable.txt";
+    private final static String OUTPUT_FILE_NAME = "externalizable.txt";
+
+    @Rule
+    public TemporaryFolder tempFolder = new TemporaryFolder();
+
+    private File outputFile;
+
+    @Before
+    public void setUp() throws Exception {
+        outputFile = tempFolder.newFile(OUTPUT_FILE_NAME);
+    }
 
     @Test
     public void whenSerializing_thenUseExternalizable() throws IOException, ClassNotFoundException {
@@ -18,7 +33,7 @@ public class ExternalizableUnitTest {
         c.setCode(374);
         c.setName("Armenia");
 
-        FileOutputStream fileOutputStream = new FileOutputStream(OUTPUT_FILE);
+        FileOutputStream fileOutputStream = new FileOutputStream(outputFile);
         ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
         c.writeExternal(objectOutputStream);
 
@@ -26,7 +41,7 @@ public class ExternalizableUnitTest {
         objectOutputStream.close();
         fileOutputStream.close();
 
-        FileInputStream fileInputStream = new FileInputStream(OUTPUT_FILE);
+        FileInputStream fileInputStream = new FileInputStream(outputFile);
         ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
 
         Country c2 = new Country();
@@ -35,8 +50,8 @@ public class ExternalizableUnitTest {
         objectInputStream.close();
         fileInputStream.close();
 
-        assertTrue(c2.getCode() == c.getCode());
-        assertTrue(c2.getName().equals(c.getName()));
+        assertEquals(c2.getCode(), c.getCode());
+        assertEquals(c2.getName(), c.getName());
     }
 
     @Test
@@ -49,7 +64,7 @@ public class ExternalizableUnitTest {
         r.setClimate("Mediterranean");
         r.setPopulation(120.000);
 
-        FileOutputStream fileOutputStream = new FileOutputStream(OUTPUT_FILE);
+        FileOutputStream fileOutputStream = new FileOutputStream(outputFile);
         ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
         r.writeExternal(objectOutputStream);
 
@@ -57,7 +72,7 @@ public class ExternalizableUnitTest {
         objectOutputStream.close();
         fileOutputStream.close();
 
-        FileInputStream fileInputStream = new FileInputStream(OUTPUT_FILE);
+        FileInputStream fileInputStream = new FileInputStream(outputFile);
         ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
 
         Region r2 = new Region();
@@ -66,6 +81,6 @@ public class ExternalizableUnitTest {
         objectInputStream.close();
         fileInputStream.close();
 
-        assertTrue(r2.getPopulation() == null);
+        assertNull(r2.getPopulation());
     }
 }

core-java-modules/core-java-serialization/src/test/java/com/baeldung/serialization/PersonUnitTest.java

@@ -1,36 +1,54 @@
 package com.baeldung.serialization;
 
+import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 
+import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 public class PersonUnitTest {
 
+    @Rule
+    public TemporaryFolder tempFolder = new TemporaryFolder();
+
+    private File outputFile;
+
+    private File outputFile2;
+
+    @Before
+    public void setUp() throws Exception {
+        outputFile = tempFolder.newFile("yourfile.txt");
+        outputFile2 = tempFolder.newFile("yourfile2.txt");
+    }
+
     @Test
     public void whenSerializingAndDeserializing_ThenObjectIsTheSame() throws IOException, ClassNotFoundException {
         Person p = new Person();
         p.setAge(20);
         p.setName("Joe");
 
-        FileOutputStream fileOutputStream = new FileOutputStream("yofile.txt");
+        FileOutputStream fileOutputStream = new FileOutputStream(outputFile);
         ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
         objectOutputStream.writeObject(p);
         objectOutputStream.flush();
         objectOutputStream.close();
 
-        FileInputStream fileInputStream = new FileInputStream("yofile.txt");
+        FileInputStream fileInputStream = new FileInputStream(outputFile);
         ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
         Person p2 = (Person) objectInputStream.readObject();
         objectInputStream.close();
 
-        assertTrue(p2.getAge() == p.getAge());
-        assertTrue(p2.getName().equals(p.getName()));
+        assertEquals(p2.getAge(), p.getAge());
+        assertEquals(p2.getName(), p.getName());
     }
 
     @Test
@@ -46,19 +64,19 @@ public class PersonUnitTest {
         e.setPerson(p);
         e.setAddress(a);
 
-        FileOutputStream fileOutputStream = new FileOutputStream("yofile2.txt");
+        FileOutputStream fileOutputStream = new FileOutputStream(outputFile2);
         ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
         objectOutputStream.writeObject(e);
         objectOutputStream.flush();
         objectOutputStream.close();
 
-        FileInputStream fileInputStream = new FileInputStream("yofile2.txt");
+        FileInputStream fileInputStream = new FileInputStream(outputFile2);
         ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
         Employee e2 = (Employee) objectInputStream.readObject();
         objectInputStream.close();
 
-        assertTrue(e2.getPerson().getAge() == e.getPerson().getAge());
-        assertTrue(e2.getAddress().getHouseNumber() == (e.getAddress().getHouseNumber()));
+        assertEquals(e2.getPerson().getAge(), e.getPerson().getAge());
+        assertEquals(e2.getAddress().getHouseNumber(), (e.getAddress().getHouseNumber()));
     }
 
 }

core-java-modules/core-java-serialization/src/test/java/com/baeldung/serialization/SerializationUnitTest.java

@@ -4,6 +4,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
@@ -13,17 +14,32 @@ import java.io.ObjectOutputStream;
 import java.io.Serializable;
 
 import org.apache.commons.lang3.SerializationUtils;
+import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 
 import com.baeldung.util.MySerializationUtils;
+import org.junit.rules.TemporaryFolder;
 
 public class SerializationUnitTest {
 
+    private final static String OUTPUT_FILE_NAME = "yourfile.txt";
+
+    @Rule
+    public TemporaryFolder tempFolder = new TemporaryFolder();
+
+    private File outputFile;
+
+    @Before
+    public void setUp() throws Exception {
+        outputFile = tempFolder.newFile(OUTPUT_FILE_NAME);
+    }
+
     @Test(expected = NotSerializableException.class)
     public void whenSerializing_ThenThrowsError() throws IOException {
         Address address = new Address();
         address.setHouseNumber(10);
-        FileOutputStream fileOutputStream = new FileOutputStream("yofile.txt");
+        FileOutputStream fileOutputStream = new FileOutputStream(outputFile);
         try (ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream)) {
             objectOutputStream.writeObject(address);
         }
@@ -35,12 +51,12 @@ public class SerializationUnitTest {
         p.setAge(20);
         p.setName("Joe");
 
-        FileOutputStream fileOutputStream = new FileOutputStream("yofile.txt");
+        FileOutputStream fileOutputStream = new FileOutputStream(outputFile);
         try (ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream)) {
             objectOutputStream.writeObject(p);
         }
 
-        FileInputStream fileInputStream = new FileInputStream("yofile.txt");
+        FileInputStream fileInputStream = new FileInputStream(outputFile);
         try (ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream)) {
             Person p2 = (Person) objectInputStream.readObject();
             assertEquals(p2.getAge(), p.getAge());

core-java-modules/core-java-string-algorithms-3/README.md

@@ -4,6 +4,7 @@ This module contains articles about string-related algorithms.
 
 ### Relevant Articles:
 
+- [Generating a Java String of N Repeated Characters](https://www.baeldung.com/java-string-of-repeated-characters)
 - [Check if Two Strings are Anagrams in Java](https://www.baeldung.com/java-strings-anagrams)
 - [Email Validation in Java](https://www.baeldung.com/java-email-validation-regex)
 - [Check if the First Letter of a String is Uppercase](https://www.baeldung.com/java-check-first-letter-uppercase)

core-java-modules/core-java-string-algorithms-3/pom.xml

@@ -49,8 +49,9 @@
     </build>
 
     <properties>
+        <maven.compiler.source>11</maven.compiler.source>
+        <maven.compiler.target>11</maven.compiler.target>
         <validator.version>1.7</validator.version>
         <apache-commons-lang3.version>3.12.0</apache-commons-lang3.version>
     </properties>
-
 </project>

core-java-modules/core-java-string-algorithms-3/src/test/java/com/baeldung/repeatedcharstring/RepeatedCharacterStringUnitTest.java

@@ -19,6 +19,18 @@ class RepeatedCharacterStringUnitTest {
     private static final String EXPECTED_STRING = "aaaaaaa";
     private static final int N = 7;
 
+    @Test
+    void givenSingleCharacterString_whenRepeat_thenStringCreated() {
+        String newString = "a".repeat(N);
+        assertEquals(EXPECTED_STRING, newString);
+    }
+
+    @Test
+    void givenMultiCharacterString_whenRepeat_thenStringCreated() {
+        String newString = "-->".repeat(5);
+        assertEquals("-->-->-->-->-->", newString);
+    }
+
     @Test
     void givenString_whenStringBuilderUsed_thenStringCreated() {
         StringBuilder builder = new StringBuilder(N);

core-java-modules/multimodulemavenproject/README.md

@@ -1,3 +1,4 @@
 ## Relevant Articles
 
 - [Multi-Module Maven Application with Java Modules](https://www.baeldung.com/maven-multi-module-project-java-jpms)
+- [Importing Maven Project into Eclipse](https://www.baeldung.com/maven-import-eclipse)

core-java-modules/pom.xml

@@ -46,6 +46,7 @@
         <module>core-java-concurrency-advanced-4</module>
         <module>core-java-concurrency-basic</module>
         <module>core-java-concurrency-basic-2</module>
+        <module>core-java-concurrency-basic-3</module>
         <module>core-java-concurrency-collections</module>
         <module>core-java-concurrency-collections-2</module>
         <module>core-java-console</module>
@@ -55,6 +56,7 @@
         <module>core-java-exceptions</module>
         <module>core-java-exceptions-2</module>
         <module>core-java-exceptions-3</module>
+        <module>core-java-exceptions-4</module>
         <module>core-java-function</module>
         <module>core-java-functional</module>
         <module>core-java-io</module>
@@ -107,7 +109,6 @@
         <module>core-java-streams-4</module>
         <module>core-java-string-algorithms</module>
         <module>core-java-string-algorithms-2</module>
-        <module>core-java-string-algorithms-3</module>
         <module>core-java-string-apis</module>
         <module>core-java-string-conversions</module>
         <module>core-java-string-conversions-2</module>

feign/README.md

@@ -5,4 +5,5 @@ This module contains articles about Feign
 ### Relevant Articles:
 
 - [Intro to Feign](https://www.baeldung.com/intro-to-feign)
+- [Retrying Feign Calls](https://www.baeldung.com/feign-retry)
 

feign/src/main/java/com/baeldung/feign/retry/Custom5xxErrorDecoder.java

@@ -0,0 +1,27 @@
+package com.baeldung.feign.retry;
+
+
+import feign.FeignException;
+import feign.Response;
+import feign.RetryableException;
+import feign.codec.ErrorDecoder;
+
+import static feign.FeignException.errorStatus;
+
+public class Custom5xxErrorDecoder implements ErrorDecoder {
+    @Override
+    public Exception decode(String methodKey, Response response) {
+        FeignException exception = errorStatus(methodKey, response);
+        int status = response.status();
+        if (status >= 500) {
+            return new RetryableException(
+              response.status(),
+              exception.getMessage(),
+              response.request().httpMethod(),
+              exception,
+              null,
+              response.request());
+        }
+        return exception;
+    }
+}

feign/src/main/java/com/baeldung/feign/retry/NaiveRetryer.java

@@ -0,0 +1,21 @@
+package com.baeldung.feign.retry;
+
+import feign.RetryableException;
+import feign.Retryer;
+
+public class NaiveRetryer implements feign.Retryer {
+    @Override
+    public void continueOrPropagate(RetryableException e) {
+        try {
+            Thread.sleep(1000L);
+        } catch (InterruptedException ex) {
+            Thread.currentThread().interrupt();
+            throw e;
+        }
+    }
+
+    @Override
+    public Retryer clone() {
+        return new NaiveRetryer();
+    }
+}

feign/src/main/java/com/baeldung/feign/retry/ResilientFeignClientBuilder.java

@@ -0,0 +1,28 @@
+package com.baeldung.feign.retry;
+
+import com.baeldung.feign.clients.BookClient;
+import feign.Feign;
+import feign.Logger;
+import feign.Retryer;
+import feign.gson.GsonDecoder;
+import feign.gson.GsonEncoder;
+import feign.okhttp.OkHttpClient;
+import feign.slf4j.Slf4jLogger;
+import lombok.Getter;
+
+import java.util.concurrent.TimeUnit;
+
+@Getter
+public class ResilientFeignClientBuilder {
+    public BookClient bookClient = createClient(BookClient.class, "http://localhost:8081/api/books");
+
+    public static <T> T createClient(Class<T> type, String uri) {
+        return Feign.builder()
+          .client(new OkHttpClient())
+          .encoder(new GsonEncoder())
+          .decoder(new GsonDecoder())
+          .retryer(new Retryer.Default(100L, TimeUnit.SECONDS.toMillis(3L), 5))
+          .errorDecoder(new Custom5xxErrorDecoder())
+          .target(type, uri);
+    }
+}

feign/src/test/java/com/baeldung/feign/retry/Custom5xxErrorDecoderUnitTest.java

@@ -0,0 +1,51 @@
+package com.baeldung.feign.retry;
+
+import feign.*;
+import feign.codec.ErrorDecoder;
+import org.jetbrains.annotations.NotNull;
+import org.junit.Test;
+
+import java.nio.charset.Charset;
+import java.util.Collection;
+import java.util.HashMap;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class Custom5xxErrorDecoderUnitTest {
+    @Test
+    public void given5xxResponse_whenDecode_thenReturnRetryableException() {
+        // given
+        ErrorDecoder decoder = new Custom5xxErrorDecoder();
+        Response response = responseStub(500);
+
+        // when
+        Exception exception = decoder.decode("GET", response);
+
+        // then
+        assertTrue(exception instanceof RetryableException);
+    }
+
+    @Test
+    public void given4xxResponse_whenDecode_thenReturnFeignException() {
+        // given
+        ErrorDecoder decoder = new Custom5xxErrorDecoder();
+        Response response = responseStub(400);
+
+        // when
+        Exception exception = decoder.decode("GET", response);
+
+        // then
+        assertTrue(exception instanceof FeignException);
+        assertFalse(exception instanceof RetryableException);
+    }
+
+    @NotNull
+    private Response responseStub(int status) {
+        return Response.builder()
+          .request(Request.create(
+            Request.HttpMethod.GET, "url", new HashMap<>(), new byte[0], Charset.defaultCharset(), new RequestTemplate()))
+          .status(status)
+          .build();
+    }
+}

gradle/maven-to-gradle/README.md

@@ -0,0 +1,3 @@
+## Relevant Articles:
+
+[Convert a Maven Build to Gradle](https://www.baeldung.com/maven-convert-to-gradle)

graphql/graphql-dgs/README.md

@@ -0,0 +1,7 @@
+## GraphQL Domain Graph Service (DGS)
+
+This module contains articles about GraphQL using the Netflix Domain Graph Service (DGS).
+
+## Relevant articles:
+
+- [An Introduction to Domain Graph Service (DGS) Framework](https://www.baeldung.com/spring-boot-domain-graph-service)

graphql/graphql-dgs/pom.xml

@@ -0,0 +1,91 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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.graphql-dgs</groupId>
+    <artifactId>graphql-dgs</artifactId>
+    <version>1.0</version>
+    <name>graphql-dgs</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../..</relativePath>
+    </parent>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>com.netflix.graphql.dgs</groupId>
+                <artifactId>graphql-dgs-platform-dependencies</artifactId>
+                <version>4.1.0</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+            <version>2.6.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <version>2.6.2</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>com.netflix.graphql.dgs.codegen</groupId>
+            <artifactId>graphql-dgs-codegen-client-core</artifactId>
+            <version>5.1.14</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+            <version>2.6.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.netflix.graphql.dgs</groupId>
+            <artifactId>graphql-dgs-spring-boot-starter</artifactId>
+            <version>4.9.15</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <version>2.6.2</version>
+            </plugin>
+            <plugin>
+                <groupId>io.github.deweyjose</groupId>
+                <artifactId>graphqlcodegen-maven-plugin</artifactId>
+                <version>1.14</version>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>generate</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <schemaPaths>
+                        <param>src/main/resources/schema/schema.graphqls</param>
+                    </schemaPaths>
+                    <packageName>com.bealdung.graphqldgs.generated</packageName>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

graphql/graphql-dgs/src/main/java/com/bealdung/graphqlDGS/Album.java

@@ -0,0 +1,25 @@
+package com.bealdung.graphqlDGS;
+
+public class Album {
+    private final String title;
+    private final String artist;
+    private final Integer recordNo;
+
+    public Album(String title, String artist, Integer recordNo) {
+        this.title = title;
+        this.recordNo = recordNo;
+        this.artist = artist;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getArtist() {
+        return artist;
+    }
+
+    public Integer getRecordNo() {
+        return recordNo;
+    }
+}

graphql/graphql-dgs/src/main/java/com/bealdung/graphqlDGS/AlbumsDataFetcher.java

@@ -0,0 +1,28 @@
+package com.bealdung.graphqlDGS;
+
+import com.netflix.graphql.dgs.DgsComponent;
+import com.netflix.graphql.dgs.DgsQuery;
+import com.netflix.graphql.dgs.InputArgument;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+@DgsComponent
+public class AlbumsDataFetcher {
+
+    private final List<Album> albums = Arrays.asList(
+      new Album("Rumours", "Fleetwood Mac", 20),
+      new Album("What's Going On", "Marvin Gaye", 10),
+      new Album("Pet Sounds", "The Beach Boys", 12)
+    );
+
+    @DgsQuery
+    public List<Album> albums(@InputArgument String titleFilter) {
+        if(titleFilter == null) {
+            return albums;
+        }
+        return albums.stream()
+                .filter(s -> s.getTitle().contains(titleFilter))
+                .collect(Collectors.toList());
+    }
+}

graphql/graphql-dgs/src/main/java/com/bealdung/graphqlDGS/Application.java

@@ -0,0 +1,13 @@
+package com.bealdung.graphqlDGS;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+
+}

graphql/graphql-dgs/src/main/resources/application.properties

@@ -0,0 +1 @@
+server.servlet.context-path=

graphql/graphql-dgs/src/main/resources/schema/schema.graphqls

@@ -0,0 +1,9 @@
+type Query {
+    albums(titleFilter: String): [Album]
+}
+
+type Album {
+    title: String
+    artist: String
+    recordNo: Int
+}

java-collections-maps-3/README.md

@@ -6,3 +6,4 @@
 - [Optimizing HashMap’s Performance](https://www.baeldung.com/java-hashmap-optimize-performance)
 - [Update the Value Associated With a Key in a HashMap](https://www.baeldung.com/java-hashmap-update-value-by-key)
 - [Java Map – keySet() vs. entrySet() vs. values() Methods](https://www.baeldung.com/java-map-entries-methods)
+- [Java IdentityHashMap Class and Its Use Cases](https://www.baeldung.com/java-identityhashmap)

java-spi/exchange-rate-impl/src/main/java/com/baeldung/rate/impl/YahooQuoteManagerImpl.java

@@ -24,7 +24,7 @@ public class YahooQuoteManagerImpl implements QuoteManager {
 
         StringBuilder sb = new StringBuilder();
         Currency.getAvailableCurrencies().forEach(currency -> {
-            if (!currency.equals(currency.getCurrencyCode())) {
+            if (!baseCurrency.equals(currency.getCurrencyCode())) {
                 sb.append(baseCurrency).append(currency.getCurrencyCode()).append("=X").append(",");
             }
         });

javafx/README.md

@@ -3,6 +3,8 @@
 This module contains articles about JavaFX.
 
 ### Relevant Articles:
+
 - [Introduction to JavaFX](https://www.baeldung.com/javafx)
 - [Display Custom Items in JavaFX ListView](https://www.baeldung.com/javafx-listview-display-custom-items)
+- [Adding EventHandler to JavaFX Button](https://www.baeldung.com/javafx-button-eventhandler)
 

javafx/src/main/java/com/baeldung/button/eventhandler/ButtonEventHandlerController.java

@@ -0,0 +1,64 @@
+package com.baeldung.button.eventhandler;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javafx.event.ActionEvent;
+import javafx.event.EventHandler;
+import javafx.fxml.FXML;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.effect.DropShadow;
+import javafx.scene.effect.Effect;
+import javafx.scene.input.MouseButton;
+import javafx.scene.input.MouseEvent;
+import javafx.scene.text.Font;
+
+public class ButtonEventHandlerController {
+
+    private static final Logger logger = LoggerFactory.getLogger(ButtonEventHandlerController.class);
+
+    @FXML
+    private Button button;
+
+    @FXML
+    private Label label;
+
+    @FXML
+    private void initialize() {
+        button.setText("Click me");
+
+        handleClickEvent();
+        handleHoverEffect();
+        reuseRightClickEventHandler();
+    }
+
+    private void handleClickEvent() {
+        button.setOnAction(new EventHandler<ActionEvent>() {
+            @Override
+            public void handle(ActionEvent event) {
+                logger.info("OnAction {}", event);
+            }
+        });
+
+        button.setOnAction(event -> logger.info("OnAction {}", event));
+        button.setOnAction(event -> logger.info("OnAction2 {}", event));
+    }
+
+    private void handleHoverEffect() {
+        Effect shadow = new DropShadow();
+        button.setOnMouseEntered(e -> button.setEffect(shadow));
+        button.setOnMouseExited(e -> button.setEffect(null));
+    }
+
+    private void reuseRightClickEventHandler() {
+        EventHandler<MouseEvent> rightClickHandler = event -> {
+            if (MouseButton.SECONDARY.equals(event.getButton())) {
+                button.setFont(new Font(button.getFont()
+                    .getSize() + 1));
+            }
+        };
+        button.setOnMousePressed(rightClickHandler);
+        label.setOnMousePressed(rightClickHandler);
+    }
+}

javafx/src/main/java/com/baeldung/button/eventhandler/Main.java

@@ -0,0 +1,24 @@
+package com.baeldung.button.eventhandler;
+
+import javafx.application.Application;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Scene;
+import javafx.scene.layout.Pane;
+import javafx.stage.Stage;
+
+public class Main extends Application {
+
+    public static void main(String[] args) {
+        launch(args);
+    }
+
+    @Override
+    public void start(Stage primaryStage) throws Exception {
+        FXMLLoader loader = new FXMLLoader(getClass().getResource("/button_event-handler.fxml"));
+        Pane page = loader.load();
+
+        primaryStage.setTitle("Button event handler");
+        primaryStage.setScene(new Scene(page));
+        primaryStage.show();
+    }
+}

javafx/src/main/resources/button_event-handler.fxml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.control.*?>
+<?import javafx.scene.layout.*?>
+<BorderPane xmlns:fx="http://javafx.com/fxml"
+    xmlns="http://javafx.com/javafx"
+    fx:controller="com.baeldung.button.eventhandler.ButtonEventHandlerController"
+    prefHeight="200.0" prefWidth="300.0">
+    <center>
+        <Button fx:id="button" HBox.hgrow="ALWAYS"/>
+    </center>
+    
+    <bottom>
+        <Label fx:id="label" text="Test label"/>
+    </bottom>
+</BorderPane>

javaxval/pom.xml

@@ -15,7 +15,7 @@
 
     <dependencies>
         <dependency>
-            <groupId>org.hibernate</groupId>
+            <groupId>org.hibernate.validator</groupId>
             <artifactId>hibernate-validator</artifactId>
             <version>${hibernate-validator.version}</version>
         </dependency>
@@ -36,8 +36,43 @@
         </dependency>
     </dependencies>
 
+    <!-- uncomment in order to enable Hibernate Validator Anotation Processor -->
+    <!--
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven.compiler.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                    <fork>true</fork>
+                    <compilerArgs>
+                        <arg>-Averbose=true</arg>
+                        <arg>-AmethodConstraintsSupported=true</arg>
+                        <arg>-AdiagnosticKind=ERROR</arg>
+                    </compilerArgs>
+                    <annotationProcessorPaths>
+                        <path>
+                            <groupId>org.hibernate.validator</groupId>
+                            <artifactId>hibernate-validator-annotation-processor</artifactId>
+                            <version>${hibernate-validator.ap.version}</version>
+                        </path>
+                    </annotationProcessorPaths>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    -->
+
     <properties>
         <hibernate-validator.version>6.0.13.Final</hibernate-validator.version>
+        <hibernate-validator.ap.version>6.2.0.Final</hibernate-validator.ap.version>
+        <maven.compiler.version>3.6.1</maven.compiler.version>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
         <javax.el.version>3.0.0</javax.el.version>
         <org.springframework.version>5.0.2.RELEASE</org.springframework.version>
     </properties>

javaxval/src/main/java/com/baeldung/javaxval/hibernate/validator/ap/Message.java

@@ -0,0 +1,95 @@
+package com.baeldung.javaxval.hibernate.validator.ap;
+
+import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.NotNull;
+import javax.validation.constraints.Past;
+import java.util.List;
+import java.util.Optional;
+
+public class Message {
+
+    @NotNull(message = "Content cannot be null")
+    private String content;
+
+    private boolean isDelivered;
+
+    private List<@NotBlank String> recipients;
+
+    // uncomment in order to trigger AP annotation detection
+    // The annotation @Past is disallowed for this data type.
+    // @Past
+    private String createdAt;
+
+    public String getContent() {
+        return content;
+    }
+
+    public Message(String content, boolean isDelivered, List<@NotBlank String> recipients, String createdAt) {
+        this.content = content;
+        this.isDelivered = isDelivered;
+        this.recipients = recipients;
+        this.createdAt = createdAt;
+    }
+
+    // uncomment in order to trigger AP annotation detection
+    // The annotation @Min is disallowed for the return type of this method.
+    // @Min(3)
+    public boolean broadcast() {
+        // setup a logic
+        // to send to recipients
+        return true;
+    }
+
+    // uncomment in order to trigger AP annotation detection
+    // Void methods may not be annotated with constraint annotations.
+    // @NotNull
+    public void archive() {
+        // archive the message
+    }
+
+    // uncomment in order to trigger AP annotation detection
+    // Constraint annotations must not be specified at methods, which are no valid JavaBeans getter methods.
+    // NOTE: add <arg>-AmethodConstraintsSupported=false</arg> to compiler args before
+    // @AssertTrue
+    public boolean delete() {
+        // delete the message
+        return false;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    public boolean isDelivered() {
+        return isDelivered;
+    }
+
+    public void setDelivered(boolean delivered) {
+        isDelivered = delivered;
+    }
+
+    public List<String> getRecipients() {
+        return recipients;
+    }
+
+    public void setRecipients(List<String> recipients) {
+        this.recipients = recipients;
+    }
+
+    public void setCreatedAt(String createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public String getName() {
+        return content;
+    }
+
+    public void setName(String content) {
+        this.content = content;
+    }
+
+    public Optional<@Past String> getCreatedAt() {
+        return Optional.ofNullable(createdAt);
+    }
+
+}

logging-modules/log4j2/src/main/java/com/baeldung/logging/log4j2threadinfo/Log4j2ThreadInfo.java

@@ -0,0 +1,18 @@
+package com.baeldung.logging.log4j2threadinfo;
+
+import java.util.stream.IntStream;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+public class Log4j2ThreadInfo {
+    private static final Logger logger = LogManager.getLogger(Log4j2ThreadInfo.class);
+
+    public static void main(String[] args) {
+        IntStream.range(0, 5).forEach(i -> {
+            Runnable runnable = () -> logger.info("Logging info");
+            Thread thread = new Thread(runnable);
+            thread.start();
+        });
+    }
+}

logging-modules/log4j2/src/main/resources/log4j2.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration>
+    <Properties>
+        <Property name="LOG_PATTERN">
+            %d{yyyy-MM-dd HH:mm:ss.SSS} --- thread_id="%tid" thread_name="%tn" thread_priority="%tp" --- [%p] %m%n
+        </Property>
+    </Properties>
+    <Appenders>
+        <RollingFile name="RollingName" filename="logs/app.log"
+                     filePattern="$${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.log">
+            <PatternLayout>
+                <Pattern>${LOG_PATTERN}</Pattern>
+            </PatternLayout>
+            <Policies>
+                <SizeBasedTriggeringPolicy size="20MB"/>
+            </Policies>
+        </RollingFile>
+        <Console name="Console" target="SYSTEM_OUT">
+            <PatternLayout pattern="${LOG_PATTERN}"/>
+        </Console>
+    </Appenders>
+    <Loggers>
+        <Logger name="com.baeldung.logging.log4j2threadinfo" level="trace">
+            <AppenderRef ref="Console"/>
+        </Logger>
+        <Root level="error">
+            <AppenderRef ref="RollingName"/>
+        </Root>
+    </Loggers>
+</Configuration>

parent-boot-2/pom.xml

@@ -88,7 +88,7 @@
         <rest-assured.version>3.3.0</rest-assured.version>
         <!-- plugins -->
         <thin.version>1.0.22.RELEASE</thin.version>
-        <spring-boot.version>2.6.1</spring-boot.version>
+        <spring-boot.version>2.6.3</spring-boot.version>
         <aspectjweaver.version>1.9.1</aspectjweaver.version>
     </properties>
 

persistence-modules/core-java-persistence-2/src/main/java/com/baeldung/connectionstatus/ConnectionValidation.java

@@ -0,0 +1,65 @@
+package com.baeldung.connectionstatus;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+
+public class ConnectionValidation
+{
+
+    public static Connection getConnection()
+            throws Exception
+    {
+        Class.forName("org.h2.Driver");
+        String url = "jdbc:h2:mem:testdb";
+        return DriverManager.getConnection(url, "user", "password");
+    }
+
+    public static void runIfOpened(Connection connection)
+            throws SQLException
+    {
+        if (connection != null && !connection.isClosed()) {
+            // run sql statements
+        }
+        else {
+            // handle closed connection
+        }
+    }
+
+    public static void runIfValid(Connection connection)
+            throws SQLException
+    {
+        // Try to validate connection with a 5 seconds timeout
+        if (connection.isValid(5)) {
+            // run sql statements
+        }
+        else {
+            // handle invalid connection
+        }
+    }
+
+    public static void runIfConnectionValid(Connection connection)
+    {
+        if (isConnectionValid(connection)) {
+            // run sql statements
+        }
+        else {
+            // handle invalid connection
+        }
+    }
+
+    public static boolean isConnectionValid(Connection connection)
+    {
+        try {
+            if (connection != null && !connection.isClosed()) {
+                // Running a simple validation query
+                connection.prepareStatement("SELECT 1");
+                return true;
+            }
+        }
+        catch (SQLException e) {
+            // log some useful data here
+        }
+        return false;
+    }
+}

persistence-modules/core-java-persistence-2/src/test/java/com/baeldung/connectionstatus/ConnectionValidationUnitTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.connectionstatus;
+
+import org.junit.jupiter.api.Test;
+
+import java.sql.Connection;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class ConnectionValidationUnitTest
+{
+    @Test
+    void givenConnectionObject_whenCreated_thenIsNotClosed()
+            throws Exception
+    {
+        Connection connection = ConnectionValidation.getConnection();
+        assertNotNull(connection);
+        assertFalse(connection.isClosed());
+    }
+
+    @Test
+    void givenConnectionObject_whenCreated_thenIsValid()
+            throws Exception
+    {
+        Connection connection = ConnectionValidation.getConnection();
+        assertTrue(connection.isValid(0));
+    }
+
+    @Test
+    void givenConnectionObject_whenValidated_thenIsValid()
+            throws Exception
+    {
+        Connection connection = ConnectionValidation.getConnection();
+        assertTrue(ConnectionValidation.isConnectionValid(connection));
+    }
+
+}

persistence-modules/java-cassandra/README.md

@@ -1,4 +1,6 @@
 ### Relevant Articles:
+
+- [Cassandra Batch in Cassandra Query Language and Java](https://www.baeldung.com/java-cql-cassandra-batch)
 - [A Guide to Cassandra with Java](http://www.baeldung.com/cassandra-with-java)
 - [Intro to DataStax Java Driver for Apache Cassandra](https://www.baeldung.com/cassandra-datastax-java-driver)
 - [CQL Data Types](https://www.baeldung.com/cassandra-data-types)

persistence-modules/java-mongodb/README.md

@@ -12,3 +12,4 @@ This module contains articles about MongoDB in Java.
 - [MongoDB Aggregations Using Java](https://www.baeldung.com/java-mongodb-aggregations)
 - [BSON to JSON Document Conversion in Java](https://www.baeldung.com/java-convert-bson-to-json)
 - [How to Check Field Existence in MongoDB?](https://www.baeldung.com/mongodb-check-field-exists)
+- [Get Last Inserted Document ID in MongoDB With Java Driver](https://www.baeldung.com/java-mongodb-last-inserted-id)

persistence-modules/java-mongodb/src/main/java/com/baeldung/mongo/objectid/RetrieveIdExample.java

@@ -0,0 +1,57 @@
+package com.baeldung.mongo.objectid;
+
+import java.util.Date;
+
+import org.bson.Document;
+import org.bson.types.ObjectId;
+
+import com.mongodb.MongoClient;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoDatabase;
+
+public class RetrieveIdExample {
+
+    public static void main(String[] args) {
+        
+        try ( MongoClient mongoClient = new MongoClient("localhost", 27017) ) {
+            
+            MongoDatabase database = mongoClient.getDatabase("myMongoDb");        
+            MongoCollection<Document> collection = database.getCollection("example");
+ 
+//          Create document with user-generated ID
+            ObjectId generatedId = new ObjectId();
+            
+            System.out.println(generatedId.toString());                    
+            
+            Document document = new Document();
+            document.put("_id", generatedId);
+            document.put("name", "Shubham");
+            document.put("company", "Baeldung");
+            collection.insertOne(document);
+            
+//          Check that the ID of the document is still the one we set 
+            System.out.println(document.getObjectId("_id").equals(generatedId));
+            
+            
+//          Create a second document by injecting the ID in the constructor
+            
+            ObjectId generatedId2 = ObjectId.get();
+            
+            Document document2 = new Document("_id", generatedId2);
+            document2.put("name", "Shubham");
+            document2.put("company", "Baeldung");
+            collection.insertOne(document2);
+                        
+            Date creationDate = generatedId.getDate();
+            System.out.println(creationDate);
+            
+            int timestamp = generatedId.getTimestamp();            
+            
+        } catch (Exception e) {
+            
+            System.out.println(e.getMessage());
+            e.printStackTrace();
+        }
+    }
+
+}

persistence-modules/spring-data-cassandra/src/test/java/com/baeldung/SpringContextTest.java

@@ -47,8 +47,8 @@ public class SpringContextTest {
     }
 
     @Before
-    public void createTable() throws InterruptedException, TTransportException, ConfigurationException, IOException {
-        adminTemplate.createTable(true, CqlIdentifier.cqlId(DATA_TABLE_NAME), Book.class, new HashMap<String, Object>());
+    public void createTable() {
+        adminTemplate.createTable(true, CqlIdentifier.cqlId(DATA_TABLE_NAME), Book.class, new HashMap<>());
     }
 
 	@Test

persistence-modules/spring-data-cassandra/src/test/java/com/baeldung/spring/data/cassandra/repository/BookRepositoryLiveTest.java

@@ -1,17 +1,15 @@
 package com.baeldung.spring.data.cassandra.repository;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotEquals;
-
-import java.io.IOException;
-import java.util.HashMap;
-
+import com.baeldung.spring.data.cassandra.config.CassandraConfig;
 import com.baeldung.spring.data.cassandra.model.Book;
+import com.datastax.driver.core.Cluster;
+import com.datastax.driver.core.Session;
+import com.datastax.driver.core.utils.UUIDs;
+import com.google.common.collect.ImmutableSet;
 import org.apache.cassandra.exceptions.ConfigurationException;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.thrift.transport.TTransportException;
-import com.baeldung.spring.data.cassandra.config.CassandraConfig;
 import org.cassandraunit.utils.EmbeddedCassandraServerHelper;
 import org.junit.After;
 import org.junit.AfterClass;
@@ -25,15 +23,24 @@ import org.springframework.data.cassandra.core.CassandraAdminOperations;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 
-import com.datastax.driver.core.Cluster;
-import com.datastax.driver.core.Session;
-import com.datastax.driver.core.utils.UUIDs;
-import com.google.common.collect.ImmutableSet;
+import java.io.IOException;
+import java.util.HashMap;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+/**
+ * Live test for Cassandra testing.
+ *
+ * This can be converted to IntegrationTest once cassandra-unit tests can be executed in parallel and
+ * multiple test servers started as part of test suite.
+ *
+ * Open cassandra-unit issue for parallel execution: https://github.com/jsevellec/cassandra-unit/issues/155
+ */
 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration(classes = CassandraConfig.class)
-public class BookRepositoryIntegrationTest {
-    private static final Log LOGGER = LogFactory.getLog(BookRepositoryIntegrationTest.class);
+public class BookRepositoryLiveTest {
+    private static final Log LOGGER = LogFactory.getLog(BookRepositoryLiveTest.class);
 
     public static final String KEYSPACE_CREATION_QUERY = "CREATE KEYSPACE IF NOT EXISTS testKeySpace WITH replication = { 'class': 'SimpleStrategy', 'replication_factor': '3' };";
 
@@ -47,8 +54,6 @@ public class BookRepositoryIntegrationTest {
     @Autowired
     private CassandraAdminOperations adminTemplate;
 
-    //
-
     @BeforeClass
     public static void startCassandraEmbedded() throws InterruptedException, TTransportException, ConfigurationException, IOException {
         EmbeddedCassandraServerHelper.startEmbeddedCassandra();
@@ -62,8 +67,8 @@ public class BookRepositoryIntegrationTest {
     }
 
     @Before
-    public void createTable() throws InterruptedException, TTransportException, ConfigurationException, IOException {
-        adminTemplate.createTable(true, CqlIdentifier.cqlId(DATA_TABLE_NAME), Book.class, new HashMap<String, Object>());
+    public void createTable() {
+        adminTemplate.createTable(true, CqlIdentifier.cqlId(DATA_TABLE_NAME), Book.class, new HashMap<>());
     }
 
     @Test