Merge branch 'eugenp:master' into master

algorithms-miscellaneous-6/src/main/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingDeque.java

@@ -31,6 +31,6 @@ public class BalancedBracketsUsingDeque {
             }
         }
 
-        return true;
+        return deque.isEmpty();
     }
 }

algorithms-miscellaneous-6/src/test/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingDequeUnitTest.java

@@ -49,6 +49,12 @@ public class BalancedBracketsUsingDequeUnitTest {
         assertThat(result).isFalse();
     }
 
+    @Test
+    public void givenAnotherEvenLengthUnbalancedString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{{}(");
+        assertThat(result).isFalse();
+    }
+
     @Test
     public void givenEvenLengthBalancedString_whenCheckingForBalance_shouldReturnTrue() {
         boolean result = balancedBracketsUsingDeque.isBalanced("{[()]}");

algorithms-miscellaneous-6/src/test/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingStringUnitTest.java

@@ -49,6 +49,12 @@ public class BalancedBracketsUsingStringUnitTest {
         assertThat(result).isFalse();
     }
 
+    @Test
+    public void givenAnotherEvenLengthUnbalancedString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingString.isBalanced("{{}(");
+        assertThat(result).isFalse();
+    }
+
     @Test
     public void givenEvenLengthBalancedString_whenCheckingForBalance_shouldReturnTrue() {
         boolean result = balancedBracketsUsingString.isBalanced("{[()]}");

apache-spark/data/customerData.csv

@@ -0,0 +1,9 @@
+id,zoneId,FIRST_NAME,MIDDLE_NAME,LAST_NAME,CITY,gender,transaction_date,transaction_amount
+1,EU11,Ana1,A,MN, London,Female,1/2/2018,5200
+2,EU12,Ana2,A,MN, London,Female,29/3/2018,1000
+3,EU13,Jack1,Josh,MN, London,Male,19/6/2018,9600
+4,EU14,Jack2,Josh,MN, London,Male,9/9/2018,1000
+5,EU15,Nick1,H,Dee,London,Male,9/6/2021,3000
+6,EU16,Nick2,H,Dee,London,Male,27/9/2021,500
+7,EU17,Nick3,H,Dee,London,Male,8/12/2021,500
+8,EU18,Sara1,H,Dee,London,Female,7/4/2021,2000

apache-spark/data/customerData.json

@@ -0,0 +1,114 @@
+[
+  {
+    "zoneId": "LONDON",
+    "customerId": 1,
+    "gender": "Female",
+    "name": "jane austin",
+    "contact": {
+      "street_Address": "XYZ Road",
+      "address2": "house 47",
+      "zipcode": "MK1110",
+      "county": "DCounty",
+      "phone_number": "(919) 403-0025",
+      "customer_city": "CityA"
+    },
+    "transaction_date": "2021-02-05",
+    "transaction_amount": 15000
+  },
+  {
+    "zoneId": "LONDON",
+    "customerId": 2,
+    "gender": "Male",
+    "name": "Jack Trevor",
+    "contact": {
+      "street_Address": " kingfisher road",
+      "address2": "SUITE 110",
+      "zipcode": "HM1190",
+      "county": "CCounty",
+      "phone_number": "(919) 403-0025",
+      "customer_city": "CityB"
+    },
+    "transaction_date": "2021-02-05",
+    "transaction_amount": 12000
+  },
+  {
+    "zoneId": "LONDON",
+    "customerId": 11,
+    "gender": "Female",
+    "name": "jane1 austin",
+    "contact": {
+      "street_Address": "B Road",
+      "address2": "house 47",
+      "zipcode": "MK1110",
+      "county": "BCounty",
+      "phone_number": "(919) 403-0025",
+      "customer_city": "CityA"
+    },
+    "transaction_date": "2021-02-05",
+    "transaction_amount": 1000
+  },
+  {
+    "zoneId": "LONDON",
+    "customerId": 21,
+    "gender": "Male",
+    "name": "Jack1 Trevor",
+    "contact": {
+      "street_Address": " A road",
+      "address2": "SUITE 777",
+      "zipcode": "AZ890",
+      "county": "ACounty",
+      "phone_number": "(919) 403-0025",
+      "customer_city": "CityB"
+    },
+    "transaction_date": "2021-02-05",
+    "transaction_amount": 1000
+  },
+  {
+    "zoneId": "Wales",
+    "customerId": 3,
+    "gender": "Male",
+    "name": "John Jack",
+    "contact": {
+      "street_Address": "sunny croft",
+      "address2": "SUITE 1",
+      "zipcode": "SN1030",
+      "county": "bucks",
+      "phone_number": "(919) 403-0025",
+      "customer_city": "Cardiff"
+    },
+    "transaction_date": "2018-02-05",
+    "transaction_amount": 5000
+  },
+  {
+    "zoneId": "LONDON",
+    "customerId": 4,
+    "gender": "Male",
+    "name": "Jack Trevor",
+    "contact": {
+      "street_Address": " kingfisher road",
+      "address2": "SUITE 110",
+      "zipcode": "HM1190",
+      "county": "Hampshire",
+      "phone_number": "(919) 403-0025",
+      "customer_city": "CityB"
+    },
+    "transaction_date": "2021-02-05",
+    "transaction_amount": 500
+  },
+  {
+    "zoneId": "Wales",
+    "customerId": 5,
+    "gender": "Male",
+    "name": "John Jack",
+    "contact": {
+      "street_Address": "sunny croft",
+      "address2": "SUITE 1",
+      "zipcode": "SN1030",
+      "county": "ECounty",
+      "phone_number": "(919) 403-0025",
+      "customer_city": "Cardiff"
+    },
+    "transaction_date": "2018-01-25",
+    "transaction_amount": 500
+  }
+]

apache-spark/data/minCustomerData.json

@@ -0,0 +1,20 @@
+[
+  {
+    "id": "1",
+    "gender": "Female",
+    "name": "Jo",
+    "transaction_amount": 200
+  },
+  {
+    "id":"2",
+    "gender": "Male",
+    "name": "Mike",
+    "transaction_amount": 500
+  },
+  {
+    "id": "3",
+    "gender": "Male",
+    "name": "Dave",
+    "transaction_amount": 5000
+  }
+]

apache-spark/docker/docker-compose.yaml

@@ -0,0 +1,33 @@
+version: "3"
+
+services:
+    postgres:
+        image: postgres:12.3-alpine
+        restart: always
+        environment:
+            POSTGRES_PASSWORD: postgres
+            POSTGRES_USER: postgres
+        expose:
+            - 5432
+        ports:
+            - 5432:5432
+        command: -p 5432        
+        volumes:
+            - ./init.sql:/docker-entrypoint-initdb.d/init.sql
+#            - postgres:/var/lib/postgresql/data
+
+    pgadmin:
+        image: dpage/pgadmin4:4.23
+        environment:
+            PGADMIN_DEFAULT_EMAIL: admin@pgadmin.com
+            PGADMIN_DEFAULT_PASSWORD: password
+            PGADMIN_LISTEN_PORT: 80
+        ports:
+            - 15432:80
+        volumes:
+            - pgadmin:/var/lib/pgadmin
+        depends_on:
+            - postgres
+
+volumes:
+    pgadmin:

apache-spark/docker/init.sql

@@ -0,0 +1 @@
+CREATE DATABASE customerdb;

apache-spark/pom.xml

@@ -20,37 +20,31 @@
             <groupId>org.apache.spark</groupId>
             <artifactId>spark-core_2.11</artifactId>
             <version>${org.apache.spark.spark-core.version}</version>
-            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.spark</groupId>
             <artifactId>spark-sql_2.11</artifactId>
             <version>${org.apache.spark.spark-sql.version}</version>
-            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.spark</groupId>
             <artifactId>spark-graphx_2.11</artifactId>
             <version>${org.apache.spark.spark-graphx.version}</version>
-            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>graphframes</groupId>
             <artifactId>graphframes</artifactId>
             <version>${graphframes.version}</version>
-            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.spark</groupId>
             <artifactId>spark-streaming_2.11</artifactId>
             <version>${org.apache.spark.spark-streaming.version}</version>
-            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.spark</groupId>
             <artifactId>spark-mllib_2.11</artifactId>
             <version>${org.apache.spark.spark-mllib.version}</version>
-            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.spark</groupId>
@@ -67,6 +61,11 @@
             <artifactId>spark-cassandra-connector-java_2.11</artifactId>
             <version>${com.datastax.spark.spark-cassandra-connector-java.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.postgresql</groupId>
+            <artifactId>postgresql</artifactId>
+            <version>${postgres.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -108,6 +107,7 @@
         <org.apache.spark.spark-streaming-kafka.version>2.4.8</org.apache.spark.spark-streaming-kafka.version>
         <com.datastax.spark.spark-cassandra-connector.version>2.5.2</com.datastax.spark.spark-cassandra-connector.version>
         <com.datastax.spark.spark-cassandra-connector-java.version>1.6.0-M1</com.datastax.spark.spark-cassandra-connector-java.version>
+        <postgres.version>42.3.3</postgres.version>
     </properties>
 
 </project>

apache-spark/src/main/java/com/baeldung/dataframes/Customer.java

@@ -0,0 +1,52 @@
+package com.baeldung.dataframes;
+
+public class Customer {
+    String id;
+    String name;
+    String gender;
+    int transaction_amount;
+
+    public Customer() {
+
+    }
+
+    public Customer(String id, String name, String gender, int transaction_amount) {
+        this.id = id;
+        this.name = name;
+        this.gender = gender;
+        this.transaction_amount = transaction_amount;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getGender() {
+        return gender;
+    }
+
+    public void setGender(String gender) {
+        this.gender = gender;
+    }
+
+    public int getTransaction_amount() {
+        return transaction_amount;
+    }
+
+    public void setTransaction_amount(int transaction_amount) {
+        this.transaction_amount = transaction_amount;
+    }
+
+}

apache-spark/src/main/java/com/baeldung/dataframes/CustomerDataAggregationPipeline.java

@@ -0,0 +1,129 @@
+package com.baeldung.dataframes;
+
+import static org.apache.spark.sql.functions.col;
+import static org.apache.spark.sql.functions.column;
+import static org.apache.spark.sql.functions.concat;
+import static org.apache.spark.sql.functions.lit;
+
+import java.util.Properties;
+
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.SaveMode;
+import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.functions;
+
+public class CustomerDataAggregationPipeline {
+    private static final SparkSession SPARK_SESSION = SparkDriver.getSparkSession();
+
+    private final Properties dbProperties;
+
+    public CustomerDataAggregationPipeline(Properties properties) {
+        dbProperties = properties;
+    }
+
+    public static void main(String[] args) {
+        // replace with actual DB properties
+        Properties dbProps = new Properties();
+        dbProps.setProperty("connectionURL", "jdbc:postgresql://localhost:5432/customerdb");
+        dbProps.setProperty("driver", "org.postgresql.Driver");
+        dbProps.setProperty("user", "postgres");
+        dbProps.setProperty("password", "postgres");
+
+        new CustomerDataAggregationPipeline(dbProps).run();
+    }
+
+    public void run() {
+        Dataset<Row> ebayDFRaw = ingestCustomerDataFromEbay();
+        Dataset<Row> ebayDf = normalizeCustomerDataFromEbay(ebayDFRaw);
+
+        Dataset<Row> amazonDFRaw = ingestCustomerDataFromAmazon();
+        Dataset<Row> amazonDf = normalizeCustomerDataFromAmazon(amazonDFRaw);
+
+        Dataset<Row> combineDataframes = combineDataframes(ebayDf, amazonDf);
+
+        Dataset<Row> rowDataset = aggregateYearlySalesByGender(combineDataframes);
+
+        exportData(rowDataset);
+    }
+
+    private static Dataset<Row> ingestCustomerDataFromAmazon() {
+        return SPARK_SESSION.read()
+            .format("csv")
+            .option("header", "true")
+            .schema(SchemaFactory.customerSchema())
+            .option("dateFormat", "m/d/YYYY")
+            .load("data/customerData.csv");
+    }
+
+    private static Dataset<Row> ingestCustomerDataFromEbay() {
+        return SPARK_SESSION.read()
+            .format("org.apache.spark.sql.execution.datasources.json.JsonFileFormat")
+            .option("multiline", true)
+            .load("data/customerData.json");
+    }
+
+    private static Dataset<Row> combineDataframes(Dataset<Row> df1, Dataset<Row> df2) {
+        return df1.unionByName(df2);
+    }
+
+    private static Dataset<Row> normalizeCustomerDataFromEbay(Dataset<Row> rawDataset) {
+        Dataset<Row> transformedDF = rawDataset.withColumn("id", concat(rawDataset.col("zoneId"), lit("-"), rawDataset.col("customerId")))
+            .drop(column("customerId"))
+            .withColumn("source", lit("ebay"))
+            .withColumn("city", rawDataset.col("contact.customer_city"))
+            .drop(column("contact"))
+            .drop(column("zoneId"))
+            .withColumn("year", functions.year(col("transaction_date")))
+            .drop("transaction_date")
+            .withColumn("firstName", functions.split(column("name"), " ")
+                .getItem(0))
+            .withColumn("lastName", functions.split(column("name"), " ")
+                .getItem(1))
+            .drop(column("name"));
+
+        print(transformedDF);
+        return transformedDF;
+    }
+
+    private static Dataset<Row> normalizeCustomerDataFromAmazon(Dataset<Row> rawDataset) {
+
+        Dataset<Row> transformedDF = rawDataset.withColumn("id", concat(rawDataset.col("zoneId"), lit("-"), rawDataset.col("id")))
+            .withColumn("source", lit("amazon"))
+            .withColumnRenamed("CITY", "city")
+            .withColumnRenamed("PHONE_NO", "contactNo")
+            .withColumnRenamed("POSTCODE", "postCode")
+            .withColumnRenamed("FIRST_NAME", "firstName")
+            .drop(column("MIDDLE_NAME"))
+            .drop(column("zoneId"))
+            .withColumnRenamed("LAST_NAME", "lastName")
+            .withColumn("year", functions.year(col("transaction_date")))
+            .drop("transaction_date");
+
+        print(transformedDF);
+        return transformedDF;
+    }
+
+    private static Dataset<Row> aggregateYearlySalesByGender(Dataset<Row> dataset) {
+
+        Dataset<Row> aggDF = dataset.groupBy(column("year"), column("source"), column("gender"))
+            .sum("transaction_amount")
+            .withColumnRenamed("sum(transaction_amount)", "annual_spending")
+            .orderBy(col("year").asc(), col("annual_spending").desc());
+
+        print(aggDF);
+        return aggDF;
+    }
+
+    private static void print(Dataset<Row> aggDs) {
+        aggDs.show();
+        aggDs.printSchema();
+    }
+
+    private void exportData(Dataset<Row> dataset) {
+        String connectionURL = dbProperties.getProperty("connectionURL");
+        dataset.write()
+            .mode(SaveMode.Overwrite)
+            .jdbc(connectionURL, "customer", dbProperties);
+    }
+}

apache-spark/src/main/java/com/baeldung/dataframes/CustomerToDataFrameConverterApp.java

@@ -0,0 +1,46 @@
+package com.baeldung.dataframes;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Row;
+
+public class CustomerToDataFrameConverterApp {
+
+    private static final List<Customer>  CUSTOMERS = Arrays.asList(
+        aCustomerWith("01", "jo", "Female", 2000),
+        aCustomerWith("02", "jack", "Male", 1200)
+    );
+
+    public static void main(String[] args) {
+        Dataset<Row> dataFrame = convertAfterMappingRows(CUSTOMERS);
+        print(dataFrame);
+        Dataset<Row> customerDF = convertToDataFrameWithNoChange();
+        print(customerDF);
+    }
+
+    public static Dataset<Row> convertToDataFrameWithNoChange() {
+       return SparkDriver.getSparkSession().createDataFrame(CUSTOMERS, Customer.class);
+    }
+
+    public static Dataset<Row> convertAfterMappingRows(List<Customer> customer) {
+        List<Row> rows = customer.stream()
+            .map(c -> new CustomerToRowMapper().call(c))
+            .collect(Collectors.toList());
+
+        return SparkDriver.getSparkSession()
+            .createDataFrame(rows, SchemaFactory.minimumCustomerDataSchema());
+    }
+
+    private static Customer aCustomerWith(String id, String name, String gender, int amount) {
+        return new Customer(id, name, gender, amount);
+    }
+
+    private static void print(Dataset<Row> dataFrame) {
+        dataFrame.printSchema();
+        dataFrame.show();
+    }
+
+}

apache-spark/src/main/java/com/baeldung/dataframes/CustomerToRowMapper.java

@@ -0,0 +1,18 @@
+package com.baeldung.dataframes;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.spark.api.java.function.MapFunction;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.RowFactory;
+
+public class CustomerToRowMapper implements MapFunction<Customer, Row> {
+
+    @Override
+    public Row call(Customer customer) {
+        Row row = RowFactory.create(
+            customer.getId(), customer.getName().toUpperCase(),
+            StringUtils.substring(customer.getGender(),0, 1),
+            customer.getTransaction_amount());
+        return row;
+    }
+}

apache-spark/src/main/java/com/baeldung/dataframes/DataFrameToCustomerConverterApp.java

@@ -0,0 +1,21 @@
+package com.baeldung.dataframes;
+
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Encoders;
+import org.apache.spark.sql.Row;
+
+public class DataFrameToCustomerConverterApp {
+
+    public static void main(String[] args) {
+        Dataset<Row> df = SparkDriver.getSparkSession()
+            .read()
+            .format("org.apache.spark.sql.execution.datasources.json.JsonFileFormat")
+            .option("multiline", true)
+            .load("data/minCustomerData.json");
+        df.show();
+        df.printSchema();
+        Dataset<Customer> customerDS = df.map(new RowToCustomerMapper(), Encoders.bean(Customer. class));
+        customerDS.show();
+        customerDS.printSchema();
+    }
+}

apache-spark/src/main/java/com/baeldung/dataframes/DataSetToDataFrameConverterApp.java

@@ -0,0 +1,57 @@
+package com.baeldung.dataframes;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Encoders;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.SparkSession;
+
+public class DataSetToDataFrameConverterApp {
+
+    private static final SparkSession SPARK_SESSION = SparkDriver.getSparkSession();
+
+    public static void main(String[] args) {
+
+        Dataset<Customer> customerDataset = convertToDataSetFromPOJO();
+        Dataset<Row> customerDataFrame = customerDataset.toDF();
+        print(customerDataFrame);
+
+        List<String> names = getNames();
+        Dataset<String> namesDataset = convertToDataSetFromStrings(names);
+        Dataset<Row> namesDataFrame = namesDataset.toDF();
+        print(namesDataFrame);
+    }
+
+    private static Dataset<String> convertToDataSetFromStrings(List<String> names) {
+        return SPARK_SESSION.createDataset(names, Encoders.STRING());
+    }
+
+    private static Dataset<Customer> convertToDataSetFromPOJO() {
+        return SPARK_SESSION.createDataset(CUSTOMERS, Encoders.bean(Customer.class));
+    }
+
+    private static final List<Customer> CUSTOMERS = Arrays.asList(
+        aCustomerWith("01", "jo", "Female", 2000),
+        aCustomerWith("02", "jack", "Female", 1200),
+        aCustomerWith("03", "ash", "male", 2000),
+        aCustomerWith("04", "emma", "Female", 2000)
+    );
+
+    private static List<String> getNames() {
+        return CUSTOMERS.stream()
+            .map(Customer::getName)
+            .collect(Collectors.toList());
+    }
+
+    private static void print(Dataset<Row> df) {
+        df.show();
+        df.printSchema();
+    }
+
+    private static Customer aCustomerWith(String id, String name, String gender, int amount) {
+        return new Customer(id, name, gender, amount);
+    }
+}

apache-spark/src/main/java/com/baeldung/dataframes/RowToCustomerMapper.java

@@ -0,0 +1,19 @@
+package com.baeldung.dataframes;
+
+import org.apache.spark.api.java.function.MapFunction;
+import org.apache.spark.sql.Row;
+
+class RowToCustomerMapper implements MapFunction<Row, Customer> {
+
+    @Override
+    public Customer call(Row row) {
+
+        Customer customer = new Customer();
+        customer.setId(row.getAs("id"));
+        customer.setName(row.getAs("name"));
+        customer.setGender(row.getAs("gender"));
+        customer.setTransaction_amount(Math.toIntExact(row.getAs("transaction_amount")));
+
+        return customer;
+    }
+}

apache-spark/src/main/java/com/baeldung/dataframes/SchemaFactory.java

@@ -0,0 +1,31 @@
+package com.baeldung.dataframes;
+
+import org.apache.spark.sql.types.DataTypes;
+import org.apache.spark.sql.types.StructField;
+import org.apache.spark.sql.types.StructType;
+
+public class SchemaFactory {
+
+    public static StructType customerSchema() {
+        return DataTypes.createStructType(
+            new StructField[] { DataTypes.createStructField("id", DataTypes.IntegerType, false),
+                DataTypes.createStructField("zoneId", DataTypes.StringType, false),
+                DataTypes.createStructField("FIRST_NAME", DataTypes.StringType, false),
+                DataTypes.createStructField("MIDDLE_NAME", DataTypes.StringType, false),
+                DataTypes.createStructField("LAST_NAME", DataTypes.StringType, false),
+                DataTypes.createStructField("CITY", DataTypes.StringType, false),
+                DataTypes.createStructField("gender", DataTypes.StringType, false),
+                DataTypes.createStructField("transaction_date", DataTypes.DateType, false),
+                DataTypes.createStructField("transaction_amount", DataTypes.IntegerType, false)
+            });
+    }
+
+    public static StructType minimumCustomerDataSchema() {
+        return DataTypes.createStructType(new StructField[] {
+            DataTypes.createStructField("id", DataTypes.StringType, true),
+            DataTypes.createStructField("name", DataTypes.StringType, true),
+            DataTypes.createStructField("gender", DataTypes.StringType, true),
+            DataTypes.createStructField("transaction_amount", DataTypes.IntegerType, true)
+        });
+    }
+}

apache-spark/src/main/java/com/baeldung/dataframes/SparkDriver.java

@@ -0,0 +1,16 @@
+package com.baeldung.dataframes;
+
+import java.io.Serializable;
+
+import org.apache.spark.sql.SparkSession;
+
+public class SparkDriver implements Serializable {
+
+    public static SparkSession getSparkSession() {
+        return SparkSession.builder()
+            .appName("Customer Aggregation pipeline")
+            .master("local")
+            .getOrCreate();
+
+    }
+}

apache-spark/src/test/java/com/baeldung/dataframes/CustomerDataAggregationPipelineLiveTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.dataframes;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.Properties;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class CustomerDataAggregationPipelineLiveTest {
+
+    private static Connection conn;
+
+    @BeforeAll
+    static void beforeAll() throws SQLException {
+        DriverManager.registerDriver(new org.postgresql.Driver());
+        String dbURL1 = "jdbc:postgresql://localhost:5432/customerdb";
+        conn = DriverManager.getConnection(dbURL1, "postgres", "postgres");
+
+        String sql = "drop table if exists customer";
+
+        PreparedStatement statement = conn.prepareStatement(sql);
+        statement.executeUpdate();
+    }
+
+    @Test
+    void givenCSVAndJSON_whenRun_thenStoresAggregatedDataFrameInDB() throws Exception {
+        Properties dbProps = new Properties();
+        dbProps.setProperty("connectionURL", "jdbc:postgresql://localhost:5432/customerdb");
+        dbProps.setProperty("driver", "org.postgresql.Driver");
+        dbProps.setProperty("user", "postgres");
+        dbProps.setProperty("password", "postgres");
+
+        CustomerDataAggregationPipeline pipeline = new CustomerDataAggregationPipeline(dbProps);
+        pipeline.run();
+
+        String allCustomersSql = "Select count(*) from customer";
+
+        Statement statement = conn.createStatement();
+        ResultSet resultSet = statement.executeQuery(allCustomersSql);
+        resultSet.next();
+        int count = resultSet.getInt(1);
+        assertEquals(7, count);
+    }
+
+}

apache-spark/src/test/java/com/baeldung/dataframes/CustomerToDataFrameConverterAppUnitTest.java

@@ -0,0 +1,62 @@
+package com.baeldung.dataframes;
+
+import static com.baeldung.dataframes.CustomerToDataFrameConverterApp.convertAfterMappingRows;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Row;
+import org.junit.jupiter.api.Test;
+
+class CustomerToDataFrameConverterAppUnitTest {
+
+    @Test
+    void givenCustomers_whenConvertAfterMappingRows_thenConvertsToDataSet() {
+
+       List<Customer> customers = Arrays.asList(
+            new Customer("01", "jo", "Female", 2000),
+            new Customer("02", "jack", "Male", 1200)
+       );
+
+        Dataset<Row> customerDF = convertAfterMappingRows(customers);
+        List<Row> rows = customerDF.collectAsList();
+        Row row1 = rows.get(0);
+        Row row2 = rows.get(1);
+
+        assertEquals("01", row1.get(0));
+        assertEquals( "JO", row1.get(1));
+        assertEquals( "F", row1.get(2));
+        assertEquals( 2000, row1.get(3));
+
+        assertEquals("02", row2.get(0));
+        assertEquals( "JACK", row2.get(1));
+        assertEquals( "M", row2.get(2));
+        assertEquals( 1200, row2.get(3));
+    }
+
+    @Test
+    void givenCustomers_whenConvertWithNoChange_thenConvertsToDataSet() {
+
+        List<Customer> customers = Arrays.asList(
+            new Customer("01", "jo", "Female", 2000),
+            new Customer("02", "jack", "Male", 1200)
+        );
+
+        Dataset<Row> customerDF = CustomerToDataFrameConverterApp.convertToDataFrameWithNoChange();
+        List<Row> rows = customerDF.collectAsList();
+        Row row1 = rows.get(0);
+        Row row2 = rows.get(1);
+
+        assertEquals("01", row1.getAs("id"));
+        assertEquals( "jo", row1.getAs("name"));
+        assertEquals( "Female", row1.getAs("gender"));
+        assertEquals( 2000, (int)row1.getAs("transaction_amount"));
+
+        assertEquals("02", row2.getAs("id"));
+        assertEquals( "jack", row2.getAs("name"));
+        assertEquals( "Male", row2.getAs("gender"));
+        assertEquals( 1200, (int)row2.getAs("transaction_amount"));
+    }
+}

core-java-modules/README.md

@@ -4,6 +4,6 @@ This module contains modules about core Java
 
 ## Relevant articles:
 
-- [Multi-Module Maven Application with Java Modules](https://www.baeldung.com/maven-multi-module-project-java-jpms)
 - [Understanding the NumberFormatException in Java](https://www.baeldung.com/java-number-format-exception)
-- [Will an Error Be Caught by Catch Block in Java?](https://www.baeldung.com/java-error-catch)
+
+

core-java-modules/core-java-concurrency-advanced-4/src/main/java/com/baeldung/setvslazyset/Application.java

@@ -0,0 +1,35 @@
+package com.baeldung.setvslazyset;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class Application {
+
+    AtomicInteger atomic = new AtomicInteger(0);
+
+    public static void main(String[] args) {
+        Application app = new Application();
+        new Thread(() -> {
+            for (int i = 0; i < 10; i++) {
+                //app.atomic.set(i);
+                app.atomic.lazySet(i);
+                System.out.println("Set: " + i);
+                try {
+                    Thread.sleep(100);
+                } catch (InterruptedException e) {}
+            }
+        }).start();
+
+        new Thread(() -> {
+            for (int i = 0; i < 10; i++) {
+                synchronized (app.atomic) {
+                    int counter = app.atomic.get();
+                    System.out.println("Get: " + counter);
+                }
+                try {
+                    Thread.sleep(100);
+                } catch (InterruptedException e) {}
+            }
+        }).start();
+    }
+
+}

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

@@ -13,4 +13,5 @@ This module contains articles about core java exceptions
 - [The StackOverflowError in Java](https://www.baeldung.com/java-stack-overflow-error)
 - [Checked and Unchecked Exceptions in Java](https://www.baeldung.com/java-checked-unchecked-exceptions)
 - [Common Java Exceptions](https://www.baeldung.com/java-common-exceptions)
+- [Will an Error Be Caught by Catch Block in Java?](https://www.baeldung.com/java-error-catch)
 - [[Next -->]](/core-java-modules/core-java-exceptions-2)

core-java-modules/core-java-io-4/README.md

@@ -9,4 +9,5 @@ This module contains articles about core Java input and output (IO)
 - [SequenceInputStream Class in Java](https://www.baeldung.com/java-sequenceinputstream)
 - [Read a File Into a Map in Java](https://www.baeldung.com/java-read-file-into-map)
 - [Read User Input Until a Condition is Met](https://www.baeldung.com/java-read-input-until-condition)
+- [Java Scanner.skip method with examples](https://www.baeldung.com/java-scanner-skip)
 - [[<-- Prev]](/core-java-modules/core-java-io-3)

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

@@ -7,3 +7,4 @@
 - [Exceptions in Java 8 Lambda Expressions](http://www.baeldung.com/java-lambda-exceptions)
 - [Method References in Java](https://www.baeldung.com/java-method-references)
 - [The Double Colon Operator in Java 8](https://www.baeldung.com/java-8-double-colon-operator)
+- [Serialize a Lambda in Java](https://www.baeldung.com/java-serialize-lambda)

core-java-modules/core-java-lang-5/README.md

@@ -0,0 +1,5 @@
+## Core Java Lang (Part 5)
+
+This module contains articles about core features in the Java language
+
+## TODO ##

core-java-modules/core-java-lang-5/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-lang-5</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-lang-5</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-lang-5</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+</project>

core-java-modules/core-java-lang-5/src/test/java/com/baeldung/nullchecks/NullChecksUnitTest.java

@@ -0,0 +1,125 @@
+package com.baeldung.nullchecks;
+
+import org.junit.Test;
+
+import java.util.Objects;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class NullChecksUnitTest {
+
+    @Test
+    public void whenReferenceEqualityOnPrimitives_thenCompareValues() {
+        int a = 10;
+        int b = 15;
+        int c = 10;
+        int d = a;
+
+        // different values check
+        assertFalse(a == b);
+
+        // same values check
+        assertTrue(a == c);
+
+        // same references check
+        assertTrue(a == d);
+    }
+
+    @Test
+    public void whenReferenceEqualityOnObjects_thenCompareReferences() {
+        Person a = new Person("Bob", 20);
+        Person b = new Person("Mike", 40);
+        Person c = new Person("Bob", 20);
+        Person d = a;
+        Person e = null;
+
+        // different values check
+        assertFalse(a == b);
+
+        // same values check
+        assertFalse(a == c);
+
+        // same references check
+        assertTrue(a == d);
+
+        // same references check - for nulls
+        assertTrue(e == null);
+    }
+
+    @Test
+    public void whenValueEqualityOnPrimitives_thenCompareValues() {
+        int a = 10;
+        Integer b = a;
+
+        assertTrue(b.equals(10));
+    }
+
+    @Test
+    public void whenValueEqualityOnObjects_thenCompareValues() {
+        Person a = new Person("Bob", 20);
+        Person b = new Person("Mike", 40);
+        Person c = new Person("Bob", 20);
+        Person d = a;
+        Person e = null;
+
+        // different values check
+        assertFalse(a.equals(b));
+
+        // same values check
+        assertTrue(a.equals(c));
+
+        // same references check
+        assertTrue(a.equals(d));
+
+        // null checks
+        assertFalse(a.equals(e));
+        assertThrows(NullPointerException.class, () -> e.equals(a));
+
+        // null checks fixed
+        assertFalse(e != null && e.equals(a));
+
+        // using Objects.equals
+        assertFalse(Objects.equals(e, a));
+        assertTrue(Objects.equals(null, e));
+
+    }
+
+    private class Person {
+        private String name;
+        private int age;
+
+        public Person(String name, int age) {
+            this.name = name;
+            this.age = age;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public int getAge() {
+            return age;
+        }
+
+        public void setAge(int age) {
+            this.age = age;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            Person person = (Person) o;
+            return age == person.age && Objects.equals(name, person.name);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(name, age);
+        }
+    }
+}

core-java-modules/java-collections-conversions-2/pom.xml

@@ -9,10 +9,9 @@
     <packaging>jar</packaging>
 
     <parent>
-        <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
     </parent>
 
     <dependencies>

core-java-modules/java-collections-conversions/pom.xml

@@ -9,10 +9,9 @@
     <packaging>jar</packaging>
 
     <parent>
-        <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
     </parent>
 
     <dependencies>

core-java-modules/java-collections-maps-3/pom.xml

@@ -9,10 +9,9 @@
     <packaging>jar</packaging>
 
     <parent>
-        <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
     </parent>
 
     <dependencies>

core-java-modules/pom.xml

@@ -73,6 +73,7 @@
         <module>core-java-lang-2</module>
         <module>core-java-lang-3</module>
         <module>core-java-lang-4</module>
+        <module>core-java-lang-5</module>
         <module>core-java-lang-math</module>
         <module>core-java-lang-math-2</module>
         <module>core-java-lang-math-3</module>
@@ -117,6 +118,9 @@
         <module>core-java-regex</module>
         <module>core-java-regex-2</module>
         <module>core-java-uuid</module>
+        <module>java-collections-conversions</module>
+        <module>java-collections-conversions-2</module>
+        <module>java-collections-maps-3</module>
         <module>pre-jpms</module>
     </modules>
 

docker/docker-push-to-private-repo/.gitignore

@@ -0,0 +1,33 @@
+HELP.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

docker/docker-push-to-private-repo/Dockerfile

@@ -0,0 +1,4 @@
+FROM openjdk:11
+ARG JAR_FILE=target/*.jar
+COPY ${JAR_FILE} app.jar
+ENTRYPOINT ["java","-jar","/app.jar"]

docker/docker-push-to-private-repo/README.md

@@ -0,0 +1 @@
+### Relevant Articles:

docker/docker-push-to-private-repo/pom.xml

@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>com.baeldung.docker</groupId>
+        <artifactId>docker</artifactId>
+        <version>0.0.1</version>
+    </parent>
+    <artifactId>push-to-private-repo</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>push-to-private-repo</name>
+    <description>Example application to showcase how to push a docker image to a private repository</description>
+    <properties>
+        <java.version>11</java.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

docker/docker-push-to-private-repo/src/main/java/com/baeldung/docker/push/HelloWorldController.java

@@ -0,0 +1,12 @@
+package com.baeldung.docker.push;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class HelloWorldController {
+    @GetMapping("/helloworld")
+    String helloWorld() {
+        return "Hello World!";
+    }
+}

docker/docker-push-to-private-repo/src/main/java/com/baeldung/docker/push/PushToPrivateRepoApplication.java

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

docker/docker-push-to-private-repo/src/main/resources/application.properties

@@ -0,0 +1 @@
+

docker/pom.xml

@@ -28,6 +28,7 @@
         <module>docker-sample-app</module>
         <module>docker-caching/single-module-caching</module>
         <module>docker-caching/multi-module-caching</module>
+        <module>docker-push-to-private-repo</module>
     </modules>
 
 </project>

graphql/graphql-error-handling/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Error Handling in GraphQL With Spring Boot](https://www.baeldung.com/spring-graphql-error-handling)

java-numbers-4/README.md

@@ -7,3 +7,4 @@
 - [Automorphic Numbers in Java](https://www.baeldung.com/java-automorphic-numbers)
 - [Convert Byte Size Into a Human-Readable Format in Java](https://www.baeldung.com/java-human-readable-byte-size)
 - [Convert boolean to int in Java](https://www.baeldung.com/java-boolean-to-int)
+- [Generate a Random Value From an Enum](https://www.baeldung.com/java-enum-random-value)

json-2/README.md

@@ -9,4 +9,5 @@ This module contains articles about JSON.
 - [Hypermedia Serialization With JSON-LD](https://www.baeldung.com/json-linked-data)
 - [Generate a Java Class From JSON](https://www.baeldung.com/java-generate-class-from-json)
 - [A Guide to FastJson](https://www.baeldung.com/fastjson)
+- [Check Whether a String is Valid JSON in Java](https://www.baeldung.com/java-validate-json-string)
 - More Articles: [[<-- prev]](/json)

maven-modules/maven-parent-pom-resolution/README.md

@@ -1,3 +1,4 @@
 ### Relevant Articles:
 
 - [Understanding Maven’s “relativePath” Tag for a Parent POM](https://www.baeldung.com/maven-relativepath)
+- [How to Disable a Maven Plugin Defined in a Parent POM](https://www.baeldung.com/maven-disable-parent-pom-plugin)

persistence-modules/deltaspike/pom.xml

@@ -278,13 +278,6 @@
         </license>
     </licenses>
 
-    <repositories>
-        <repository>
-            <id>redhat-repository-techpreview</id>
-            <url>https://maven.repository.redhat.com/techpreview/all/</url>
-        </repository>
-    </repositories>
-
     <properties>
         <querydsl.version>3.7.4</querydsl.version>
         <deltaspike.version>1.8.2</deltaspike.version>
@@ -296,7 +289,7 @@
         <!-- other plugin versions -->
         <war.plugin.version>2.6</war.plugin.version>
         <apt-maven-plugin.version>1.1.3</apt-maven-plugin.version>
-        <jandex.version>1.2.5.Final-redhat-1</jandex.version>
+        <jandex.version>1.2.4.Final</jandex.version>
     </properties>
 
 </project>

persistence-modules/hibernate-annotations/pom.xml

@@ -85,7 +85,7 @@
         <hibernate-core.version>5.6.7.Final</hibernate-core.version>
         <maven.deploy.skip>true</maven.deploy.skip>
         <spring-boot.version>2.1.7.RELEASE</spring-boot.version>
-        <h2.version>1.4.200</h2.version>
+        <h2.version>2.1.212</h2.version>
         <tomcat-dbcp.version>9.0.0.M26</tomcat-dbcp.version>
         <hsqldb.version>2.3.4</hsqldb.version>
     </properties>

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/HibernateUtil.java

@@ -1,10 +1,5 @@
 package com.baeldung.hibernate;
 
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.net.URL;
-import java.util.Properties;
-
 import org.apache.commons.lang3.StringUtils;
 import org.hibernate.SessionFactory;
 import org.hibernate.boot.Metadata;
@@ -12,62 +7,58 @@ import org.hibernate.boot.MetadataSources;
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
 import org.hibernate.service.ServiceRegistry;
 
-import com.baeldung.hibernate.joincolumn.Email;
-import com.baeldung.hibernate.joincolumn.Office;
-import com.baeldung.hibernate.joincolumn.OfficeAddress;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.net.URL;
+import java.util.List;
+import java.util.Properties;
+
+import static java.util.Objects.requireNonNull;
 
 public class HibernateUtil {
-    private static String PROPERTY_FILE_NAME;
 
-    public static SessionFactory getSessionFactory() throws IOException {
-        return getSessionFactory(null);
+    public static SessionFactory getSessionFactory(String propertyFileName, List<Class<?>> classes) throws IOException {
+        ServiceRegistry serviceRegistry = configureServiceRegistry(propertyFileName);
+        return makeSessionFactory(serviceRegistry, classes);
     }
 
-    public static SessionFactory getSessionFactory(String propertyFileName) throws IOException {
-        PROPERTY_FILE_NAME = propertyFileName;
-        ServiceRegistry serviceRegistry = configureServiceRegistry();
-        return makeSessionFactory(serviceRegistry);
-    }
-
-    public static SessionFactory getSessionFactoryByProperties(Properties properties) throws IOException {
-        ServiceRegistry serviceRegistry = configureServiceRegistry(properties);
-        return makeSessionFactory(serviceRegistry);
-    }
-
-    private static SessionFactory makeSessionFactory(ServiceRegistry serviceRegistry) {
+    private static SessionFactory makeSessionFactory(ServiceRegistry serviceRegistry, List<Class<?>> classes) {
         MetadataSources metadataSources = new MetadataSources(serviceRegistry);
-
-        metadataSources.addPackage("com.baeldung.hibernate.pojo");
-        metadataSources.addAnnotatedClass(com.baeldung.hibernate.joincolumn.OfficialEmployee.class);
-        metadataSources.addAnnotatedClass(Email.class);
-        metadataSources.addAnnotatedClass(Office.class);
-        metadataSources.addAnnotatedClass(OfficeAddress.class);
-
-        Metadata metadata = metadataSources.getMetadataBuilder()
-                .build();
-
-        return metadata.getSessionFactoryBuilder()
-                .build();
-
+        for (Class<?> clazz: classes) {
+            metadataSources = metadataSources.addAnnotatedClass(clazz);
         }
 
-    private static ServiceRegistry configureServiceRegistry() throws IOException {
-        return configureServiceRegistry(getProperties());
+        Metadata metadata = metadataSources
+          .getMetadataBuilder()
+          .build();
+
+        return metadata.getSessionFactoryBuilder().build();
     }
 
-    private static ServiceRegistry configureServiceRegistry(Properties properties) throws IOException {
+    private static ServiceRegistry configureServiceRegistry(String propertyFileName) throws IOException {
+        return configureServiceRegistry(getProperties(propertyFileName));
+    }
+
+    private static ServiceRegistry configureServiceRegistry(Properties properties) {
         return new StandardServiceRegistryBuilder().applySettings(properties)
                 .build();
     }
 
-    public static Properties getProperties() throws IOException {
+    public static Properties getProperties(String propertyFileName) throws IOException {
         Properties properties = new Properties();
-        URL propertiesURL = Thread.currentThread()
-          .getContextClassLoader()
-          .getResource(StringUtils.defaultString(PROPERTY_FILE_NAME, "hibernate.properties"));
-        try (FileInputStream inputStream = new FileInputStream(propertiesURL.getFile())) {
+
+        String file = getResourceURL(propertyFileName).getFile();
+
+        try (FileInputStream inputStream = new FileInputStream(file)) {
             properties.load(inputStream);
         }
+
         return properties;
     }
+
+    private static URL getResourceURL(String propertyFileName) {
+        return requireNonNull(Thread.currentThread()
+          .getContextClassLoader()
+          .getResource(StringUtils.defaultString(propertyFileName, "hibernate.properties")));
+    }
 }

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/customtypes/OfficeEmployee.java

@@ -1,6 +1,5 @@
 package com.baeldung.hibernate.customtypes;
 
-import com.baeldung.hibernate.pojo.Phone;
 import org.hibernate.annotations.Columns;
 import org.hibernate.annotations.Parameter;
 import org.hibernate.annotations.Type;

persistence-modules/hibernate-annotations/src/main/java/com/baeldung/hibernate/oneToMany/config/HibernateAnnotationUtil.java

@@ -7,29 +7,30 @@ import com.baeldung.hibernate.oneToMany.model.ItemOIO;
 import org.hibernate.SessionFactory;
 import org.hibernate.boot.Metadata;
 import org.hibernate.boot.MetadataSources;
-import org.hibernate.boot.model.naming.ImplicitNamingStrategyJpaCompliantImpl;
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.cfg.Environment;
 import org.hibernate.service.ServiceRegistry;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+
+import java.util.HashMap;
+import java.util.Map;
 
 public class HibernateAnnotationUtil {
 
-    private static final Logger LOGGER = LoggerFactory.getLogger(HibernateAnnotationUtil.class);
+    private static final SessionFactory SESSION_FACTORY = buildSessionFactory();
 
-    private static SessionFactory sessionFactory;
+    /**
+     * Utility class
+     */
+    private HibernateAnnotationUtil() {
+    }
 
     public static SessionFactory getSessionFactory() {
-        if (sessionFactory == null) {
-            sessionFactory = buildSessionFactory();
-        }
-        return sessionFactory;
+        return SESSION_FACTORY;
     }
 
     private static SessionFactory buildSessionFactory() {
-        try {
         ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
-              .configure("hibernate-annotation.cfg.xml")
+          .applySettings(dbSettings())
           .build();
 
         Metadata metadata = new MetadataSources(serviceRegistry)
@@ -37,15 +38,20 @@ public class HibernateAnnotationUtil {
           .addAnnotatedClass(CartOIO.class)
           .addAnnotatedClass(Item.class)
           .addAnnotatedClass(ItemOIO.class)
-              .getMetadataBuilder()
-              .applyImplicitNamingStrategy(ImplicitNamingStrategyJpaCompliantImpl.INSTANCE)
-              .build();
+          .buildMetadata();
 
-            return metadata.getSessionFactoryBuilder().build();
+        return metadata.buildSessionFactory();
+    }
 
-        } catch (Throwable ex) {
-            LOGGER.error("Initial SessionFactory creation failed.", ex);
-            throw new ExceptionInInitializerError(ex);
-        }
+    private static Map<String, String> dbSettings() {
+        Map<String, String> dbSettings = new HashMap<>();
+        dbSettings.put(Environment.URL, "jdbc:h2:mem:spring_hibernate_one_to_many");
+        dbSettings.put(Environment.USER, "sa");
+        dbSettings.put(Environment.PASS, "");
+        dbSettings.put(Environment.DRIVER, "org.h2.Driver");
+        dbSettings.put(Environment.CURRENT_SESSION_CONTEXT_CLASS, "thread");
+        dbSettings.put(Environment.SHOW_SQL, "true");
+        dbSettings.put(Environment.HBM2DDL_AUTO, "create");
+        return dbSettings;
     }
 }