merge

.travis.yml

@@ -4,7 +4,7 @@ before_install:
   - echo "MAVEN_OPTS='-Xmx2048M -Xss128M -XX:+CMSClassUnloadingEnabled -XX:+UseG1GC -XX:-UseGCOverheadLimit'" > ~/.mavenrc
 
 install: skip
-script: travis_wait 60 mvn -q install
+script: travis_wait 60 mvn -q install -Pdefault
 
 sudo: required
 

README.md

@@ -19,7 +19,7 @@ In additional to Spring, the following technologies are in focus: `core Java`, `
 
 Building the project
 ====================
-To do the full build, do: `mvn install -Dgib.enabled=false`
+To do the full build, do: `mvn install -Pdefault -Dgib.enabled=false`
 
 
 Working with the code in Eclipse

apache-avro/pom.xml

@@ -0,0 +1,88 @@
+<?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</groupId>
+    <artifactId>apache-avro-tutorial</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <compiler-plugin.version>3.5</compiler-plugin.version>
+        <avro.version>1.8.2</avro.version>
+        <java.version>1.8</java.version>
+        <slf4j.version>1.7.25</slf4j.version>
+    </properties>
+	
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.10</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>${slf4j.version}</version>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.avro</groupId>
+            <artifactId>avro</artifactId>
+            <version>${avro.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.avro</groupId>
+            <artifactId>avro-compiler</artifactId>
+            <version>${avro.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.avro</groupId>
+            <artifactId>avro-maven-plugin</artifactId>
+            <version>${avro.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${compiler-plugin.version}</version>
+                <configuration>
+                    <source>${java.version}</source>
+                    <target>${java.version}</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.avro</groupId>
+                <artifactId>avro-maven-plugin</artifactId>
+                <version>${avro.version}</version>
+                <executions>
+                    <execution>
+                        <id>schemas</id>
+                        <phase>generate-sources</phase>
+                        <goals>
+                            <goal>schema</goal>
+                            <goal>protocol</goal>
+                            <goal>idl-protocol</goal>
+                        </goals>
+                        <configuration>
+                            <sourceDirectory>${project.basedir}/src/main/resources/</sourceDirectory>
+                            <outputDirectory>${project.basedir}/src/main/java/</outputDirectory>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

apache-avro/src/main/java/com/baeldung/avro/util/AvroClassGenerator.java

@@ -0,0 +1,14 @@
+package com.baeldung.avro.util;
+
+import org.apache.avro.Schema;
+import org.apache.avro.compiler.specific.SpecificCompiler;
+
+import java.io.File;
+import java.io.IOException;
+
+public class AvroClassGenerator {
+    public void generateAvroClasses() throws IOException {
+        SpecificCompiler compiler = new SpecificCompiler(new Schema.Parser().parse(new File("src/main/resources/avroHttpRequest-schema.avsc")));
+        compiler.compileToDestination(new File("src/main/resources"), new File("src/main/java")); 
+    }
+}

apache-avro/src/main/java/com/baeldung/avro/util/AvroSchemaBuilder.java

@@ -0,0 +1,24 @@
+package com.baeldung.avro.util;
+
+
+import org.apache.avro.Schema;
+import org.apache.avro.SchemaBuilder;
+
+public class AvroSchemaBuilder {
+
+    public Schema createAvroHttpRequestSchema(){
+
+        Schema clientIdentifier = SchemaBuilder.record("ClientIdentifier").namespace("com.baeldung.avro.model")
+                .fields().requiredString("hostName").requiredString("ipAddress").endRecord();
+
+        Schema avroHttpRequest = SchemaBuilder.record("AvroHttpRequest").namespace("com.baeldung.avro.model").fields()
+                .requiredLong("requestTime")
+                .name("clientIdentifier").type(clientIdentifier).noDefault()
+                .name("employeeNames").type().array().items().stringType().arrayDefault(null)
+                .name("active").type().enumeration("Active").symbols("YES", "NO").noDefault()
+                .endRecord();
+        return avroHttpRequest;
+    }
+}
+
+

apache-avro/src/main/java/com/baeldung/avro/util/model/Active.java

@@ -0,0 +1,13 @@
+/**
+ * Autogenerated by Avro
+ *
+ * DO NOT EDIT DIRECTLY
+ */
+package com.baeldung.avro.util.model;
+@SuppressWarnings("all")
+@org.apache.avro.specific.AvroGenerated
+public enum Active {
+  YES, NO  ;
+  public static final org.apache.avro.Schema SCHEMA$ = new org.apache.avro.Schema.Parser().parse("{\"type\":\"enum\",\"name\":\"Active\",\"namespace\":\"com.baeldung.avro.model\",\"symbols\":[\"YES\",\"NO\"]}");
+  public static org.apache.avro.Schema getClassSchema() { return SCHEMA$; }
+}

apache-avro/src/main/java/com/baeldung/avro/util/serealization/AvroDeSerealizer.java

@@ -0,0 +1,33 @@
+package com.baeldung.avro.util.serealization;
+
+import com.baeldung.avro.util.model.AvroHttpRequest;
+import org.apache.avro.io.DatumReader;
+import org.apache.avro.io.Decoder;
+import org.apache.avro.io.DecoderFactory;
+import org.apache.avro.specific.SpecificDatumReader;
+
+import java.io.IOException;
+
+public class AvroDeSerealizer {
+
+public AvroHttpRequest deSerealizeAvroHttpRequestJSON(byte[] data){
+    DatumReader<AvroHttpRequest> reader = new SpecificDatumReader<>(AvroHttpRequest.class);
+    Decoder decoder = null;
+    try {
+        decoder = DecoderFactory.get().jsonDecoder(AvroHttpRequest.getClassSchema(), new String(data));
+        return reader.read(null, decoder);
+    } catch (IOException e) {
+        return null;
+    }
+}
+
+public AvroHttpRequest deSerealizeAvroHttpRequestBinary(byte[] data){
+    DatumReader<AvroHttpRequest> employeeReader = new SpecificDatumReader<>(AvroHttpRequest.class);
+    Decoder decoder = DecoderFactory.get().binaryDecoder(data, null);
+    try {
+        return employeeReader.read(null, decoder);
+    } catch (IOException e) {
+        return null;
+    }
+}
+}

apache-avro/src/main/java/com/baeldung/avro/util/serealization/AvroSerealizer.java

@@ -0,0 +1,44 @@
+package com.baeldung.avro.util.serealization;
+
+import com.baeldung.avro.util.model.AvroHttpRequest;
+import org.apache.avro.io.*;
+import org.apache.avro.specific.SpecificDatumWriter;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+public class AvroSerealizer {
+
+public byte[] serealizeAvroHttpRequestJSON(AvroHttpRequest request){
+    DatumWriter<AvroHttpRequest> writer = new SpecificDatumWriter<>(AvroHttpRequest.class);
+    byte[] data = new byte[0];
+    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+    Encoder jsonEncoder = null;
+    try {
+        jsonEncoder = EncoderFactory.get().jsonEncoder(AvroHttpRequest.getClassSchema(), stream);
+        writer.write(request, jsonEncoder);
+        jsonEncoder.flush();
+        data = stream.toByteArray();
+    } catch (IOException e) {
+        data =null;
+    }
+    return data;
+}
+
+public byte[] serealizeAvroHttpRequestBinary(AvroHttpRequest request){
+    DatumWriter<AvroHttpRequest> writer = new SpecificDatumWriter<>(AvroHttpRequest.class);
+    byte[] data = new byte[0];
+    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+    Encoder jsonEncoder = EncoderFactory.get().binaryEncoder(stream,null);
+    try {
+        writer.write(request, jsonEncoder);
+        jsonEncoder.flush();
+        data = stream.toByteArray();
+    } catch (IOException e) {
+        data = null;
+    }
+
+    return data;
+}
+
+}

apache-avro/src/main/resources/avroHttpRequest-schema.avsc

@@ -0,0 +1,47 @@
+{
+  "type":"record",
+  "name":"AvroHttpRequest",
+  "namespace":"com.baeldung.avro.model",
+  "fields":[
+    {
+      "name":"requestTime",
+      "type":"long"
+    },
+    {
+      "name":"clientIdentifier",
+      "type":{
+        "type":"record",
+        "name":"ClientIdentifier",
+        "fields":[
+          {
+            "name":"hostName",
+            "type":"string"
+          },
+          {
+            "name":"ipAddress",
+            "type":"string"
+          }
+        ]
+      }
+    },
+    {
+      "name":"employeeNames",
+      "type":{
+        "type":"array",
+        "items":"string"
+      },
+      "default":null
+    },
+    {
+      "name":"active",
+      "type":{
+        "type":"enum",
+        "name":"Active",
+        "symbols":[
+          "YES",
+          "NO"
+        ]
+      }
+    }
+  ]
+}

apache-avro/src/test/java/com/baeldung/avro/util/serealization/AvroSerealizerDeSerealizerTest.java

@@ -0,0 +1,75 @@
+package com.baeldung.avro.util.serealization;
+
+import com.baeldung.avro.util.model.Active;
+import com.baeldung.avro.util.model.AvroHttpRequest;
+import com.baeldung.avro.util.model.ClientIdentifier;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+import static org.junit.Assert.*;
+
+public class AvroSerealizerDeSerealizerTest {
+
+    AvroSerealizer serealizer;
+    AvroDeSerealizer deSerealizer;
+    AvroHttpRequest request;
+
+    @Before
+    public void setUp() throws Exception {
+        serealizer = new AvroSerealizer();
+        deSerealizer = new AvroDeSerealizer();
+
+        ClientIdentifier clientIdentifier = ClientIdentifier.newBuilder().
+                setHostName("localhost").setIpAddress("255.255.255.0").build();
+
+        List<CharSequence> employees = new ArrayList();
+        employees.add("James");
+        employees.add("Alice");
+        employees.add("David");
+        employees.add("Han");
+
+        request = AvroHttpRequest.newBuilder().setRequestTime(01l)
+                .setActive(Active.YES).setClientIdentifier(clientIdentifier)
+                .setEmployeeNames(employees).build();
+    }
+
+    @After
+    public void tearDown() throws Exception {
+    }
+
+@Test
+public void WhenSerialized_UsingJSONEncoder_ObjectGetsSerialized(){
+    byte[] data = serealizer.serealizeAvroHttpRequestJSON(request);
+    assertTrue(Objects.nonNull(data));
+    assertTrue(data.length > 0);
+}
+
+@Test
+public void WhenSerialized_UsingBinaryEncoder_ObjectGetsSerialized(){
+    byte[] data = serealizer.serealizeAvroHttpRequestBinary(request);
+    assertTrue(Objects.nonNull(data));
+    assertTrue(data.length > 0);
+}
+
+@Test
+public void WhenDeserialize_UsingJSONDecoder_ActualAndExpectedObjectsAreEqual(){
+    byte[] data = serealizer.serealizeAvroHttpRequestJSON(request);
+    AvroHttpRequest actualRequest = deSerealizer.deSerealizeAvroHttpRequestJSON(data);
+    assertEquals(actualRequest,request);
+    assertTrue(actualRequest.getRequestTime().equals(request.getRequestTime()));
+}
+
+@Test
+public void WhenDeserialize_UsingBinaryecoder_ActualAndExpectedObjectsAreEqual(){
+    byte[] data = serealizer.serealizeAvroHttpRequestBinary(request);
+    AvroHttpRequest actualRequest = deSerealizer.deSerealizeAvroHttpRequestBinary(data);
+    assertEquals(actualRequest,request);
+    assertTrue(actualRequest.getRequestTime().equals(request.getRequestTime()));
+}
+}
+

bootique/pom.xml

@@ -52,16 +52,21 @@
 
     <build>
         <plugins>
+
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
+                <version>${maven-shade-plugin.version}</version>
             </plugin>
+
         </plugins>
     </build>
 
     <properties>
         <main.class>com.baeldung.bootique.App</main.class>
         <bootique-bom.version>0.23</bootique-bom.version>
+
+        <maven-shade-plugin.version>2.4.3</maven-shade-plugin.version>
     </properties>
 
 </project>

core-java-10/src/test/java/com/baeldung/java10/list/CopyListServiceUnitTest.java

@@ -0,0 +1,14 @@
+package com.baeldung.java10.list;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class CopyListServiceUnitTest {
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void whenModifyCopyOfList_thenThrowsException() {
+        List<Integer> copyList = List.copyOf(Arrays.asList(1, 2, 3, 4));
+    }
+}

core-java-8/pom.xml

@@ -128,77 +128,6 @@
                 </executions>
             </plugin>
 
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-jar-plugin</artifactId>
-                <configuration>
-                    <archive>
-                        <manifest>
-                            <addClasspath>true</addClasspath>
-                            <classpathPrefix>libs/</classpathPrefix>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                        </manifest>
-                    </archive>
-                </configuration>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-assembly-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <phase>package</phase>
-                        <goals>
-                            <goal>single</goal>
-                        </goals>
-                        <configuration>
-                            <archiveBaseDirectory>${project.basedir}</archiveBaseDirectory>
-                            <archive>
-                                <manifest>
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                                </manifest>
-                            </archive>
-                            <descriptorRefs>
-                                <descriptorRef>jar-with-dependencies</descriptorRef>
-                            </descriptorRefs>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-shade-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <goals>
-                            <goal>shade</goal>
-                        </goals>
-                        <configuration>
-                            <shadedArtifactAttached>true</shadedArtifactAttached>
-                            <transformers>
-                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                                </transformer>
-                            </transformers>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
-            <plugin>
-                <groupId>com.jolira</groupId>
-                <artifactId>onejar-maven-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <configuration>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                            <attachToBuild>true</attachToBuild>
-                            <filename>${project.build.finalName}-onejar.${project.packaging}</filename>
-                        </configuration>
-                        <goals>
-                            <goal>one-jar</goal>
-                        </goals>
-                    </execution>
-                </executions>
-            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>

core-java-8/src/main/java/com/baeldung/convertlisttomap/Animal.java

@@ -0,0 +1,27 @@
+package com.baeldung.convertlisttomap;
+
+public class Animal {
+    private int id;
+    private String name;
+
+    public Animal(int id, String name) {
+        this.id = id;
+        this.setName(name);
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

core-java-8/src/main/java/com/baeldung/convertlisttomap/ConvertListToMapService.java

@@ -0,0 +1,52 @@
+package com.baeldung.convertlisttomap;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import org.apache.commons.collections4.IterableUtils;
+import org.apache.commons.collections4.MapUtils;
+import com.google.common.collect.Maps;
+
+public class ConvertListToMapService {
+
+    public Map<Integer, Animal> convertListBeforeJava8(List<Animal> list) {
+        Map<Integer, Animal> map = new HashMap<Integer, Animal>();
+        for (Animal animal : list) {
+            map.put(animal.getId(), animal);
+        }
+        return map;
+    }
+
+    public Map<Integer, Animal> convertListAfterJava8(List<Animal> list) {
+        Map<Integer, Animal> map = list.stream().collect(Collectors.toMap(Animal::getId, animal -> animal));
+        return map;
+    }
+
+    public Map<Integer, Animal> convertListWithGuava(List<Animal> list) {
+
+        Map<Integer, Animal> map = Maps.uniqueIndex(list, Animal::getId);
+        return map;
+    }
+
+    public Map<Integer, Animal> convertListWithApacheCommons1(List<Animal> list) {
+
+        Map<Integer, Animal> map = new HashMap<Integer, Animal>();
+
+        IterableUtils.forEach(list, animal -> {
+            map.put(animal.getId(), animal);
+        });
+
+        return map;
+    }
+
+    public Map<Integer, Animal> convertListWithApacheCommons2(List<Animal> list) {
+
+        Map<Integer, Animal> map = new HashMap<Integer, Animal>();
+
+        MapUtils.populateMap(map, list, Animal::getId);
+
+        return map;
+    }
+}

core-java-8/src/main/java/com/baeldung/list/CopyListService.java

@@ -0,0 +1,73 @@
+package com.baeldung.list;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class CopyListService {
+
+    public List<Flower> copyListByConstructor(List<Flower> source) {
+        return new ArrayList<Flower>(source);
+    }
+
+    public List<Flower> copyListByConstructorAndEditOneFlowerInTheNewList(List<Flower> source) {
+        List<Flower> flowers = new ArrayList<>(source);
+        if(flowers.size() > 0) {
+            flowers.get(0).setPetals(flowers.get(0).getPetals() * 3);
+        }
+
+        return flowers;
+    }
+
+    public List<Flower> copyListByAddAllMethod(List<Flower> source) {
+        List<Flower> flowers = new ArrayList<>();
+        flowers.addAll(source);
+        return flowers;
+    }
+
+    public List<Flower> copyListByAddAllMethodAndEditOneFlowerInTheNewList(List<Flower> source) {
+        List<Flower> flowers = new ArrayList<>();
+        flowers.addAll(source);
+
+        if(flowers.size() > 0) {
+            flowers.get(0).setPetals(flowers.get(0).getPetals() * 3);
+        }
+
+        return flowers;
+    }
+
+    public List<Integer> copyListByCopyMethod(List<Integer> source, List<Integer> dest) {
+        Collections.copy(dest, source);
+        return dest;
+    }
+
+    public List<Flower> copyListByStream(List<Flower> source) {
+        return source.stream().collect(Collectors.toList());
+    }
+
+    public List<Flower> copyListByStreamAndSkipFirstElement(List<Flower> source) {
+        return source.stream().skip(1).collect(Collectors.toList());
+    }
+
+    public List<Flower> copyListByStreamWithFilter(List<Flower> source, Integer moreThanPetals) {
+        return source.stream().filter(f -> f.getPetals() > moreThanPetals).collect(Collectors.toList());
+    }
+
+    public List<Flower> copyListByStreamWithOptional(List<Flower> source) {
+        return Optional.ofNullable(source)
+                 .map(List::stream)
+                 .orElseGet(Stream::empty)
+                 .collect(Collectors.toList());
+    }
+
+    public List<Flower> copyListByStreamWithOptionalAndSkip(List<Flower> source) {
+        return Optional.ofNullable(source)
+                .map(List::stream)
+                .orElseGet(Stream::empty)
+                .skip(1)
+                .collect(Collectors.toList());
+    }
+}

core-java-8/src/main/java/com/baeldung/list/Flower.java

@@ -0,0 +1,28 @@
+package com.baeldung.list;
+
+public class Flower {
+
+    private String name;
+    private int petals;
+
+    public Flower(String name, int petals) {
+        this.name = name;
+        this.petals = petals;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getPetals() {
+        return petals;
+    }
+
+    public void setPetals(int petals) {
+        this.petals = petals;
+    }
+}

core-java-8/src/test/java/com/baeldung/convertlisttomap/ConvertListToMapServiceUnitTest.java

@@ -0,0 +1,73 @@
+package com.baeldung.convertlisttomap;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class ConvertListToMapServiceUnitTest {
+    List<Animal> list;
+
+    private ConvertListToMapService convertListService;
+
+    @Before
+    public void init() {
+        this.convertListService = new ConvertListToMapService();
+        this.list = new ArrayList<>();
+
+        Animal cat = new Animal(1, "Cat");
+        list.add(cat);
+        Animal dog = new Animal(2, "Dog");
+        list.add(dog);
+        Animal pig = new Animal(3, "Pig");
+        list.add(pig);
+        Animal cow = new Animal(4, "Cow");
+        list.add(cow);
+        Animal goat = new Animal(5, "Goat");
+        list.add(goat);
+    }
+
+    @Test
+    public void givenAList_whenConvertBeforeJava8_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListBeforeJava8(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+
+    @Test
+    public void givenAList_whenConvertAfterJava8_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListAfterJava8(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+
+    @Test
+    public void givenAList_whenConvertWithGuava_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListWithGuava(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+
+    @Test
+    public void givenAList_whenConvertWithApacheCommons1_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListWithApacheCommons1(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+
+    @Test
+    public void givenAList_whenConvertWithApacheCommons2_thenReturnMapWithTheSameElements() {
+
+        Map<Integer, Animal> map = convertListService.convertListWithApacheCommons2(list);
+
+        assertThat(map.values(), containsInAnyOrder(list.toArray()));
+    }
+}

core-java-8/src/test/java/com/baeldung/list/CopyListServiceUnitTest.java

@@ -0,0 +1,129 @@
+package com.baeldung.list;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.*;
+
+public class CopyListServiceUnitTest {
+
+    List<Flower> flowers;
+
+    private CopyListService copyListService;
+
+    @Before
+    public void init() {
+        this.copyListService = new CopyListService();
+        this.flowers = new ArrayList<>();
+
+        Flower poppy = new Flower("Poppy", 12);
+        flowers.add(poppy);
+        Flower anemone = new Flower("Anemone", 8);
+        flowers.add(anemone);
+        Flower catmint = new Flower("Catmint", 12);
+        flowers.add(catmint);
+        Flower diascia = new Flower("Diascia", 5);
+        flowers.add(diascia);
+        Flower iris = new Flower("Iris", 3);
+        flowers.add(iris);
+        Flower pansy = new Flower("Pansy", 5);
+        flowers.add(pansy);
+    }
+
+    @Test
+    public void givenAList_whenListDoesNotHaveNullElements_thenReturnAnotherListWithTheSameElementsByConstructor() {
+        List<Flower> copy = copyListService.copyListByConstructor(flowers);
+        assertEquals(copy.size(), flowers.size());
+        assertTrue(copy.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListDoesNotHaveNullElements_thenReturnAnotherListWithOneModifiedElementByConstructor() {
+        List<Flower> copy = copyListService.copyListByConstructorAndEditOneFlowerInTheNewList(flowers);
+        assertEquals(copy.size(), flowers.size());
+        assertTrue(copy.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListDoesNotHaveNullElements_thenReturnAnotherListWithTheSameElementsByAddAllmethod() {
+        List<Flower> copy = copyListService.copyListByAddAllMethod(flowers);
+        assertEquals(copy.size(), flowers.size());
+        assertTrue(copy.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListDoesNotHaveNullElements_thenReturnAnotherListWithOneModifiedElementByAddAllmethod() {
+        List<Flower> copy = copyListService.copyListByAddAllMethodAndEditOneFlowerInTheNewList(flowers);
+        assertEquals(copy.size(), flowers.size());
+        assertTrue(copy.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListsHaveSameSize_thenReturnAnotherListWithTheSameElementsByCopyMethod() {
+        List<Integer> source = Arrays.asList(1,2,3);
+        List<Integer> dest = Arrays.asList(4,5,6);
+
+        dest = copyListService.copyListByCopyMethod(source, dest);
+        assertEquals(dest.size(), source.size());
+        assertTrue(dest.containsAll(source));
+    }
+
+    @Test
+    public void givenAList_whenListsHaveDifferentSize_thenReturnAnotherListWithTheSameElementsByCopyMethod() {
+        List<Integer> source = Arrays.asList(1,2,3);
+        List<Integer> dest = Arrays.asList(5,6,7,8,9,10);
+
+        dest = copyListService.copyListByCopyMethod(source, dest);
+        assertNotEquals(dest.size(), source.size());
+        assertTrue(dest.containsAll(source));
+    }
+
+    @Test
+    public void givenAList_whenListDoesNotHaveNullElements_thenReturnAnotherListWithTheSameElementsByStreamProcess() {
+        List<Flower> copy = copyListService.copyListByStream(flowers);
+        assertEquals(copy.size(), flowers.size());
+        assertTrue(copy.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListDoesNotHaveNullElements_thenReturnAnotherListWithOneElementLessByStreamProcess() {
+        List<Flower> copy = copyListService.copyListByStreamAndSkipFirstElement(flowers);
+        assertNotEquals(copy.size(), flowers.size());
+        assertEquals(copy.size() + 1, flowers.size());
+        assertFalse(copy.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListDoesNotHaveNullElements_thenReturnAnotherListWithFilterElementsByStreamProcess() {
+        List<Flower> copy = copyListService.copyListByStreamWithFilter(flowers, 5);
+        assertNotEquals(copy.size(), flowers.size());
+        assertEquals(copy.size() + 3, flowers.size());
+        assertFalse(copy.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListIsNull_thenReturnEmptyListByStreamProcess() {
+        List<Flower> copy = copyListService.copyListByStreamWithOptional(null);
+        assertNotNull(copy);
+        assertEquals(copy.size(), 0);
+    }
+
+    @Test
+    public void givenAList_whenListIsNotNull_thenReturnAnotherListWithTheElementsByStreamProcess() {
+        List<Flower> copy = copyListService.copyListByStreamWithOptional(flowers);
+        assertEquals(copy.size(), flowers.size());
+        assertTrue(copy.containsAll(flowers));
+    }
+
+    @Test
+    public void givenAList_whenListIsNotNull_thenReturnAnotherListWithOneElementLessByStreamProcess() {
+        List<Flower> copy = copyListService.copyListByStreamWithOptionalAndSkip(flowers);
+        assertNotEquals(copy.size(), flowers.size());
+        assertEquals(copy.size() + 1, flowers.size());
+        assertFalse(copy.containsAll(flowers));
+    }
+}

core-java-collections/src/test/java/com/baeldung/java/set/HashSetInitalizingUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.java.set;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+import org.junit.jupiter.api.Test;
+  
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.assertEquals;
+
+public class HashSetInitalizingUnitTest {
+    @Test
+    public void whenUsingJava_usingArraysStaticMethod_thenCorrectSize() {
+        Set<String> set = new HashSet<>(Arrays.asList("a", "b", "c"));
+        assertEquals(3, set.size());
+    }
+
+    @Test
+    public void whenUsingJava_usingAnonymousClass_thenCorrectSize() {
+        Set<String> set = new HashSet<String>(){{
+            add("a");
+            add("b");
+            add("c");
+        }};
+        assertEquals(3, set.size());
+    }
+
+    @Test
+    public void whenUsingJava_creatingSingletonSet_thenCorrectSize() {
+        Set<String> set = Collections.singleton("a");
+        assertEquals(1, set.size());
+    }
+
+    public static final <T> Set<T> newHashSet(T... objs) {
+        Set<T> set = new HashSet<T>();
+        Collections.addAll(set, objs);
+        return set;
+    }
+
+    @Test
+    public void whenUsingJava_usingCustomStaticUtilMethod_thenCorrectSize() {
+        Set<String> set = newHashSet("a","b","c");
+        assertEquals(3, set.size());
+    }
+
+    @Test
+    public void whenUsingJava8_usingCollectOnStream_thenCorrectSize() {
+        Set<String> set = Stream.of("a", "b", "c").collect(Collectors.toCollection(HashSet::new));
+        assertEquals(3, set.size());
+    }
+
+    @Test
+    public void whenUsingGoogleGuava_createMutableSet_thenCorrectSize() {
+        Set<String> set = Sets.newHashSet("a", "b", "c");
+        assertEquals(3, set.size());
+    }
+
+    @Test
+    public void whenUsingGoogleGuava_createImmutableSet_thenCorrectSize() {
+        Set<String> set = ImmutableSet.of("a", "b", "c");
+        assertEquals(3, set.size());
+    }
+  
+}
+

core-java-concurrency/pom.xml

@@ -75,92 +75,7 @@
                     </execution>
                 </executions>
             </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-jar-plugin</artifactId>
-                <configuration>
-                    <archive>
-                        <manifest>
-                            <addClasspath>true</addClasspath>
-                            <classpathPrefix>libs/</classpathPrefix>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                        </manifest>
-                    </archive>
-                </configuration>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-assembly-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <phase>package</phase>
-                        <goals>
-                            <goal>single</goal>
-                        </goals>
-                        <configuration>
-                            <archiveBaseDirectory>${project.basedir}</archiveBaseDirectory>
-                            <archive>
-                                <manifest>
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                                </manifest>
-                            </archive>
-                            <descriptorRefs>
-                                <descriptorRef>jar-with-dependencies</descriptorRef>
-                            </descriptorRefs>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-shade-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <goals>
-                            <goal>shade</goal>
-                        </goals>
-                        <configuration>
-                            <shadedArtifactAttached>true</shadedArtifactAttached>
-                            <transformers>
-                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                                </transformer>
-                            </transformers>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
-            <plugin>
-                <groupId>com.jolira</groupId>
-                <artifactId>onejar-maven-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <configuration>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                            <attachToBuild>true</attachToBuild>
-                            <filename>${project.build.finalName}-onejar.${project.packaging}</filename>
-                        </configuration>
-                        <goals>
-                            <goal>one-jar</goal>
-                        </goals>
-                    </execution>
-                </executions>
-            </plugin>
-            <plugin>
-                <groupId>org.springframework.boot</groupId>
-                <artifactId>spring-boot-maven-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <goals>
-                            <goal>repackage</goal>
-                        </goals>
-                        <configuration>
-                            <classifier>spring-boot</classifier>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
+            
         </plugins>
     </build>
 

core-java-sun/pom.xml

@@ -185,6 +185,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-jar-plugin</artifactId>
+                <version>${maven-jar-plugin.version}</version>
                 <configuration>
                     <archive>
                         <manifest>
@@ -195,79 +196,6 @@
                     </archive>
                 </configuration>
             </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-assembly-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <phase>package</phase>
-                        <goals>
-                            <goal>single</goal>
-                        </goals>
-                        <configuration>
-                            <archiveBaseDirectory>${project.basedir}</archiveBaseDirectory>
-                            <archive>
-                                <manifest>
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                                </manifest>
-                            </archive>
-                            <descriptorRefs>
-                                <descriptorRef>jar-with-dependencies</descriptorRef>
-                            </descriptorRefs>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-shade-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <goals>
-                            <goal>shade</goal>
-                        </goals>
-                        <configuration>
-                            <shadedArtifactAttached>true</shadedArtifactAttached>
-                            <transformers>
-                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                                </transformer>
-                            </transformers>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
-            <plugin>
-                <groupId>com.jolira</groupId>
-                <artifactId>onejar-maven-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <configuration>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                            <attachToBuild>true</attachToBuild>
-                            <filename>${project.build.finalName}-onejar.${project.packaging}</filename>
-                        </configuration>
-                        <goals>
-                            <goal>one-jar</goal>
-                        </goals>
-                    </execution>
-                </executions>
-            </plugin>
-            <plugin>
-                <groupId>org.springframework.boot</groupId>
-                <artifactId>spring-boot-maven-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <goals>
-                            <goal>repackage</goal>
-                        </goals>
-                        <configuration>
-                            <classifier>spring-boot</classifier>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>exec-maven-plugin</artifactId>
@@ -368,6 +296,7 @@
         <protonpack.version>1.13</protonpack.version>
         <streamex.version>0.6.5</streamex.version>
         <vavr.version>0.9.0</vavr.version>
+        <spring-web.version>4.3.4.RELEASE</spring-web.version>
 
         <!-- testing -->
         <assertj.version>3.6.1</assertj.version>
@@ -376,7 +305,7 @@
         <!-- maven plugins -->
         <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
         <sun-tools.version>1.8.0</sun-tools.version>
-        <spring-web.version>4.3.4.RELEASE</spring-web.version>
+        <maven-jar-plugin.version>3.0.2</maven-jar-plugin.version>
     </properties>
 
 </project>

core-java/pom.xml

@@ -1,5 +1,5 @@
 <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">
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <artifactId>core-java</artifactId>
@@ -73,9 +73,10 @@
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
+            <version>${assertj-core.version}</version>
             <scope>test</scope>
         </dependency>
+
         <dependency>
             <groupId>commons-codec</groupId>
             <artifactId>commons-codec</artifactId>
@@ -146,6 +147,21 @@
             <artifactId>icu4j</artifactId>
             <version>${icu4j.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-dbcp2</artifactId>
+            <version>${commons-dbcp2.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.zaxxer</groupId>
+            <artifactId>HikariCP</artifactId>
+            <version>${HikariCP.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.mchange</groupId>
+            <artifactId>c3p0</artifactId>
+            <version>${c3p0.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -301,7 +317,7 @@
                     </arguments>
                 </configuration>
             </plugin>
-
+            
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
@@ -348,6 +364,7 @@
                     <plugin>
                         <groupId>org.codehaus.mojo</groupId>
                         <artifactId>exec-maven-plugin</artifactId>
+                        <version>${exec-maven-plugin.version}</version>
                         <executions>
                             <execution>
                                 <id>run-benchmarks</id>
@@ -375,6 +392,7 @@
     </profiles>
 
     <properties>
+        
         <!-- marshalling -->
         <jackson.version>2.8.5</jackson.version>
         <gson.version>2.8.2</gson.version>
@@ -395,16 +413,23 @@
         <vavr.version>0.9.0</vavr.version>
 
         <!-- testing -->
-        <assertj.version>3.6.1</assertj.version>
+        <assertj-core.version>3.10.0</assertj-core.version>
 
+        <!-- JDBC pooling frameworks -->
+        <commons-dbcp2.version>2.4.0</commons-dbcp2.version>
+        <HikariCP.version>3.2.0</HikariCP.version>
+        <c3p0.version>0.9.5.2</c3p0.version>
+        
         <!-- maven plugins -->
         <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
         <springframework.spring-web.version>4.3.4.RELEASE</springframework.spring-web.version>
         <springframework.boot.spring-boot-starter.version>1.5.8.RELEASE</springframework.boot.spring-boot-starter.version>
+        
         <javamoney.moneta.version>1.1</javamoney.moneta.version>
         <h2database.version>1.4.197</h2database.version>
         <esapi.version>2.1.0.1</esapi.version>
         <jmh-core.version>1.19</jmh-core.version>
+       
         <jmh-generator-annprocess.version>1.19</jmh-generator-annprocess.version>
         <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
         <javax.mail.version>1.5.0-b01</javax.mail.version>
@@ -412,7 +437,8 @@
         <onejar-maven-plugin.version>1.4.4</onejar-maven-plugin.version>
         <maven-shade-plugin.version>3.1.1</maven-shade-plugin.version>
         <spring-boot-maven-plugin.version>2.0.3.RELEASE</spring-boot-maven-plugin.version>
+        <exec-maven-plugin.version>1.6.0</exec-maven-plugin.version>
         <icu4j.version>61.1</icu4j.version>
     </properties>
 
-</project>
+</project>

core-java/src/main/java/com/baeldung/connectionpool/connectionpools/BasicConnectionPool.java

@@ -0,0 +1,87 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BasicConnectionPool implements ConnectionPool {
+
+    private final String url;
+    private final String user;
+    private final String password;
+    private final List<Connection> connectionPool;
+    private final List<Connection> usedConnections = new ArrayList<>();
+    private static final int INITIAL_POOL_SIZE = 10;
+    private final int MAX_POOL_SIZE = 20;
+    
+    public static BasicConnectionPool create(String url, String user, String password) throws SQLException {
+        List<Connection> pool = new ArrayList<>(INITIAL_POOL_SIZE);
+        for (int i = 0; i < INITIAL_POOL_SIZE; i++) {
+            pool.add(createConnection(url, user, password));
+        }
+        return new BasicConnectionPool(url, user, password, pool);
+    }
+    
+    private BasicConnectionPool(String url, String user, String password, List<Connection> connectionPool) {
+        this.url = url;
+        this.user = user;
+        this.password = password;
+        this.connectionPool = connectionPool;
+    }
+    
+    @Override
+    public Connection getConnection() throws SQLException {
+        if (connectionPool.size() == 0) {
+            if (usedConnections.size() < MAX_POOL_SIZE) {
+                connectionPool.add(createConnection(url, user, password));
+            } else {
+                throw new RuntimeException("Maximum pool size reached, no available connections!");
+            }
+        }
+
+        Connection connection = connectionPool.remove(connectionPool.size() - 1);
+        usedConnections.add(connection);
+        return connection;
+    }
+    
+    @Override
+    public boolean releaseConnection(Connection connection) {
+        connectionPool.add(connection);
+        return usedConnections.remove(connection);
+    }
+    
+    private static Connection createConnection(String url, String user, String password) throws SQLException {
+        return DriverManager.getConnection(url, user, password);
+    }
+    
+    public int getSize() {
+        return connectionPool.size() + usedConnections.size();
+    }
+
+    @Override
+    public String getUrl() {
+        return url;
+    }
+
+    @Override
+    public String getUser() {
+        return user;
+    }
+
+    @Override
+    public String getPassword() {
+        return password;
+    }
+
+    public void shutdown() throws SQLException {
+        for (Connection c : usedConnections) {
+            this.releaseConnection(c);
+        }
+        for (Connection c : connectionPool) {
+            c.close();
+        }
+        connectionPool.clear();
+    }
+}

core-java/src/main/java/com/baeldung/connectionpool/connectionpools/C3poDataSource.java

@@ -0,0 +1,28 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import com.mchange.v2.c3p0.ComboPooledDataSource;
+import java.beans.PropertyVetoException;
+import java.sql.Connection;
+import java.sql.SQLException;
+
+public class C3poDataSource {
+
+    private static final ComboPooledDataSource cpds = new ComboPooledDataSource();
+
+    static {
+        try {
+            cpds.setDriverClass("org.h2.Driver");
+            cpds.setJdbcUrl("jdbc:h2:mem:test");
+            cpds.setUser("user");
+            cpds.setPassword("password");
+        } catch (PropertyVetoException e) {
+            e.printStackTrace();
+        }
+    }
+    
+    public static Connection getConnection() throws SQLException {
+        return cpds.getConnection();
+    }
+    
+    private C3poDataSource(){}
+}

core-java/src/main/java/com/baeldung/connectionpool/connectionpools/ConnectionPool.java

@@ -0,0 +1,18 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.List;
+
+public interface ConnectionPool {
+
+    Connection getConnection() throws SQLException;
+    
+    boolean releaseConnection(Connection connection);
+    
+    String getUrl();
+    
+    String getUser();
+
+    String getPassword();
+}   

core-java/src/main/java/com/baeldung/connectionpool/connectionpools/DBCPDataSource.java

@@ -0,0 +1,25 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import org.apache.commons.dbcp2.BasicDataSource;
+
+public class DBCPDataSource {
+    
+    private static final BasicDataSource ds = new BasicDataSource();
+    
+    static {
+        ds.setUrl("jdbc:h2:mem:test");
+        ds.setUsername("user");
+        ds.setPassword("password");
+        ds.setMinIdle(5);
+        ds.setMaxIdle(10);
+        ds.setMaxOpenPreparedStatements(100);
+    }
+    
+    public static Connection getConnection() throws SQLException {
+        return ds.getConnection();
+    }
+    
+    private DBCPDataSource(){}
+}

core-java/src/main/java/com/baeldung/connectionpool/connectionpools/HikariCPDataSource.java

@@ -0,0 +1,28 @@
+package com.baeldung.connectionpool.connectionpools;
+
+import com.zaxxer.hikari.HikariConfig;
+import com.zaxxer.hikari.HikariDataSource;
+import java.sql.Connection;
+import java.sql.SQLException;
+
+public class HikariCPDataSource {
+    
+    private static final HikariConfig config = new HikariConfig();
+    private static final HikariDataSource ds;
+    
+    static {
+        config.setJdbcUrl("jdbc:h2:mem:test");
+        config.setUsername("user");
+        config.setPassword("password");
+        config.addDataSourceProperty("cachePrepStmts", "true");
+        config.addDataSourceProperty("prepStmtCacheSize", "250");
+        config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
+        ds = new HikariDataSource(config);
+    }
+    
+    public static Connection getConnection() throws SQLException {
+        return ds.getConnection();
+    }
+    
+    private HikariCPDataSource(){}
+}