Merge branch 'master' of https://github.com/eugenp/tutorials into BAEL-14776

README.md

@@ -20,17 +20,22 @@ In additional to Spring, the following technologies are in focus: `core Java`, `
 
 Building the project
 ====================
-To do the full build, do: `mvn install -Pdefault -Dgib.enabled=false`
+To do the full build, do: `mvn clean install`
 
 
 Building a single module
 ====================
-To build a specific module run the command: `mvn clean install -Dgib.enabled=false` in the module directory
+To build a specific module run the command: `mvn clean install` in the module directory
 
 
 Running a Spring Boot module
 ====================
-To run a Spring Boot module run the command: `mvn spring-boot:run -Dgib.enabled=false` in the module directory
+To run a Spring Boot module run the command: `mvn spring-boot:run` in the module directory
+
+#Running Tests
+
+The command `mvn clean install` will run the unit tests in a module.
+To run the integration tests, use the command `mvn clean install -Pintegration-lite-first`
 
 
 

algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/graphcycledetection/domain/Graph.java

@@ -0,0 +1,51 @@
+package com.baeldung.algorithms.graphcycledetection.domain;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Graph {
+
+    private List<Vertex> vertices;
+
+    public Graph() {
+        this.vertices = new ArrayList<>();
+    }
+
+    public Graph(List<Vertex> vertices) {
+        this.vertices = vertices;
+    }
+
+    public void addVertex(Vertex vertex) {
+        this.vertices.add(vertex);
+    }
+
+    public void addEdge(Vertex from, Vertex to) {
+        from.addNeighbour(to);
+    }
+
+    public boolean hasCycle() {
+        for (Vertex vertex : vertices) {
+            if (!vertex.isVisited() && hasCycle(vertex)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public boolean hasCycle(Vertex sourceVertex) {
+        sourceVertex.setBeingVisited(true);
+
+        for (Vertex neighbour : sourceVertex.getAdjacencyList()) {
+            if (neighbour.isBeingVisited()) {
+                // backward edge exists
+                return true;
+            } else if (!neighbour.isVisited() && hasCycle(neighbour)) {
+                return true;
+            }
+        }
+
+        sourceVertex.setBeingVisited(false);
+        sourceVertex.setVisited(true);
+        return false;
+    }
+}

algorithms-miscellaneous-3/src/main/java/com/baeldung/algorithms/graphcycledetection/domain/Vertex.java

@@ -0,0 +1,56 @@
+package com.baeldung.algorithms.graphcycledetection.domain;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Vertex {
+
+    private String label;
+
+    private boolean visited;
+
+    private boolean beingVisited;
+
+    private List<Vertex> adjacencyList;
+
+    public Vertex(String label) {
+        this.label = label;
+        this.adjacencyList = new ArrayList<>();
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+    public void setLabel(String label) {
+        this.label = label;
+    }
+
+    public boolean isVisited() {
+        return visited;
+    }
+
+    public void setVisited(boolean visited) {
+        this.visited = visited;
+    }
+
+    public boolean isBeingVisited() {
+        return beingVisited;
+    }
+
+    public void setBeingVisited(boolean beingVisited) {
+        this.beingVisited = beingVisited;
+    }
+
+    public List<Vertex> getAdjacencyList() {
+        return adjacencyList;
+    }
+
+    public void setAdjacencyList(List<Vertex> adjacencyList) {
+        this.adjacencyList = adjacencyList;
+    }
+
+    public void addNeighbour(Vertex adjacent) {
+        this.adjacencyList.add(adjacent);
+    }
+}

algorithms-miscellaneous-3/src/test/java/com/baeldung/algorithms/graphcycledetection/GraphCycleDetectionUnitTest.java

@@ -0,0 +1,56 @@
+package com.baeldung.algorithms.graphcycledetection;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+import com.baeldung.algorithms.graphcycledetection.domain.Graph;
+import com.baeldung.algorithms.graphcycledetection.domain.Vertex;
+
+public class GraphCycleDetectionUnitTest {
+
+    @Test
+    public void givenGraph_whenCycleExists_thenReturnTrue() {
+
+        Vertex vertexA = new Vertex("A");
+        Vertex vertexB = new Vertex("B");
+        Vertex vertexC = new Vertex("C");
+        Vertex vertexD = new Vertex("D");
+
+        Graph graph = new Graph();
+        graph.addVertex(vertexA);
+        graph.addVertex(vertexB);
+        graph.addVertex(vertexC);
+        graph.addVertex(vertexD);
+
+        graph.addEdge(vertexA, vertexB);
+        graph.addEdge(vertexB, vertexC);
+        graph.addEdge(vertexC, vertexA);
+        graph.addEdge(vertexD, vertexC);
+
+        assertTrue(graph.hasCycle());
+    }
+
+    @Test
+    public void givenGraph_whenNoCycleExists_thenReturnFalse() {
+
+        Vertex vertexA = new Vertex("A");
+        Vertex vertexB = new Vertex("B");
+        Vertex vertexC = new Vertex("C");
+        Vertex vertexD = new Vertex("D");
+
+        Graph graph = new Graph();
+        graph.addVertex(vertexA);
+        graph.addVertex(vertexB);
+        graph.addVertex(vertexC);
+        graph.addVertex(vertexD);
+
+        graph.addEdge(vertexA, vertexB);
+        graph.addEdge(vertexB, vertexC);
+        graph.addEdge(vertexA, vertexC);
+        graph.addEdge(vertexD, vertexC);
+
+        assertFalse(graph.hasCycle());
+    }
+}

apache-geode/src/test/java/com/baeldung/geode/GeodeSamplesLiveTest.java

@@ -21,7 +21,7 @@ import java.util.stream.Stream;
 
 import static org.junit.Assert.assertEquals;
 
-public class GeodeSamplesIntegrationTest {
+public class GeodeSamplesLiveTest {
 
     ClientCache cache = null;
     Region<String, String> region = null;

apache-olingo/README.md

@@ -0,0 +1,3 @@
+## Relevant articles:
+
+- [OData Protocol Guide](https://www.baeldung.com/odata)

core-groovy-2/README.md

@@ -3,5 +3,6 @@
 ## Relevant articles:
 
 - [String Matching in Groovy](http://www.baeldung.com/)
+- [Template Engines in Groovy](https://www.baeldung.com/groovy-template-engines)
 - [Groovy def Keyword](https://www.baeldung.com/groovy-def-keyword)
-- [Pattern Matching in Strings in Groovy](https://www.baeldung.com/groovy-pattern-matching)
+- [Pattern Matching in Strings in Groovy](https://www.baeldung.com/groovy-pattern-matching)

core-groovy-2/gmavenplus-pom.xml

@@ -0,0 +1,178 @@
+<?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-groovy-2</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>core-groovy-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>${logback.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.codehaus.groovy</groupId>
+            <artifactId>groovy-all</artifactId>
+            <version>${groovy.version}</version>
+            <type>pom</type>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-runner</artifactId>
+            <version>${junit.platform.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hsqldb</groupId>
+            <artifactId>hsqldb</artifactId>
+            <version>${hsqldb.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.spockframework</groupId>
+            <artifactId>spock-core</artifactId>
+            <version>${spock-core.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <scriptSourceDirectory>src/main/groovy</scriptSourceDirectory>
+        <sourceDirectory>src/main/java</sourceDirectory>
+        <plugins>
+            <plugin>
+                <groupId>org.codehaus.gmavenplus</groupId>
+                <artifactId>gmavenplus-plugin</artifactId>
+                <version>1.7.0</version>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>execute</goal>
+                            <goal>addSources</goal>
+                            <goal>addTestSources</goal>
+                            <goal>generateStubs</goal>
+                            <goal>compile</goal>
+                            <goal>generateTestStubs</goal>
+                            <goal>compileTests</goal>
+                            <goal>removeStubs</goal>
+                            <goal>removeTestStubs</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <dependencies>
+                    <dependency>
+                        <groupId>org.codehaus.groovy</groupId>
+                        <artifactId>groovy-all</artifactId>
+                        <!-- any version of Groovy \>= 1.5.0 should work here -->
+                        <version>${groovy.version}</version>
+                        <scope>runtime</scope>
+                        <type>pom</type>
+                    </dependency>
+                </dependencies>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <artifactId>maven-failsafe-plugin</artifactId>
+                <version>${maven-failsafe-plugin.version}</version>
+                <dependencies>
+                    <dependency>
+                        <groupId>org.junit.platform</groupId>
+                        <artifactId>junit-platform-surefire-provider</artifactId>
+                        <version>${junit.platform.version}</version>
+                    </dependency>
+                </dependencies>
+                <executions>
+                    <execution>
+                        <id>junit5</id>
+                        <goals>
+                            <goal>integration-test</goal>
+                            <goal>verify</goal>
+                        </goals>
+                        <configuration>
+                            <includes>
+                                <include>**/*Test5.java</include>
+                            </includes>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>2.20.1</version>
+                <configuration>
+                <useFile>false</useFile>
+                <includes>
+                    <include>**/*Test.java</include>
+                    <include>**/*Spec.java</include>
+                </includes>
+                </configuration>
+            </plugin>
+            <!-- Maven Assembly Plugin: needed to run the jar through command line -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <version>3.1.0</version>
+                <configuration>
+                    <!-- get all project dependencies -->
+                    <descriptorRefs>
+                        <descriptorRef>jar-with-dependencies</descriptorRef>
+                    </descriptorRefs>
+                    <!-- MainClass in mainfest make a executable jar -->
+                    <archive>
+                        <manifest>
+                            <mainClass>com.baeldung.MyJointCompilationApp</mainClass>
+                        </manifest>
+                    </archive>
+
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>make-assembly</id>
+                        <!-- bind to the packaging phase -->
+                        <phase>package</phase>
+                        <goals>
+                            <goal>single</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <repositories>
+        <repository>
+            <id>central</id>
+            <url>http://jcenter.bintray.com</url>
+        </repository>
+    </repositories>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <junit.platform.version>1.0.0</junit.platform.version>
+        <hsqldb.version>2.4.0</hsqldb.version>
+        <spock-core.version>1.1-groovy-2.4</spock-core.version>
+        <commons-lang3.version>3.9</commons-lang3.version>
+        <java.version>1.8</java.version>
+        <logback.version>1.2.3</logback.version>
+        <groovy.version>2.5.7</groovy.version>
+        <gmavenplus-plugin.version>1.6</gmavenplus-plugin.version>
+    </properties>
+</project>
+

core-groovy-2/pom.xml

@@ -1,6 +1,6 @@
 <?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">
+         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-groovy-2</artifactId>
     <version>1.0-SNAPSHOT</version>
@@ -15,25 +15,20 @@
 
     <dependencies>
         <dependency>
-            <groupId>org.codehaus.groovy</groupId>
+            <groupId>org.apache.commons</groupId>
-            <artifactId>groovy</artifactId>
+            <artifactId>commons-lang3</artifactId>
-            <version>${groovy.version}</version>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>${logback.version}</version>
         </dependency>
         <dependency>
             <groupId>org.codehaus.groovy</groupId>
             <artifactId>groovy-all</artifactId>
-            <version>${groovy-all.version}</version>
-            <type>pom</type>
-        </dependency>
-        <dependency>
-            <groupId>org.codehaus.groovy</groupId>
-            <artifactId>groovy-dateutil</artifactId>
             <version>${groovy.version}</version>
-        </dependency>
+            <type>pom</type>
-        <dependency>
-            <groupId>org.codehaus.groovy</groupId>
-            <artifactId>groovy-sql</artifactId>
-            <version>${groovy-sql.version}</version>
         </dependency>
         <dependency>
             <groupId>org.junit.platform</groupId>
@@ -56,21 +51,35 @@
     </dependencies>
 
     <build>
+        <scriptSourceDirectory>src/main/groovy</scriptSourceDirectory>
+        <sourceDirectory>src/main/java</sourceDirectory>
         <plugins>
             <plugin>
-                <groupId>org.codehaus.gmavenplus</groupId>
+                <groupId>org.codehaus.groovy</groupId>
-                <artifactId>gmavenplus-plugin</artifactId>
+                <artifactId>groovy-eclipse-compiler</artifactId>
-                <version>${gmavenplus-plugin.version}</version>
+                <version>3.3.0-01</version>
-                <executions>
+                <extensions>true</extensions>
-                    <execution>
+            </plugin>
-                        <goals>
+            <plugin>
-                            <goal>addSources</goal>
+                <artifactId>maven-compiler-plugin</artifactId>
-                            <goal>addTestSources</goal>
+                <version>3.8.0</version>
-                            <goal>compile</goal>
+                <configuration>
-                            <goal>compileTests</goal>
+                    <compilerId>groovy-eclipse-compiler</compilerId>
-                        </goals>
+                    <source>${java.version}</source>
-                    </execution>
+                    <target>${java.version}</target>
-                </executions>
+                </configuration>
+                <dependencies>
+                    <dependency>
+                        <groupId>org.codehaus.groovy</groupId>
+                        <artifactId>groovy-eclipse-compiler</artifactId>
+                        <version>3.3.0-01</version>
+                    </dependency>
+                    <dependency>
+                        <groupId>org.codehaus.groovy</groupId>
+                        <artifactId>groovy-eclipse-batch</artifactId>
+                        <version>${groovy.version}-01</version>
+                    </dependency>
+                </dependencies>
             </plugin>
             <plugin>
                 <artifactId>maven-failsafe-plugin</artifactId>
@@ -101,13 +110,42 @@
                 <artifactId>maven-surefire-plugin</artifactId>
                 <version>2.20.1</version>
                 <configuration>
-                <useFile>false</useFile>
+                    <useFile>false</useFile>
-                <includes>
+                    <includes>
-                    <include>**/*Test.java</include>
+                        <include>**/*Test.java</include>
-                    <include>**/*Spec.java</include>
+                        <include>**/*Spec.java</include>
-                </includes>
+                    </includes>
                 </configuration>
             </plugin>
+            <!-- Maven Assembly Plugin: needed to run the jar through command line -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <version>3.1.0</version>
+                <configuration>
+                    <!-- get all project dependencies -->
+                    <descriptorRefs>
+                        <descriptorRef>jar-with-dependencies</descriptorRef>
+                    </descriptorRefs>
+                    <!-- MainClass in mainfest make a executable jar -->
+                    <archive>
+                        <manifest>
+                            <mainClass>com.baeldung.MyJointCompilationApp</mainClass>
+                        </manifest>
+                    </archive>
+
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>make-assembly</id>
+                        <!-- bind to the packaging phase -->
+                        <phase>package</phase>
+                        <goals>
+                            <goal>single</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
         </plugins>
     </build>
 
@@ -118,14 +156,32 @@
         </repository>
     </repositories>
 
+    <pluginRepositories>
+                <pluginRepository>
+                    <id>bintray</id>
+                    <name>Groovy Bintray</name>
+                    <url>https://dl.bintray.com/groovy/maven</url>
+                    <releases>
+                        <!-- avoid automatic updates -->
+                        <updatePolicy>never</updatePolicy>
+                    </releases>
+                    <snapshots>
+                        <enabled>false</enabled>
+                    </snapshots>
+                </pluginRepository>
+            </pluginRepositories>
+
+
     <properties>
         <junit.platform.version>1.0.0</junit.platform.version>
-        <groovy.version>2.5.6</groovy.version>
-        <groovy-all.version>2.5.6</groovy-all.version>
-        <groovy-sql.version>2.5.6</groovy-sql.version>
         <hsqldb.version>2.4.0</hsqldb.version>
         <spock-core.version>1.1-groovy-2.4</spock-core.version>
-        <gmavenplus-plugin.version>1.6</gmavenplus-plugin.version>
+        <commons-lang3.version>3.9</commons-lang3.version>
+        <java.version>1.8</java.version>
+        <maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
+        <logback.version>1.2.3</logback.version>
+        <groovy.version>2.5.7</groovy.version>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 </project>
 

core-groovy-2/src/main/groovy/com/baeldung/CalcMath.groovy

@@ -0,0 +1,25 @@
+package com.baeldung
+
+import org.slf4j.LoggerFactory
+
+class CalcMath {
+    def log = LoggerFactory.getLogger(this.getClass())
+
+    def calcSum(x, y) {
+        log.info "Executing $x + $y"
+        x + y
+    }
+
+    /**
+     * example of method that in java would throw error at compile time
+     * @param x
+     * @param y
+     * @return
+     */
+    def calcSum2(x, y) {
+        log.info "Executing $x + $y"
+        // DANGER! This won't throw a compilation issue and fail only at runtime!!!
+        calcSum3()
+        log.info("Logging an undefined variable: $z")
+    }
+}

core-groovy-2/src/main/groovy/com/baeldung/CalcScript.groovy

@@ -0,0 +1,16 @@
+package com.baeldung
+
+def calcSum(x, y) {
+    x + y
+}
+
+def calcSum2(x, y) {
+    // DANGER! The variable "log" may be undefined
+    log.info "Executing $x + $y"
+    // DANGER! This method doesn't exist!
+    calcSum3()
+    // DANGER! The logged variable "z" is undefined!
+    log.info("Logging an undefined variable: $z")
+}
+
+calcSum(1,5)

core-groovy-2/src/main/java/com/baeldung/MyJointCompilationApp.java

@@ -0,0 +1,120 @@
+package com.baeldung;
+
+import groovy.lang.*;
+import groovy.util.GroovyScriptEngine;
+import groovy.util.ResourceException;
+import groovy.util.ScriptException;
+import org.codehaus.groovy.jsr223.GroovyScriptEngineFactory;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import javax.script.ScriptEngine;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileReader;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
+
+/**
+ * Hello world!
+ *
+ */
+public class MyJointCompilationApp {
+    private final static Logger LOG = LoggerFactory.getLogger(MyJointCompilationApp.class);
+    private final GroovyClassLoader loader;
+    private final GroovyShell shell;
+    private final GroovyScriptEngine engine;
+    private final ScriptEngine engineFromFactory;
+
+    public MyJointCompilationApp() {
+        loader = new GroovyClassLoader(this.getClass().getClassLoader());
+        shell = new GroovyShell(loader, new Binding());
+
+        URL url = null;
+        try {
+            url = new File("src/main/groovy/com/baeldung/").toURI().toURL();
+        } catch (MalformedURLException e) {
+            LOG.error("Exception while creating url", e);
+        }
+        engine = new GroovyScriptEngine(new URL[] {url}, this.getClass().getClassLoader());
+        engineFromFactory = new GroovyScriptEngineFactory().getScriptEngine();
+    }
+
+    private void addWithCompiledClasses(int x, int y) {
+        LOG.info("Executing {} + {}", x, y);
+        Object result1 = new CalcScript().calcSum(x, y);
+        LOG.info("Result of CalcScript.calcSum() method is {}", result1);
+
+        Object result2 = new CalcMath().calcSum(x, y);
+        LOG.info("Result of CalcMath.calcSum() method is {}", result2);
+    }
+
+    private void addWithGroovyShell(int x, int y) throws IOException {
+        Script script = shell.parse(new File("src/main/groovy/com/baeldung/", "CalcScript.groovy"));
+        LOG.info("Executing {} + {}", x, y);
+        Object result = script.invokeMethod("calcSum", new Object[] { x, y });
+        LOG.info("Result of CalcScript.calcSum() method is {}", result);
+    }
+
+    private void addWithGroovyShellRun() throws IOException {
+        Script script = shell.parse(new File("src/main/groovy/com/baeldung/", "CalcScript.groovy"));
+        LOG.info("Executing script run method");
+        Object result = script.run();
+        LOG.info("Result of CalcScript.run() method is {}", result);
+    }
+
+    private void addWithGroovyClassLoader(int x, int y) throws IllegalAccessException, InstantiationException, IOException {
+        Class calcClass = loader.parseClass(
+          new File("src/main/groovy/com/baeldung/", "CalcMath.groovy"));
+        GroovyObject calc = (GroovyObject) calcClass.newInstance();
+        Object result = calc.invokeMethod("calcSum", new Object[] { x + 14, y + 14 });
+        LOG.info("Result of CalcMath.calcSum() method is {}", result);
+    }
+
+    private void addWithGroovyScriptEngine(int x, int y) throws IllegalAccessException,
+      InstantiationException, ResourceException, ScriptException {
+        Class<GroovyObject> calcClass = engine.loadScriptByName("CalcMath.groovy");
+        GroovyObject calc = calcClass.newInstance();
+        //WARNING the following will throw a ClassCastException
+        //((CalcMath)calc).calcSum(1,2);
+        Object result = calc.invokeMethod("calcSum", new Object[] { x, y });
+        LOG.info("Result of CalcMath.calcSum() method is {}", result);
+    }
+
+    private void addWithEngineFactory(int x, int y) throws IllegalAccessException,
+      InstantiationException, javax.script.ScriptException, FileNotFoundException {
+        Class calcClass = (Class) engineFromFactory.eval(
+          new FileReader(new File("src/main/groovy/com/baeldung/", "CalcMath.groovy")));
+        GroovyObject calc = (GroovyObject) calcClass.newInstance();
+        Object result = calc.invokeMethod("calcSum", new Object[] { x, y });
+        LOG.info("Result of CalcMath.calcSum() method is {}", result);
+    }
+
+    private void addWithStaticCompiledClasses() {
+        LOG.info("Running the Groovy classes compiled statically...");
+        addWithCompiledClasses(5, 10);
+
+    }
+
+    private void addWithDynamicCompiledClasses() throws IOException, IllegalAccessException, InstantiationException,
+      ResourceException, ScriptException, javax.script.ScriptException {
+        LOG.info("Invocation of a dynamic groovy script...");
+        addWithGroovyShell(5, 10);
+        LOG.info("Invocation of the run method of a dynamic groovy script...");
+        addWithGroovyShellRun();
+        LOG.info("Invocation of a dynamic groovy class loaded with GroovyClassLoader...");
+        addWithGroovyClassLoader(10, 30);
+        LOG.info("Invocation of a dynamic groovy class loaded with GroovyScriptEngine...");
+        addWithGroovyScriptEngine(15, 0);
+        LOG.info("Invocation of a dynamic groovy class loaded with GroovyScriptEngine JSR223...");
+        addWithEngineFactory(5, 6);
+    }
+
+    public static void main(String[] args) throws InstantiationException, IllegalAccessException,
+      ResourceException, ScriptException, IOException, javax.script.ScriptException {
+        MyJointCompilationApp myJointCompilationApp = new MyJointCompilationApp();
+        LOG.info("Example of addition operation via Groovy scripts integration with Java.");
+        myJointCompilationApp.addWithStaticCompiledClasses();
+        myJointCompilationApp.addWithDynamicCompiledClasses();
+    }
+}

core-groovy-2/src/test/groovy/com/baeldung/xml/MarkupBuilderUnitTest.groovy

@@ -0,0 +1,40 @@
+package com.baeldung.xml
+
+import groovy.xml.MarkupBuilder
+import groovy.xml.XmlUtil
+import spock.lang.Specification
+
+class MarkupBuilderUnitTest extends Specification {
+
+    def xmlFile = getClass().getResource("articles_short_formatted.xml")
+
+def "Should create XML properly"() {
+    given: "Node structures"
+
+    when: "Using MarkupBuilderUnitTest to create com.baeldung.xml structure"
+    def writer = new StringWriter()
+    new MarkupBuilder(writer).articles {
+        article {
+            title('First steps in Java')
+            author(id: '1') {
+                firstname('Siena')
+                lastname('Kerr')
+            }
+            'release-date'('2018-12-01')
+        }
+        article {
+            title('Dockerize your SpringBoot application')
+            author(id: '2') {
+                firstname('Jonas')
+                lastname('Lugo')
+            }
+            'release-date'('2018-12-01')
+        }
+    }
+
+    then: "Xml is created properly"
+    XmlUtil.serialize(writer.toString()) == XmlUtil.serialize(xmlFile.text)
+}
+
+
+}

core-groovy-2/src/test/groovy/com/baeldung/xml/XmlParserUnitTest.groovy

@@ -0,0 +1,94 @@
+package com.baeldung.xml
+
+
+import spock.lang.Shared
+import spock.lang.Specification
+
+class XmlParserUnitTest extends Specification {
+
+    def xmlFile = getClass().getResourceAsStream("articles.xml")
+
+    @Shared
+    def parser = new XmlParser()
+
+    def "Should read XML file properly"() {
+        given: "XML file"
+
+        when: "Using XmlParser to read file"
+        def articles = parser.parse(xmlFile)
+
+        then: "Xml is loaded properly"
+        articles.'*'.size() == 4
+        articles.article[0].author.firstname.text() == "Siena"
+        articles.article[2].'release-date'.text() == "2018-06-12"
+        articles.article[3].title.text() == "Java 12 insights"
+        articles.article.find { it.author.'@id'.text() == "3" }.author.firstname.text() == "Daniele"
+    }
+
+
+    def "Should add node to existing com.baeldung.xml using NodeBuilder"() {
+        given: "XML object"
+        def articles = parser.parse(xmlFile)
+
+        when: "Adding node to com.baeldung.xml"
+        def articleNode = new NodeBuilder().article(id: '5') {
+            title('Traversing XML in the nutshell')
+            author {
+                firstname('Martin')
+                lastname('Schmidt')
+            }
+            'release-date'('2019-05-18')
+        }
+        articles.append(articleNode)
+
+        then: "Node is added to com.baeldung.xml properly"
+        articles.'*'.size() == 5
+        articles.article[4].title.text() == "Traversing XML in the nutshell"
+    }
+
+    def "Should replace node"() {
+        given: "XML object"
+        def articles = parser.parse(xmlFile)
+
+        when: "Adding node to com.baeldung.xml"
+        def articleNode = new NodeBuilder().article(id: '5') {
+            title('Traversing XML in the nutshell')
+            author {
+                firstname('Martin')
+                lastname('Schmidt')
+            }
+            'release-date'('2019-05-18')
+        }
+        articles.article[0].replaceNode(articleNode)
+
+        then: "Node is added to com.baeldung.xml properly"
+        articles.'*'.size() == 4
+        articles.article[0].title.text() == "Traversing XML in the nutshell"
+    }
+
+    def "Should modify node"() {
+        given: "XML object"
+        def articles = parser.parse(xmlFile)
+
+        when: "Changing value of one of the nodes"
+        articles.article.each { it.'release-date'[0].value = "2019-05-18" }
+
+        then: "XML is updated"
+        articles.article.findAll { it.'release-date'.text() != "2019-05-18" }.isEmpty()
+    }
+
+    def "Should remove article from com.baeldung.xml"() {
+        given: "XML object"
+        def articles = parser.parse(xmlFile)
+
+        when: "Removing all articles but with id==3"
+        articles.article
+          .findAll { it.author.'@id'.text() != "3" }
+          .each { articles.remove(it) }
+
+        then: "There is only one article left"
+        articles.children().size() == 1
+        articles.article[0].author.'@id'.text() == "3"
+    }
+
+}

core-groovy-2/src/test/groovy/com/baeldung/xml/XmlSlurperUnitTest.groovy

@@ -0,0 +1,102 @@
+package com.baeldung.xml
+
+
+import groovy.xml.XmlUtil
+import spock.lang.Shared
+import spock.lang.Specification
+
+class XmlSlurperUnitTest extends Specification {
+
+    def xmlFile = getClass().getResourceAsStream("articles.xml")
+
+    @Shared
+    def parser = new XmlSlurper()
+
+    def "Should read XML file properly"() {
+        given: "XML file"
+
+        when: "Using XmlSlurper to read file"
+        def articles = parser.parse(xmlFile)
+
+        then: "Xml is loaded properly"
+        articles.'*'.size() == 4
+        articles.article[0].author.firstname == "Siena"
+        articles.article[2].'release-date' == "2018-06-12"
+        articles.article[3].title == "Java 12 insights"
+        articles.article.find { it.author.'@id' == "3" }.author.firstname == "Daniele"
+    }
+
+    def "Should add node to existing com.baeldung.xml"() {
+        given: "XML object"
+        def articles = parser.parse(xmlFile)
+
+        when: "Adding node to com.baeldung.xml"
+        articles.appendNode {
+            article(id: '5') {
+                title('Traversing XML in the nutshell')
+                author {
+                    firstname('Martin')
+                    lastname('Schmidt')
+                }
+                'release-date'('2019-05-18')
+            }
+        }
+
+        articles = parser.parseText(XmlUtil.serialize(articles))
+
+        then: "Node is added to com.baeldung.xml properly"
+        articles.'*'.size() == 5
+        articles.article[4].title == "Traversing XML in the nutshell"
+    }
+
+    def "Should modify node"() {
+        given: "XML object"
+        def articles = parser.parse(xmlFile)
+
+        when: "Changing value of one of the nodes"
+        articles.article.each { it.'release-date' = "2019-05-18" }
+
+        then: "XML is updated"
+        articles.article.findAll { it.'release-date' != "2019-05-18" }.isEmpty()
+    }
+
+    def "Should replace node"() {
+        given: "XML object"
+        def articles = parser.parse(xmlFile)
+
+        when: "Replacing node"
+        articles.article[0].replaceNode {
+            article(id: '5') {
+                title('Traversing XML in the nutshell')
+                author {
+                    firstname('Martin')
+                    lastname('Schmidt')
+                }
+                'release-date'('2019-05-18')
+            }
+        }
+
+        articles = parser.parseText(XmlUtil.serialize(articles))
+
+        then: "Node is replaced properly"
+        articles.'*'.size() == 4
+        articles.article[0].title == "Traversing XML in the nutshell"
+    }
+
+    def "Should remove article from com.baeldung.xml"() {
+        given: "XML object"
+        def articles = parser.parse(xmlFile)
+
+        when: "Removing all articles but with id==3"
+        articles.article
+          .findAll { it.author.'@id' != "3" }
+          .replaceNode {}
+
+        articles = parser.parseText(XmlUtil.serialize(articles))
+
+        then: "There is only one article left"
+        articles.children().size() == 1
+        articles.article[0].author.'@id' == "3"
+    }
+
+}

core-groovy-2/src/test/resources/com/baeldung/xml/articles.xml

@@ -0,0 +1,34 @@
+<articles>
+    <article>
+        <title>First steps in Java</title>
+        <author id='1'>
+            <firstname>Siena</firstname>
+            <lastname>Kerr</lastname>
+        </author>
+        <release-date>2018-12-01</release-date>
+    </article>
+    <article>
+        <title>Dockerize your SpringBoot application</title>
+        <author id='2'>
+            <firstname>Jonas</firstname>
+            <lastname>Lugo</lastname>
+        </author>
+        <release-date>2018-12-01</release-date>
+    </article>
+    <article>
+        <title>SpringBoot tutorial</title>
+        <author id='3'>
+            <firstname>Daniele</firstname>
+            <lastname>Ferguson</lastname>
+        </author>
+        <release-date>2018-06-12</release-date>
+    </article>
+    <article>
+        <title>Java 12 insights</title>
+        <author id='1'>
+            <firstname>Siena</firstname>
+            <lastname>Kerr</lastname>
+        </author>
+        <release-date>2018-07-22</release-date>
+    </article>
+</articles>

core-groovy-2/src/test/resources/com/baeldung/xml/articles_short_formatted.xml

@@ -0,0 +1,18 @@
+<articles>
+  <article>
+    <title>First steps in Java</title>
+    <author id='1'>
+      <firstname>Siena</firstname>
+      <lastname>Kerr</lastname>
+    </author>
+    <release-date>2018-12-01</release-date>
+  </article>
+  <article>
+    <title>Dockerize your SpringBoot application</title>
+    <author id='2'>
+      <firstname>Jonas</firstname>
+      <lastname>Lugo</lastname>
+    </author>
+    <release-date>2018-12-01</release-date>
+  </article>
+</articles>

core-java-lang/src/main/java/com/baeldung/error/ErrorGenerator.java

@@ -1,15 +0,0 @@
-package com.baeldung.error;
-
-public class ErrorGenerator {
-    public void throwException() throws Exception {
-        throw new Exception("checked");
-    }
-
-    public void throwRuntimeException() {
-        throw new RuntimeException("unchecked");
-    }
-
-    public void throwError() {
-        throw new Error("unchecked");
-    }
-}

core-java-lang/src/test/java/com/baeldung/error/ErrorGeneratorUnitTest.java

@@ -1,51 +0,0 @@
-package com.baeldung.error;
-
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
-
-public class ErrorGeneratorUnitTest {
-
-    private ErrorGenerator errorGenerator;
-
-    @Before
-    public void setUp() {
-        errorGenerator = new ErrorGenerator();
-    }
-
-    @Test
-    public void whenCheckedException_thenIsCaughtByCatchException() {
-        try {
-            errorGenerator.throwException();
-        } catch (Exception e) {
-            // caught! -> test pass
-        }
-    }
-
-    @Test
-    public void whenUncheckedException_thenIsCaughtByCatchException() {
-        try {
-            errorGenerator.throwRuntimeException();
-        } catch (Exception e) {
-            // caught! -> test pass
-        }
-    }
-
-    @Test(expected = Error.class)
-    public void whenError_thenIsNotCaughtByCatchException() {
-        try {
-            errorGenerator.throwError();
-        } catch (Exception e) {
-            Assert.fail(); // errors are not caught by catch exception
-        }
-    }
-
-    @Test
-    public void whenError_thenIsCaughtByCatchError() {
-        try {
-            errorGenerator.throwError();
-        } catch (Error e) {
-            // caught! -> test pass
-        }
-    }
-}

core-java-modules/README.md

@@ -1,3 +1,5 @@
 ## Relevant articles:
 
 - [Multi-Module Maven Application with Java Modules](https://www.baeldung.com/maven-multi-module-project-java-jpms)
+- [Guide to Java FileChannel](https://www.baeldung.com/java-filechannel)
+- [Understanding the NumberFormatException in Java](https://www.baeldung.com/java-number-format-exception)

core-java-modules/core-java-10/src/main/java/com/baeldung/set/CopySets.java

@@ -0,0 +1,13 @@
+package com.baeldung.set;
+
+import java.util.Set;
+
+public class CopySets {
+
+    // Using Java 10
+    public static <T> Set<T> copyBySetCopyOf(Set<T> original) {
+        Set<T> copy = Set.copyOf(original);
+        return copy;
+    }
+
+}

core-java-modules/core-java-11/README.md

@@ -7,4 +7,5 @@
 - [Exploring the New HTTP Client in Java 9 and 11](https://www.baeldung.com/java-9-http-client)
 - [An Introduction to Epsilon GC: A No-Op Experimental Garbage Collector](https://www.baeldung.com/jvm-epsilon-gc-garbage-collector)
 - [Guide to jlink](https://www.baeldung.com/jlink)
+- [Negate a Predicate Method Reference with Java 11](https://www.baeldung.com/java-negate-predicate-method-reference)
 - [Transforming an Empty String into an Empty Optional](https://www.baeldung.com/java-empty-string-to-empty-optional)

core-java-modules/core-java-8-2/README.md

@@ -3,5 +3,6 @@
 ## Core Java 8 Cookbooks and Examples (part 2)
 
 ### Relevant Articles: 
-- [Anonymous Classes in Java](https://www.baeldung.com/java-anonymous-classes)
+- [Anonymous Classes in Java](http://www.baeldung.com/)
+- [How to Delay Code Execution in Java](https://www.baeldung.com/java-delay-code-execution)
 - [Run JAR Application With Command Line Arguments](https://www.baeldung.com/java-run-jar-with-arguments)

core-java-modules/core-java-8-2/pom.xml

@@ -30,7 +30,6 @@
             <artifactId>icu4j</artifactId>
             <version>${icu.version}</version>
         </dependency>
-
     </dependencies>
 
     <build>

core-java-modules/core-java-8-2/src/main/resources/META-INF/persistence.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<persistence xmlns="http://java.sun.com/xml/ns/persistence"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
+	version="2.0">
+
+	<persistence-unit
+		name="com.baeldung.optionalReturnType"
+		transaction-type="RESOURCE_LOCAL">
+		<description>Persist Optional Return Type Demo</description>
+		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+		<class>com.baeldung.optionalReturnType.User</class>
+		<class>com.baeldung.optionalReturnType.UserOptional</class>
+		<!-- 
+		<class>com.baeldung.optionalReturnType.UserOptionalField</class>
+		-->
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+
+		<properties>
+			<property name="javax.persistence.jdbc.driver"
+				value="org.h2.Driver" />
+			<property name="javax.persistence.jdbc.url"
+				value="jdbc:h2:mem:test" />
+			<property name="javax.persistence.jdbc.user" value="sa" />
+			<property name="javax.persistence.jdbc.password" value="" />
+			<property name="hibernate.dialect"
+				value="org.hibernate.dialect.H2Dialect" />
+			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
+			<property name="show_sql" value="true" />
+			<property name="hibernate.temp.use_jdbc_metadata_defaults"
+				value="false" />
+		</properties>
+	</persistence-unit>
+</persistence>

core-java-modules/core-java-9/README.md

@@ -28,6 +28,6 @@
 - [Java 9 Convenience Factory Methods for Collections](https://www.baeldung.com/java-9-collections-factory-methods)
 - [Java 9 Stream API Improvements](https://www.baeldung.com/java-9-stream-api)
 - [A Guide to Java 9 Modularity](https://www.baeldung.com/java-9-modularity)
-- [Java 9 Platform Module API](https://www.baeldung.com/java-9-module-api)
+- [Java 9 java.lang.Module API](https://www.baeldung.com/java-9-module-api)
 - [Java 9 Platform Logging API](https://www.baeldung.com/java-9-logging-api)
 - [Filtering a Stream of Optionals in Java](https://www.baeldung.com/java-filter-stream-of-optional)

core-java-modules/core-java-9/src/modules/com.baeldung.logging.slf4j/com/baeldung/logging/slf4j/Slf4jLogger.java

@@ -75,7 +75,7 @@ public class Slf4jLogger implements System.Logger {
         if (!isLoggable(level)) {
             return;
         }
-        String message = MessageFormat.format (format, params);
+        String message = MessageFormat.format(format, params);
 
         switch (level) {
         case TRACE:

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

@@ -15,3 +15,4 @@
 - [Intersection Between two Integer Arrays](https://www.baeldung.com/java-array-intersection)
 - [Sorting Arrays in Java](https://www.baeldung.com/java-sorting-arrays)
 - [Convert a Float to a Byte Array in Java](https://www.baeldung.com/java-convert-float-to-byte-array)
+- [Converting Between Stream and Array in Java](https://www.baeldung.com/java-stream-to-array)

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

@@ -24,10 +24,20 @@
         <artifactId>commons-collections4</artifactId>
         <version>${commons-collections4.version}</version>
     </dependency>
+    <dependency>
+        <groupId>com.google.code.gson</groupId>
+        <artifactId>gson</artifactId>
+        <version>2.8.5</version>
+    </dependency>
+    <dependency>
+        <groupId>commons-lang</groupId>
+        <artifactId>commons-lang</artifactId>
+        <version>2.6</version>
+    </dependency>
     </dependencies>
 
     <properties>
         <commons-collections4.version>4.3</commons-collections4.version>
         <guava.version>27.1-jre</guava.version>
     </properties>
-</project>
+</project>

core-java-modules/core-java-collections-set/src/main/java/com/baeldung/set/CopySets.java

@@ -0,0 +1,59 @@
+package com.baeldung.set;
+
+import java.io.Serializable;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.apache.commons.lang.SerializationUtils;
+
+import com.google.gson.Gson;
+
+public class CopySets {
+
+    // Copy Constructor
+    public static <T> Set<T> copyByConstructor(Set<T> original) {
+        Set<T> copy = new HashSet<>(original);
+        return copy;
+    }
+
+    // Set.addAll
+    public static <T> Set<T> copyBySetAddAll(Set<T> original) {
+        Set<T> copy = new HashSet<>();
+        copy.addAll(original);
+        return copy;
+    }
+
+    // Set.clone
+    public static <T> Set<T> copyBySetClone(HashSet<T> original) {
+        Set<T> copy = (Set<T>) original.clone();
+        return copy;
+    }
+
+    // JSON
+    public static <T> Set<T> copyByJson(Set<T> original) {
+        Gson gson = new Gson();
+        String jsonStr = gson.toJson(original);
+        Set<T> copy = gson.fromJson(jsonStr, Set.class);
+
+        return copy;
+    }
+
+    // Apache Commons Lang
+    public static <T extends Serializable> Set<T> copyByApacheCommonsLang(Set<T> original) {
+        Set<T> copy = new HashSet<>();
+        for (T item : original) {
+            copy.add((T) SerializationUtils.clone(item));
+        }
+        return copy;
+    }
+
+    // Collectors.toSet
+    public static <T extends Serializable> Set<T> copyByCollectorsToSet(Set<T> original) {
+        Set<T> copy = original.stream()
+            .collect(Collectors.toSet());
+
+        return copy;
+    }
+
+}