Add a code snippet for anonymous classes (BAEL-2833) (#6690)

* Add a code snippet about anonymous classes (BAEL-2833)

Add a code snippet about anonymous classes (BAEL-2833)
Create module core-java-2 and move 'anonymous' package there

* Adjust the pom of core-java-8-2 module

* Adjust unit test

core-java-8-2/README.md

@@ -0,0 +1,6 @@
+=========
+
+## Core Java 8 Cookbooks and Examples (part 2)
+
+### Relevant Articles: 
+- [Anonymous Classes in Java](http://www.baeldung.com/)

core-java-8-2/pom.xml

@@ -0,0 +1,43 @@
+<?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>core-java-8-2</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-8-2</name>
+    <packaging>jar</packaging>
+
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-java</relativePath>
+    </parent>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+
+    <dependencies>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+
+    </build>
+</project>

core-java-8-2/src/main/java/com/baeldung/anonymous/Book.java

@@ -0,0 +1,15 @@
+package com.baeldung.anonymous;
+
+public class Book {
+
+    final String title;
+    
+    public Book(String title) {
+        this.title = title;
+    }
+    
+    public String description() {
+        return "Title: " + title;
+    }
+
+}

core-java-8-2/src/main/java/com/baeldung/anonymous/Main.java

@@ -0,0 +1,64 @@
+package com.baeldung.anonymous;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Code snippet that illustrates the usage of anonymous classes.
+ * 
+ * Note that use of Runnable instances in this example does not demonstrate their
+ * common use.
+ * 
+ * @author A. Shcherbakov
+ *
+ */
+public class Main {
+
+    public static void main(String[] args) {
+        final List<Runnable> actions = new ArrayList<Runnable>(2);
+
+        Runnable action = new Runnable() {
+            @Override
+            public void run() {
+                System.out.println("Hello from runnable.");
+            }
+
+        };
+        actions.add(action);
+
+        Book book = new Book("Design Patterns") {
+            @Override
+            public String description() {
+                return "Famous GoF book.";
+            }
+        };
+
+        System.out.println(String.format("Title: %s, description: %s", book.title, book.description()));
+
+        actions.add(new Runnable() {
+            @Override
+            public void run() {
+                System.out.println("Hello from runnable #2.");
+
+            }
+        });
+
+        int count = 1;
+
+        Runnable action2 = new Runnable() {
+            static final int x = 0;
+            // static int y = 0;
+
+            @Override
+            public void run() {
+                System.out.println(String.format("Runnable with captured variables: count = %s, x = %s", count, x));
+            }
+        };
+        actions.add(action2);
+
+        for (Runnable a : actions) {
+            a.run();
+        }
+    }
+
+}

core-java-8-2/src/test/java/com/baeldung/UnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+/**
+ * Unit test for simple App.
+ */
+public class UnitTest {
+    /**
+     * Stub test
+     */
+    @Test
+    public void givenPreconditions_whenCondition_shouldResult() {
+        assertTrue(true);
+    }
+}

pom.xml

@@ -380,6 +380,7 @@
                 <!-- <module>core-java-11</module> --> <!-- We haven't upgraded to java 11. Fixing in BAEL-10841 --> 
                 <!-- <module>core-java-12</module> --> <!-- We haven't upgraded to java 12. Fixing in BAEL-10841 -->
                 <module>core-java-8</module>
+                <module>core-java-8-2</module>
                 <!--<module>core-java-9</module> --> <!-- We haven't upgraded to java 9. Fixing in BAEL-10841 -->
                 <!--<module>core-java-os</module> --> <!-- We haven't upgraded to java 9.-->
                 <module>core-java-arrays</module>
@@ -1035,6 +1036,7 @@
                 <!-- <module>core-java-10</module> --> <!-- We haven't upgraded to java 10. Fixing in BAEL-10841 -->
                 <!-- <module>core-java-11</module> --> <!-- We haven't upgraded to java 11. Fixing in BAEL-10841 --> 
                 <module>core-java-8</module>
+                <module>core-java-8-2</module>
                 <!--<module>core-java-9</module> --> <!-- We haven't upgraded to java 9. Fixing in BAEL-10841 -->
                 <!--<module>core-java-os</module> --> <!-- We haven't upgraded to java 9.-->
                 <module>core-java-arrays</module>