Kap. 4

src/pp.04.01-RunnableReturn/justfile

@@ -0,0 +1,12 @@
+default:
+    mvn clean compile exec:java
+exec args:
+    mvn exec:java -Dexec.args={{args}}
+clean:
+    mvn clean
+compile:
+    mvn compile
+test:
+    mvn test
+javadoc:
+    mvn javadoc:javadoc

src/pp.04.01-RunnableReturn/pom.xml

@@ -0,0 +1,61 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>pp</groupId>
+  <artifactId>pp.04.01-RunnableReturn</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <properties>	
+    <exec.mainClass>pp.Main</exec.mainClass>
+    <maven.compiler.release>10</maven.compiler.release>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+  <dependencies>
+    <dependency><!-- für Unit-Tests -->
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.10.0</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency><!-- für Lombok -->
+      <groupId>org.projectlombok</groupId>
+      <artifactId>lombok</artifactId>
+      <version>1.18.30</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency><!-- für net.jcip Annotationen -->
+      <groupId>net.jcip</groupId>
+      <artifactId>jcip-annotations</artifactId>
+      <version>1.0</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin><!-- für Unit-Tests [mvn test] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>3.0.0</version>
+      </plugin>
+      <plugin><!-- [mvn compile] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.9.0</version>
+      </plugin>
+      <plugin><!-- [mvn exec:java] -->
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>3.1.0</version>
+      </plugin>
+      <plugin><!-- [mvn javadoc:javadoc] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <version>3.5.0</version>
+        <configuration>
+          <show>private</show>
+          <locale>en_US</locale>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/pp.04.01-RunnableReturn/src/main/java/pp/Expression.java

@@ -0,0 +1,6 @@
+package pp;
+
+@FunctionalInterface
+public interface Expression<T> {
+    public T eval();
+}

src/pp.04.01-RunnableReturn/src/main/java/pp/Main.java

@@ -0,0 +1,9 @@
+package pp;
+
+public class Main {
+
+    public static void main(String... args) throws InterruptedException {
+        // hier programmieren
+    }
+
+}

src/pp.04.01-RunnableReturn/src/main/java/pp/RunnableWithResult.java

@@ -0,0 +1,28 @@
+package pp;
+
+public class RunnableWithResult<T> implements Runnable {
+    private final Expression<T> expr;
+
+    public RunnableWithResult(Expression<T> expr) {
+        this.expr = expr;
+    }
+
+    @Override
+    public void run() {
+        // hier programmieren
+    }
+
+    public synchronized Boolean isAvailable() {
+        // hier programmieren
+        return null;
+    }
+
+    public synchronized T get() {
+        // hier programmieren
+        return null;
+    }
+
+    public Expression<T> expr() {
+        return expr;
+    }
+}

src/pp.04.01-RunnableReturn_solution/justfile

@@ -0,0 +1,12 @@
+default:
+    mvn clean compile exec:java
+exec args:
+    mvn exec:java -Dexec.args={{args}}
+clean:
+    mvn clean
+compile:
+    mvn compile
+test:
+    mvn test
+javadoc:
+    mvn javadoc:javadoc

src/pp.04.01-RunnableReturn_solution/pom.xml

@@ -0,0 +1,61 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>pp</groupId>
+  <artifactId>pp.04.01-RunnableReturn_solution</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <properties>	
+    <exec.mainClass>pp.Main</exec.mainClass>
+    <maven.compiler.release>10</maven.compiler.release>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+  <dependencies>
+    <dependency><!-- für Unit-Tests -->
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.10.0</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency><!-- für Lombok -->
+      <groupId>org.projectlombok</groupId>
+      <artifactId>lombok</artifactId>
+      <version>1.18.30</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency><!-- für net.jcip Annotationen -->
+      <groupId>net.jcip</groupId>
+      <artifactId>jcip-annotations</artifactId>
+      <version>1.0</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin><!-- für Unit-Tests [mvn test] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>3.0.0</version>
+      </plugin>
+      <plugin><!-- [mvn compile] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.9.0</version>
+      </plugin>
+      <plugin><!-- [mvn exec:java] -->
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>3.1.0</version>
+      </plugin>
+      <plugin><!-- [mvn javadoc:javadoc] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <version>3.5.0</version>
+        <configuration>
+          <show>private</show>
+          <locale>en_US</locale>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/pp.04.01-RunnableReturn_solution/src/main/java/pp/Expression.java

@@ -0,0 +1,6 @@
+package pp;
+
+@FunctionalInterface
+public interface Expression<T> {
+    public T eval();
+}

src/pp.04.01-RunnableReturn_solution/src/main/java/pp/Main.java

@@ -0,0 +1,35 @@
+package pp;
+
+public class Main {
+
+    public static void main(String... args) throws InterruptedException {
+        var r1 = new RunnableWithResult2<>(() -> {
+            try {
+                Thread.sleep(3000);
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            }
+            return 1 + 2;
+        });
+        var r2 = new RunnableWithResult2<>(() -> 3 + 4);
+        var r3 = new RunnableWithResult2<>(() -> {
+            while (!r1.isAvailable() || !r2.isAvailable()) {
+                System.out.println("waiting on r1 or r2");
+            }
+            return r1.get() + r2.get();
+        });
+
+        var thread1 = new Thread(r1);
+        var thread2 = new Thread(r2);
+        var thread3 = new Thread(r3);
+
+        thread1.start();
+        thread2.start();
+        thread3.start();
+
+        while (!r3.isAvailable()) {
+            System.out.println("waiting on r3");
+        }
+        System.out.println("result: " + r3.get());
+    }
+}

src/pp.04.01-RunnableReturn_solution/src/main/java/pp/RunnableWithResult.java

@@ -0,0 +1,28 @@
+package pp;
+
+public class RunnableWithResult<T> implements Runnable {
+    private final Expression<T> expr;
+
+    public RunnableWithResult(Expression<T> expr) {
+        this.expr = expr;
+    }
+
+    @Override
+    public void run() {
+        // hier programmieren
+    }
+
+    public synchronized Boolean isAvailable() {
+        // hier programmieren
+        return null;
+    }
+
+    public synchronized T get() {
+        // hier programmieren
+        return null;
+    }
+
+    public Expression<T> expr() {
+        return expr;
+    }
+}

src/pp.04.01-RunnableReturn_solution/src/main/java/pp/RunnableWithResult1.java

@@ -0,0 +1,31 @@
+package pp;
+
+public class RunnableWithResult1<T> extends RunnableWithResult<T> {
+    private T result;
+    private boolean finished;
+
+    public RunnableWithResult1(Expression<T> expr) {
+        super(expr);
+    }
+
+    @Override
+    public void run() {
+        synchronized (this) { // Memorybarrier
+            this.finished = false;
+        }
+        this.result = expr().eval();
+        synchronized (this) {
+            this.finished = true;
+        } // Memorybarrier
+    }
+
+    @Override
+    public synchronized Boolean isAvailable() {
+        return this.finished;
+    }
+
+    @Override
+    public synchronized T get() {
+        return this.result;
+    }
+}

src/pp.04.01-RunnableReturn_solution/src/main/java/pp/RunnableWithResult2.java

@@ -0,0 +1,26 @@
+package pp;
+
+public class RunnableWithResult2<T> extends RunnableWithResult<T> {
+    private T result;
+    private volatile Thread self;
+
+    public RunnableWithResult2(Expression<T> expr) {
+        super(expr);
+    }
+
+    @Override
+    public void run() {
+        this.self = Thread.currentThread();
+        this.result = expr().eval();
+    }
+
+    @Override
+    public synchronized Boolean isAvailable() {
+        return (this.self != null) && !this.self.isAlive();
+    }
+
+    @Override
+    public synchronized T get() {
+        return this.result;
+    }
+}

src/pp.04.01-RunnableReturn_solution/src/main/java/pp/RunnableWithResult3.java

@@ -0,0 +1,27 @@
+package pp;
+
+public class RunnableWithResult3<T> extends RunnableWithResult<T> {
+    private T result;
+    private Thread executor;
+
+    public RunnableWithResult3(Expression<T> expr) {
+        super(expr);
+        this.executor = new Thread(this);
+        this.executor.start();
+    }
+
+    @Override
+    public void run() {
+        this.result = expr().eval();
+    }
+
+    @Override
+    public synchronized Boolean isAvailable() {
+        return (this.executor != null) && !this.executor.isAlive();
+    }
+
+    @Override
+    public synchronized T get() {
+        return this.result;
+    }
+}

src/pp.04.02-Future/justfile

@@ -0,0 +1,12 @@
+default:
+    mvn clean compile exec:java
+exec args:
+    mvn exec:java -Dexec.args={{args}}
+clean:
+    mvn clean
+compile:
+    mvn compile
+test:
+    mvn test
+javadoc:
+    mvn javadoc:javadoc

src/pp.04.02-Future/pom.xml

@@ -0,0 +1,61 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>pp</groupId>
+  <artifactId>pp.04.02-Future</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <properties>	
+    <exec.mainClass>pp.Main</exec.mainClass>
+    <maven.compiler.release>10</maven.compiler.release>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+  <dependencies>
+    <dependency><!-- für Unit-Tests -->
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.10.0</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency><!-- für Lombok -->
+      <groupId>org.projectlombok</groupId>
+      <artifactId>lombok</artifactId>
+      <version>1.18.30</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency><!-- für net.jcip Annotationen -->
+      <groupId>net.jcip</groupId>
+      <artifactId>jcip-annotations</artifactId>
+      <version>1.0</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin><!-- für Unit-Tests [mvn test] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>3.0.0</version>
+      </plugin>
+      <plugin><!-- [mvn compile] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.9.0</version>
+      </plugin>
+      <plugin><!-- [mvn exec:java] -->
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>3.1.0</version>
+      </plugin>
+      <plugin><!-- [mvn javadoc:javadoc] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <version>3.5.0</version>
+        <configuration>
+          <show>private</show>
+          <locale>en_US</locale>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/pp.04.02-Future/src/main/java/pp/Main.java

@@ -0,0 +1,13 @@
+package pp;
+
+import java.util.concurrent.Executors;
+
+public class Main {
+
+    public static void main(String... args) {
+        var executor = Executors.newCachedThreadPool();
+        // hier programmieren
+        executor.shutdown();
+    }
+
+}

src/pp.04.02-Future_solution/justfile

@@ -0,0 +1,12 @@
+default:
+    mvn clean compile exec:java
+exec args:
+    mvn exec:java -Dexec.args={{args}}
+clean:
+    mvn clean
+compile:
+    mvn compile
+test:
+    mvn test
+javadoc:
+    mvn javadoc:javadoc

src/pp.04.02-Future_solution/pom.xml

@@ -0,0 +1,61 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>pp</groupId>
+  <artifactId>pp.04.02-Future_solution</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <properties>	
+    <exec.mainClass>pp.Main</exec.mainClass>
+    <maven.compiler.release>10</maven.compiler.release>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+  <dependencies>
+    <dependency><!-- für Unit-Tests -->
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.10.0</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency><!-- für Lombok -->
+      <groupId>org.projectlombok</groupId>
+      <artifactId>lombok</artifactId>
+      <version>1.18.30</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency><!-- für net.jcip Annotationen -->
+      <groupId>net.jcip</groupId>
+      <artifactId>jcip-annotations</artifactId>
+      <version>1.0</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin><!-- für Unit-Tests [mvn test] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>3.0.0</version>
+      </plugin>
+      <plugin><!-- [mvn compile] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.9.0</version>
+      </plugin>
+      <plugin><!-- [mvn exec:java] -->
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>3.1.0</version>
+      </plugin>
+      <plugin><!-- [mvn javadoc:javadoc] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <version>3.5.0</version>
+        <configuration>
+          <show>private</show>
+          <locale>en_US</locale>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/pp.04.02-Future_solution/src/main/java/pp/Main.java

@@ -0,0 +1,34 @@
+package pp;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executors;
+
+public class Main {
+
+    public static void main(String... args) {
+        var executor = Executors.newCachedThreadPool();
+        // Lambda-Ausdruck, mehrere Statements, explizites return
+        var f1 = executor.submit(() -> {
+            return 1.0 + 2.0;
+        });
+        // Callable als Inner Class
+        var f2 = executor.submit(new Callable<Double>() {
+            @Override
+            public Double call() throws Exception {
+                return 3.0 + 4.0;
+            }
+        });
+        // Lambda-Ausdruck, knapp
+        var f3 = executor.submit(() -> f1.get() + f2.get());
+        try {
+            // get() blockiert, bis etwas vorliegt (auch oben)
+            System.out.println(f3.get());
+        } catch (InterruptedException | ExecutionException e) {
+            // Exceptions in f1 und f2 werden bis zum f3.get() verzögert
+            Thread.currentThread().interrupt();
+        } finally {
+            executor.shutdown();
+        }
+    }
+}

src/pp.04.03-ThreadPoolSize/justfile

@@ -0,0 +1,12 @@
+default:
+    mvn clean compile exec:java
+exec args:
+    mvn exec:java -Dexec.args={{args}}
+clean:
+    mvn clean
+compile:
+    mvn compile
+test:
+    mvn test
+javadoc:
+    mvn javadoc:javadoc

src/pp.04.03-ThreadPoolSize/pom.xml

@@ -0,0 +1,61 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>pp</groupId>
+  <artifactId>pp.04.03-ThreadPoolSize</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <properties>	
+    <exec.mainClass>pp.Task</exec.mainClass>
+    <maven.compiler.release>10</maven.compiler.release>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+  <dependencies>
+    <dependency><!-- für Unit-Tests -->
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.10.0</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency><!-- für Lombok -->
+      <groupId>org.projectlombok</groupId>
+      <artifactId>lombok</artifactId>
+      <version>1.18.30</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency><!-- für net.jcip Annotationen -->
+      <groupId>net.jcip</groupId>
+      <artifactId>jcip-annotations</artifactId>
+      <version>1.0</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin><!-- für Unit-Tests [mvn test] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>3.0.0</version>
+      </plugin>
+      <plugin><!-- [mvn compile] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.9.0</version>
+      </plugin>
+      <plugin><!-- [mvn exec:java] -->
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>3.1.0</version>
+      </plugin>
+      <plugin><!-- [mvn javadoc:javadoc] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <version>3.5.0</version>
+        <configuration>
+          <show>private</show>
+          <locale>en_US</locale>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/pp.04.03-ThreadPoolSize/src/main/java/pp/CachedRunner.java

@@ -0,0 +1,16 @@
+package pp;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class CachedRunner {
+
+    public static ExecutorService test(Runnable task, int tries) {
+        var pool = Executors.newCachedThreadPool();
+        for (var i = 1; i <= tries; i++) {
+            pool.execute(task);
+        }
+        return pool;
+    }
+
+}

src/pp.04.03-ThreadPoolSize/src/main/java/pp/FixedRunner.java

@@ -0,0 +1,17 @@
+package pp;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class FixedRunner {
+    private final static int SIZE = 6;
+
+    public static ExecutorService test(Runnable task, int tries) {
+        var pool = Executors.newFixedThreadPool(SIZE);
+        for (var i = 1; i <= tries; i++) {
+            pool.execute(task);
+        }
+        return pool;
+    }
+
+}

src/pp.04.03-ThreadPoolSize/src/main/java/pp/Task.java

@@ -0,0 +1,17 @@
+package pp;
+
+public class Task implements Runnable {
+
+    private static final int NUMBER_OF_TASKS = 1;
+
+    @Override
+    public void run() {
+        // TODO
+    }
+
+    public static void main(String... args) {
+        // var pool = CachedRunner.test(new Task(), NUMBER_OF_TASKS);
+        var pool = FixedRunner.test(new Task(), NUMBER_OF_TASKS);
+    }
+
+}

src/pp.04.03-ThreadPoolSize_solution/justfile

@@ -0,0 +1,20 @@
+default:
+    mvn clean compile exec:java
+
+innerClass: (_exec "pp.TaskInnerClass" "")
+lambda: (_exec "pp.TaskLambda" "")
+staticClass: (_exec "pp.TaskStaticClass" "")
+
+_exec class args:
+    mvn exec:java -Dexec.mainClass={{class}} -Dexec.args={{args}}
+
+exec args:
+    mvn exec:java -Dexec.args={{args}}
+clean:
+    mvn clean
+compile:
+    mvn compile
+test:
+    mvn test
+javadoc:
+    mvn javadoc:javadoc

src/pp.04.03-ThreadPoolSize_solution/pom.xml

@@ -0,0 +1,61 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>pp</groupId>
+  <artifactId>pp.04.03-ThreadPoolSize_solution</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <properties>	
+    <exec.mainClass>pp.TaskLambda</exec.mainClass>
+    <maven.compiler.release>10</maven.compiler.release>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+  <dependencies>
+    <dependency><!-- für Unit-Tests -->
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.10.0</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency><!-- für Lombok -->
+      <groupId>org.projectlombok</groupId>
+      <artifactId>lombok</artifactId>
+      <version>1.18.30</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency><!-- für net.jcip Annotationen -->
+      <groupId>net.jcip</groupId>
+      <artifactId>jcip-annotations</artifactId>
+      <version>1.0</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin><!-- für Unit-Tests [mvn test] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>3.0.0</version>
+      </plugin>
+      <plugin><!-- [mvn compile] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.9.0</version>
+      </plugin>
+      <plugin><!-- [mvn exec:java] -->
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>3.1.0</version>
+      </plugin>
+      <plugin><!-- [mvn javadoc:javadoc] -->
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <version>3.5.0</version>
+        <configuration>
+          <show>private</show>
+          <locale>en_US</locale>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/pp.04.03-ThreadPoolSize_solution/src/main/java/pp/CachedRunner.java

@@ -0,0 +1,16 @@
+package pp;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class CachedRunner {
+
+    public static ExecutorService test(Runnable task, int tries) {
+        var pool = Executors.newCachedThreadPool();
+        for (var i = 1; i <= tries; i++) {
+            pool.execute(task);
+        }
+        return pool;
+    }
+
+}

src/pp.04.03-ThreadPoolSize_solution/src/main/java/pp/FixedRunner.java

@@ -0,0 +1,17 @@
+package pp;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class FixedRunner {
+    private final static int SIZE = 6;
+
+    public static ExecutorService test(Runnable task, int tries) {
+        var pool = Executors.newFixedThreadPool(SIZE);
+        for (var i = 1; i <= tries; i++) {
+            pool.execute(task);
+        }
+        return pool;
+    }
+
+}

src/pp.04.03-ThreadPoolSize_solution/src/main/java/pp/TaskInnerClass.java

@@ -0,0 +1,34 @@
+package pp;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+public class TaskInnerClass {
+
+    private static final int NUMBER_OF_TASKS = 20;
+
+    public static void main(String... args) {
+        var pool1 = FixedRunner.test(new Runnable() {
+            @Override
+            public void run() {
+                System.out.println(Thread.currentThread().getName());
+            }
+        }, NUMBER_OF_TASKS);
+        var pool2 = CachedRunner.test(new Runnable() {
+            @Override
+            public void run() {
+                System.out.println(Thread.currentThread().getName());
+            }
+        }, NUMBER_OF_TASKS);
+        var scheduler = Executors.newSingleThreadScheduledExecutor();
+        scheduler.schedule(new Runnable() {
+            @Override
+            public void run() {
+                pool1.shutdown();
+                pool2.shutdown();
+                scheduler.shutdown();
+            }
+        }, 5, TimeUnit.SECONDS);
+    }
+
+}

src/pp.04.03-ThreadPoolSize_solution/src/main/java/pp/TaskLambda.java

@@ -0,0 +1,24 @@
+package pp;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+public class TaskLambda {
+
+    private static final int NUMBER_OF_TASKS = 20;
+
+    public static void main(String... args) {
+        var pool1 = FixedRunner.test(
+                () -> System.out.println(Thread.currentThread().getName()),
+                NUMBER_OF_TASKS);
+        var pool2 = CachedRunner.test(
+                () -> System.out.println(Thread.currentThread().getName()),
+                NUMBER_OF_TASKS);
+        var scheduler = Executors.newSingleThreadScheduledExecutor();
+        scheduler.schedule(() -> {
+            pool1.shutdown();
+            pool2.shutdown();
+            scheduler.shutdown();
+        }, 5, TimeUnit.SECONDS);
+    }
+}

src/pp.04.03-ThreadPoolSize_solution/src/main/java/pp/TaskStaticClass.java

@@ -0,0 +1,37 @@
+package pp;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+public class TaskStaticClass implements Runnable {
+    static class Shutdowner implements Runnable {
+        @Override
+        public void run() {
+            pool1.shutdown();
+            pool2.shutdown();
+            scheduler.shutdown();
+        }
+    }
+
+    private static final int NUMBER_OF_TASKS = 20;
+    private static ExecutorService pool1;
+    private static ExecutorService pool2;
+    private static ScheduledExecutorService scheduler;
+
+    @Override
+    public void run() {
+        System.out.println(Thread.currentThread().getName());
+    }
+
+    public static void main(String... args) {
+        pool1 = FixedRunner.test(new TaskStaticClass(),
+                NUMBER_OF_TASKS);
+        pool2 = CachedRunner.test(new TaskStaticClass(),
+                NUMBER_OF_TASKS);
+        scheduler = Executors.newSingleThreadScheduledExecutor();
+        scheduler.schedule(new Shutdowner(), 5, TimeUnit.SECONDS);
+    }
+
+}