herje

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.02.03-Lock</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <properties>
+        <exec.mainClass>pp.Factory</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/src/pp/Factory.java

@@ -0,0 +1,32 @@
+package pp;
+
+public class Factory {
+
+    private static Type instance;
+    private static Object lock = new Object();
+
+    public static Type getInstance() {
+        Type.prepare();
+        if (instance == null) {
+            instance = new Type();
+        }
+        return instance;
+    }
+
+    public static void main(String... args) throws InterruptedException {
+        var now = System.currentTimeMillis();
+        var threads = new Thread[100];
+        for (var i = 0; i < 100; i++) {
+            threads[i] = new Thread(() -> {
+                Type object = Factory.getInstance();
+                System.out.println(Thread.currentThread().getName() + ": serial of instance = " + object.getSerial());
+            }, String.format("InstanceGrabber-%02d", i));
+            threads[i].start();
+        }
+        for (var i = 0; i < 100; i++) {
+            threads[i].join();
+        }
+        var time = System.currentTimeMillis() - now;
+        System.out.println("Dauer: " + time + "ms");
+    }
+}

src/src/pp/Type.java

@@ -0,0 +1,38 @@
+package pp;
+
+import net.jcip.annotations.*;
+
+@ThreadSafe
+public final class Type {
+    //TODO Vlt Ordner Struktur Problem von Maven src/main/java/pp
+    private static int counter = 0;
+    private int serial = 0;
+    private int number = 0;
+
+    public static void prepare() {
+        try {
+            Thread.sleep(500);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
+    }
+
+    public Type() {
+        synchronized (Type.class) {
+            Type.counter++;
+            this.serial = Type.counter;
+        }
+    }
+
+    public synchronized int getNumber() {
+        return this.number;
+    }
+
+    public synchronized void setNumber(int number) {
+        this.number = number;
+    }
+
+    public synchronized int getSerial() {
+        return this.serial;
+    }
+}