Code example: Using a Mutex Object in Java (#7587)

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGenerator.java

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+package com.baeldung.concurrent.mutex;
+
+public class SequenceGenerator {
+    private int currentValue = 0;
+
+    public int getNextSequence() throws InterruptedException {
+        currentValue = currentValue + 1;
+        Thread.sleep(500);
+        return currentValue;
+    }
+}

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingMonitor.java

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+package com.baeldung.concurrent.mutex;
+
+import com.google.common.util.concurrent.Monitor;
+
+public class SequenceGeneratorUsingMonitor extends SequenceGenerator {
+
+    private Monitor monitor = new Monitor();
+
+    @Override
+    public int getNextSequence() throws InterruptedException {
+        monitor.enter();
+        try {
+            return super.getNextSequence();
+        } finally {
+            monitor.leave();
+        }
+    }
+}

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingReentrantLock.java

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+package com.baeldung.concurrent.mutex;
+
+import java.util.concurrent.locks.ReentrantLock;
+
+public class SequenceGeneratorUsingReentrantLock extends SequenceGenerator {
+
+    private ReentrantLock mutex = new ReentrantLock();
+
+    @Override
+    public int getNextSequence() throws InterruptedException {
+        try {
+            mutex.lock();
+            return super.getNextSequence();
+        } finally {
+            mutex.unlock();
+        }
+    }
+}

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSemaphore.java

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+package com.baeldung.concurrent.mutex;
+
+import java.util.concurrent.Semaphore;
+
+public class SequenceGeneratorUsingSemaphore extends SequenceGenerator {
+
+    private Semaphore mutex = new Semaphore(1);
+
+    @Override
+    public int getNextSequence() throws InterruptedException {
+        try {
+            mutex.acquire();
+            return super.getNextSequence();
+        } finally {
+            mutex.release();
+        }
+    }
+}

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSynchronizedBlock.java

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+package com.baeldung.concurrent.mutex;
+
+public class SequenceGeneratorUsingSynchronizedBlock extends SequenceGenerator {
+
+    @Override
+    public int getNextSequence() throws InterruptedException {
+        synchronized (this) {
+            return super.getNextSequence();
+        }
+    }
+
+}

core-java-modules/core-java-concurrency-basic/src/main/java/com/baeldung/concurrent/mutex/SequenceGeneratorUsingSynchronizedMethod.java

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+package com.baeldung.concurrent.mutex;
+
+public class SequenceGeneratorUsingSynchronizedMethod extends SequenceGenerator {
+
+    @Override
+    public synchronized int getNextSequence() throws InterruptedException {
+        return super.getNextSequence();
+    }
+
+}