Multithreading: sync

synchronized void incrementSync() {     count = count + 1;}

ReentrantLock lock = new ReentrantLock();int count = 0;void increment() {     lock.lock();     try {         count++;     } finally {         lock.unlock();     }}

ExecutorService executor = Executors.newFixedThreadPool(2);ReentrantLock lock = new ReentrantLock();  executor.submit(() -> {     lock.lock();     try {         sleep(1);     } finally {         lock.unlock();     }});  executor.submit(() -> {     System.out.println("Locked: " + lock.isLocked());     System.out.println("Held by me: " + lock.isHeldByCurrentThread());     boolean locked = lock.tryLock();     System.out.println("Lock acquired: " + locked);});stop(executor);

ExecutorService executor = Executors.newFixedThreadPool(2);Map<String, String> map = new HashMap<>();ReadWriteLock lock = new ReentrantReadWriteLock();  executor.submit(() -> {     lock.writeLock().lock();     try {         sleep(1);         map.put("foo", "bar");     } finally {         lock.writeLock().unlock();     }});

Runnable readTask = () -> {     lock.readLock().lock();     try {         System.out.println(map.get("foo"));         sleep(1);     } finally {         lock.readLock().unlock();     }};  executor.submit(readTask); executor.submit(readTask);stop(executor);

ExecutorService executor = Executors.newFixedThreadPool(2);StampedLock lock = new StampedLock();  executor.submit(() -> {     long stamp = lock.tryOptimisticRead();     try {         System.out.println("Optimistic Lock Valid: " + lock.validate(stamp));         sleep(1);         System.out.println("Optimistic Lock Valid: " + lock.validate(stamp));         sleep(2);         System.out.println("Optimistic Lock Valid: " + lock.validate(stamp));     } finally {         lock.unlock(stamp);     }});  executor.submit(() -> {     long stamp = lock.writeLock();     try {         System.out.println("Write Lock acquired");         sleep(2);     } finally {         lock.unlock(stamp);         System.out.println("Write done");     }});stop(executor);

ExecutorService executor = Executors.newFixedThreadPool(10);Semaphore semaphore = new Semaphore(5);Runnable longRunningTask = () -> {     boolean permit = false;     try {         permit = semaphore.tryAcquire(1, TimeUnit.SECONDS);         if (permit) {             System.out.println("Semaphore acquired");             sleep(5);         } else {             System.out.println("Could not acquire semaphore");         }     } catch (InterruptedException e) {         throw new IllegalStateException(e);     } finally {         if (permit) {             semaphore.release();         }     }}IntStream.range(0, 10)     .forEach(i -> executor.submit(longRunningTask));stop(executor);