import java.util.concurrent.locks.*; public class ReentrantLockExample { public static void main(String[] args) { ReentrantLock lock = new ReentrantLock(); new Thread(new NewThread("A", lock)).start(); new Thread(new NewThread("B", lock)).start(); } } public class Shared { public static int count; } public class NewThread implements Runnable { private String name; private ReentrantLock lock; public NewThread(String name, ReentrantLock lock) { this.name = name; this.lock = lock; } @Override public void run() { System.out.println(name + " waiting for lock."); lock.lock(); System.out.println(name + " acquired the lock."); Shared.count++; System.out.println(name + ": " + Shared.count); System.out.println(name + " is sleeping next..."); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(name + " is releasing the lock."); lock.unlock(); } }