Java tutorial
import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; public class Test { public static void main(String[] args) { final Lock firstLock = new ReentrantLock(); final Lock secondLock = new ReentrantLock(); firstLock.lock(); Thread secondThread = new Thread(new Runnable() { public void run() { secondLock.lock(); firstLock.lock(); } }); secondThread.start(); try { Thread.sleep(250); } catch (InterruptedException e) { e.printStackTrace(); } secondLock.lock(); secondLock.unlock(); firstLock.unlock(); } }