import java.time.*;
import java.util.concurrent.locks.*;
 
class Test
{
	static Lock lock = new ReentrantLock();
 
	public static void main (String[] args) throws java.lang.Exception
	{
		Thread worker = new Thread(() -> {
			    try {
			        for (int i = 0; i < 20; i++) {
                        Thread.sleep(20);
                        lock.lock();
                        lock.unlock();
			            System.out.println(LocalTime.now());
                    }
			    }
                catch (InterruptedException ex) { }
			});
		worker.start();
		Thread.sleep(100);
		System.out.println("Locking...");
		lock.lock();
		Thread.sleep(500);
		lock.unlock();
		System.out.println("Unlocked");
		worker.join();
	}
}

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