syncblock.java

Java Thread Programming (Source

public class SyncBlock extends Object {
	private Object longLock;

	public SyncBlock() {
		longLock = new Object();
	}

	public void doStuff() {
		print("about to try to get exclusive access " +
				"to longLock");

		synchronized ( longLock ) {
			print("got exclusive access to longLock");
			try { Thread.sleep(10000); } 
			catch ( InterruptedException x ) { }
			print("about to relinquish exclusive access to " +
					"longLock");
		}
	}

	private static void print(String msg) {
		String name = Thread.currentThread().getName();
		System.err.println(name + ": " + msg);
	}

	private static Thread launch(
				final SyncBlock sb, 
				String name
			) {

		Runnable r = new Runnable() {
				public void run() {
					print("in run()");
					sb.doStuff();
				}
			};
		
		Thread t = new Thread(r, name);
		t.start();

		return t;
	}

	public static void main(String[] args) {
		try {
			SyncBlock sb = new SyncBlock();
	
			Thread t1 = launch(sb, "T1");
			Thread.sleep(500);

			Thread t2 = launch(sb, "T2");
			Thread t3 = launch(sb, "T3");

			Thread.sleep(1000);

			print("about to interrupt T2");
			t2.interrupt();
			print("just interrupted T2");

		} catch ( InterruptedException x ) {
			x.printStackTrace();
		}
	}
}