antarmuka runnable di java

public class CountDown {
	// A Java code that creates 5 parallel tasks
	// performing countdown from 5 to 0
	public static void main(String[] args) {
		CountDown application = new CountDown();
		application.start();	
	}
	// Method for spawning 5 parallel threads of execution
	public void start() {
		for(int i=1; i<=5; i++)
			new Thread(new CountDownHandler(5, i)).start();
	}
	// Utility class for handling count down per thread
	// that implements the Runnable interface
	private class CountDownHandler implements Runnable {
		private int id;
		private int counter;
		public CountDownHandler(int counter, int id) {
			this.counter = counter;
			this.id = id;
		}
		public String status() {
			return "id#" + id + " " +
			((counter >= 0) ? counter : "LiftOff!");
		}
		public void run() {
			while(counter >= -1) {
				System.out.println(status());
				counter--;
				try {
					Thread.sleep(1000);
				} catch(Exception e) {

				}
			}
		}
	}
}
Wissam