正计时

package work10clock;

import java.util.concurrent.TimeUnit;

public class Click {
	
	private Display hour = new Display(24);
	private Display minute = new Display(60);
	private Display second = new Display(60);

	public void start(){
		while(true){
			second.increase();
			if(second.getValue() == 0){
				minute.increase();
				if(minute.getValue() == 0){
					hour.increase();
				}
			}
			try {
				TimeUnit.SECONDS.sleep(1);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			System.out.printf("%2d:%2d:%2d \n", hour.getValue(), minute.getValue(), second.getValue());
		}
	}
	
	public static void main(String[] args){
		Click click = new Click();
		click.start();
	}
	
}

package work10clock;

public class Display {
	private int value;
	private int limit;
	
	public Display(int limit){
		this.limit = limit;
	}
	
	public void increase(){
		value++;
		if(value == limit){
			value = 0;
		}
	}
	
	public int getValue(){
		return value;
	}
	
}