"Java对象的交互"

一个时钟程序,minute自加并打印值到59时变成零同时hour加一,hour到23后变成零.

• display .java文件

public class Display {
	private int limit = 0;
	private int value = 0;

	public Display(int limit) {
		this.limit = limit;
	}

	public void increase() {
		value++;
		if (value == limit) {
			value = 0;
		}
	}

	public int getvalue() {
		return value;
	}

	public static void main(String[] args) {
		Display minute = new Display(59);
		for (;;) {
			minute.increase();
			System.out.println(minute.getvalue());
		}
	}

}

• Clock.java文件

public class Clock {

	private Display minute = new Display(59);
	private Display hour = new Display(24);

	void start() {
		while (true) {
			minute.increase();
			if (minute.getvalue() == 0) {
				hour.increase();
			}
			System.out.printf("%02d:%02d\n",hour.getvalue(),minute.getvalue());
		}
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Clock a = new Clock();
		a.start();

	}

}

关键问题在于怎样实现minute对象与hour对象之间的交互

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