7-时间加法

 MyTime类：

package 时间加法;

public class MyTime {

    private int h;
    private int m;
    private int s;

    public MyTime(int h, int m, int s) {
        this.h = h;
    }

    public void addHour(int hour) {
        h = ( h + hour ) % 24;
    }

    public void addMinute(int minute) {
        int h = (m + minute) / 60; // 求需要加几小时
        addHour(h);
        m = (m + minute) % 60; // 求小于60的分钟数
    }

    public void addSecond(int second) {
        int minute = (s + second) / 60;
        addMinute(minute);
        s = (s + second) % 60;
    }

    @Override
    public String toString() {
        return h + ": " + m + ": " + s;
    }
}

Test类：

public class Test {
    public static void main(String[] args) {
        MyTime myTime = new MyTime(12, 20, 40);

        myTime.addSecond(30);
        System.out.println(myTime);

        myTime.addMinute(70);
        System.out.println(myTime);

        myTime.addHour(25);
        System.out.println(myTime);
    }
}