循环嵌套

public class Demo34 {
    public static void main(String[] args) {
        // 外层控制小时
        for (int hour = 0; hour < 24; hour++) {
            // 内层控制小时之内的分钟
            for (int minute = 0; minute < 60; minute++) {
                //内层控制分钟内的秒
                for (int second = 0; second < 60; second++) {
                    System.out.println(hour + "点" + minute + "分" + second + "秒");
                }
            }
        }
    }
}