比较时间大小

遇到一个比较时间的问题忘记了，有点尴尬，记录一下

public class 比较时间 {

    public static void main(String[] args) throws ParseException {
    	
    	//设置时间的格式
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String t1 = "2017-12-12 12:12:36";
        String t2 = "2017-12-12 12:02:36";
        
        //按照时间格式将字符串转化成Date类型
        Date time1= sdf.parse(t1);
        Date time2= sdf.parse(t2);
        
        //通过compareTo去比较两个时间的大小
        int i = time1.compareTo(time2);
        
        System.out.println(time1);
        System.out.println(time2);
        //输出结果
        //time1>time2,i=1;time1=time2,i=0;time1<time2,i=-1;
        System.out.println(i);
    }
}

其实，比较时间可以考虑比较时间戳

   public static void main(String[] args) throws ParseException {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String t1 = "2017-12-12 12:12:36";
        String t2 = "2017-12-12 12:02:36";
        Date time1 = sdf.parse(t1);
        Date time2 = sdf.parse(t2);

        //time1的时间戳
        long time1Time = time1.getTime();

        //time2的时间戳
        long time2Time = time2.getTime();

        if (time1Time > time2Time)
            System.out.println("t1 > t2");

        if (time1Time == time2Time)
            System.out.println("t1 == t2");

        if (time1Time < time2Time)
            System.out.println("t1 < t2");

    }

其实，compareTo的底层实现就是通过比较时间戳的方式来比较时间的