Java计算时间差

javaz中对日期时间的处理比较多，代码中列出了3中日期时间计算差值的方法。

比如：现在是2004-03-26 13：31：40
过去是：2004-01-02 11：30：24
我现在要获得两个日期差，差的形式为：XX天XX小时XX分XX秒

方法一：

DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");try{    Date d1 = df.parse("2004-03-26 13:31:40");    Date d2 = df.parse("2004-01-02 11:30:24");    long diff = d1.getTime() - d2.getTime();    long days = diff / (1000 * 60 * 60 * 24);}catch (Exception e){}

方法二：

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");java.util.Date now = df.parse("2004-03-26 13:31:40");java.util.Date date=df.parse("2004-01-02 11:30:24");long l=now.getTime()-date.getTime();long day=l/(24*60*60*1000);long hour=(l/(60*60*1000)-day*24);long min=((l/(60*1000))-day*24*60-hour*60);long s=(l/1000-day*24*60*60-hour*60*60-min*60);System.out.println(""+day+"天"+hour+"小时"+min+"分"+s+"秒");

方法三：

SimpleDateFormat dfs = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");java.util.Date begin=dfs.parse("2004-01-02 11:30:24");java.util.Date end = dfs.parse("2004-03-26 13:31:40");long between=(end.getTime()-begin.getTime())/1000;//除以1000是为了转换成秒long day1=between/(24*3600);long hour1=between%(24*3600)/3600;long minute1=between%3600/60;long second1=between%60/60;System.out.println(""+day1+"天"+hour1+"小时"+minute1+"分"+second1+"秒");

计算时间差及比较时间大小：

String s1="2008-01-25 09:12:09";String s2="2008-01-29 09:12:11";java.text.DateFormat df=new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss");java.util.Calendar c1=java.util.Calendar.getInstance();java.util.Calendar c2=java.util.Calendar.getInstance();try{    c1.setTime(df.parse(s1));    c2.setTime(df.parse(s2));}catch(java.text.ParseException e){    System.err.println("格式不正确");}int result=c1.compareTo(c2);if(result==0)    System.out.println("c1相等c2");else if(result<0)    System.out.println("c1小于c2");else    System.out.println("c1大于c2");