java中时间比较

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"); 

  
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java 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"); 

//时间格式转换
FastDateFormat df = FastDateFormat.getInstance("yyyy-MM-dd HH:mm:ss");  
String date = df.format(java.util.Date());