计算时间差

SimpleDateFormat simpleFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm");//如2016-08-10 20:40  

计算天数差。

String fromDate = simpleFormat.format("2016-05-01 12:00");  
String toDate = simpleFormat.format("2016-06-01 12:00");  
long from = simpleFormat.parse(fromDate).getTime();  
long to = simpleFormat.parse(toDate).getTime();  
int days = (int) ((to - from)/(1000 * 60 * 60 * 24));

 2.计算小时差

String fromDate = simpleFormat.format("2016-05-01 12:00");  
String toDate = simpleFormat.format("2016-05-01 14:00");  
long from = simpleFormat.parse(fromDate).getTime();  
long to = simpleFormat.parse(toDate).getTime();  
int hours = (int) ((to - from)/(1000 * 60 * 60)); 

3.计算分钟差

String fromDate = simpleFormat.format("2016-05-01 12:00");  
String toDate = simpleFormat.format("2016-05-01 12:50");  
long from = simpleFormat.parse(fromDate).getTime();  
long to = simpleFormat.parse(toDate).getTime();  
int minutes = (int) ((to - from)/(1000 * 60));