代码片断：统计程序执行的时间

double beginTime = System.currentTimeMillis();

//do sth.

double endTime = System.currentTimeMillis();

double second = (endTime – beginTime)/1000;

double minute = second/60;

double hour = minute/60;

System.out.println("总耗时："+second+"秒,"+minute+"分，"+hour+"小时");