运行时间

public class Time{
 private long start,end;
 public void testFor(){
 start = System.nanoTime();
 for(int i = 1,sum = 0;i<=100;i++)
 sum += i;
 end = System.nanoTime();
 }
 public long getUsedTime(){
 testFor();
 return end-start;
 }
 public static void main(String args[]){
 NanoTime testFor = new NanoTime();
 System.out.println(testFor.getUsedTime());
 }
 }