JAVA获取时间戳，哪个更快详解编程语言

//方法 一   
System.currentTimeMillis();    
//方法 二   
Calendar.getInstance().getTimeInMillis();   
//方法 三   
new Date().getTime(); 

    import java.util.Calendar;   
    import java.util.Date;   
       
    public class TimeTest {   
        private static long _TEN_THOUSAND=10000;   
        public static void main(String[] args) {   
            long times=1000*_TEN_THOUSAND;   
            long t1=System.currentTimeMillis();   
            testSystem(times);   
            long t2=System.currentTimeMillis();   
            System.out.println(t2-t1);   
            testCalander(times);   
            long t3=System.currentTimeMillis();   
            System.out.println(t3-t2);   
            testDate(times);   
            long t4=System.currentTimeMillis();   
            System.out.println(t4-t3);   
        }   
           
        public static void testSystem(long times){//use 188   
            for(int i=0;i<times;i++){   
                long currentTime=System.currentTimeMillis();   
            }   
        }   
       
        public static void testCalander(long times){//use 6299   
            for(int i=0;i<times;i++){   
                long currentTime=Calendar.getInstance().getTimeInMillis();   
            }   
        }   
           
        public static void testDate(long times){   
            for(int i=0;i<times;i++){   
                long currentTime=new Date().getTime();   
            }   
               
        }   
       
    }  

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