Difference calendar.getTimeInMillis () and System.currentTimeMillis () of

   @Test
    public void test01(){
        Calendar calendar=Calendar.getInstance();
       // calendar.set(2019,06,04,16,42,50);
        long date1=calendar.getTimeInMillis();
        long date2=System.currentTimeMillis();
        Date turnDate1=new Date(date1);
        Date turnDate2=new Date(date2);
        SimpleDateFormat fm=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        System.out.println(fm.format(turnDate1));
        System.out.println(fm.format(turnDate2));

    }

 

Two times are the same.

 2. Performance Comparison

   / ** 
     * Get timestamp of thousands of times each loop 
     * / 
    @Test 
    public  void TEST03 () { 
        Calendar Calendar = Calendar.getInstance ();
         Long the startTime = System.currentTimeMillis ();
         for ( Long I = 0; I <100000 ; I ++ ) {
             Long date1 = calendar.getTimeInMillis (); 
        } 
        System.out.println ( "calender time spent:" + (System.currentTimeMillis () - the startTime)); 

        Long startTime2 = System.currentTimeMillis ();
         for ( Long I = 0; I <100000; I ++ ) {
            Long DATE2 = System.currentTimeMillis (); 
        } 
        System.out.println ( "calender time spent:" + (System.currentTimeMillis () - startTime2)); 
    }

This machine tests found is unstable. nativae way to view the source code System.currentTimeMillis used guess this is the time to take faster. Please correct me