获取某时刻时间转换测试

目的：取当天零点时间

 

@Test
	public void justTest1(){
		for(int i=0;i<Integer.MAX_VALUE/1000;i++){
		GregorianCalendar c_start=new GregorianCalendar();
		c_start.setTime(new Date());
		c_start.set(Calendar.HOUR_OF_DAY, 0);
		c_start.set(Calendar.MINUTE, 0);
		c_start.set(Calendar.SECOND, 0);
		c_start.set(Calendar.MILLISECOND, 0);
		}
	}
	
	@Test
	public void justTest2() throws ParseException{
		for(int i=0;i<Integer.MAX_VALUE/1000;i++){
			SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
			sdf.parse(sdf.format(new Date()));
		}
	}

 结果：