java中时间日期的格式化输出

import java.text.SimpleDateFormat;
import java.util.*;
public class CalendarDemo {
 
public String getDateTime(){
 SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd  HH:mm:ss");
 Calendar starttime=Calendar.getInstance();
 String time=dateFormat.format(starttime.getTime());
 return time;
}

public String getDateString(){
 SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
 Calendar starttime=Calendar.getInstance();
 String date=dateFormat.format(starttime.getTime());
 return date ;
 
 
}
public String getDate(){
 SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");
 Calendar starttime=Calendar.getInstance();
 String time=dateFormat.format(starttime.getTime());
 return time;
}


public static void main(String [] agrs){
 CalendarDemo  s= new CalendarDemo();
 
 System.out.println(s.getDate());
 System.out.println(s.getDateString());
 System.out.println(s.getDateTime());
}