学步园

		Date date =new Date();
		String time="HH:MM:SS";
		SimpleDateFormat formater=new SimpleDateFormat(time);
		String dateStr=formater.format(date);
		System.out.println(dateStr);

		SimpleDateFormat formater2=new SimpleDateFormat("yyyy/MM/dd");
		String dateStr2=formater2.format(new Date());
		System.out.println(dateStr2);

定时调度线程

		Timer timer =new Timer();
		TimerTask task =new TimerTask() {
			@Override
			public void run() {
				// TODO Auto-generated method stub
				System.out.println(new Date());
			}
		};
		timer.schedule(task, 1000,2000);
		
		//内部类的写法
		new Timer().schedule(new TimerTask() {		
			@Override
			public void run() {
				// TODO Auto-generated method stub
				System.out.println(new Date());
			}
		},1000,2000);

public class Test{   
    public static void main(String[] args) {   
        User user1 = new User();   
        user1.setName("a");   
        user1.setOrder(1);   
        User user2 = new User();   
        user2.setName("b");   
        user2.setOrder(2);   
        List<User> list = new ArrayList<User>();   
        list.add(user2);   
        list.add(user1);   
        Collections.sort(list,new Comparator<User>(){   
           public int compare(User arg0, User arg1) {   
               return arg0.getOrder().compareTo(arg1.getOrder());   
            }   
        });   
       for(User u : list){   
           System.out.println(u.getName());   
        }   
     }   
} 

默认为升序，将return arg0.getOrder().compareTo(arg1.getOrder());    改为：

return arg1.getOrder().compareTo(arg0.getOrder());   就成倒序的了