java enum 笔记 日期时间格式化

java 的enum也是个类。

public enum Action {
    TURN_LEFT,
    TURN_RIGHT,
    SHOOT;
    public String GetDescription(){
        
        switch(this.ordinal()){
            case 0: return "left";
            case 1: return "right";
            case 2: return "shoot";        
            default:return null;
        }        
    }    
}

e.g.2:

public enum ActionAbstract {
    TURN_LEFT
    {        
        public String GetDesc(){return "left";}
    },
    TURN_RIGHT{        
        public String GetDesc(){return "right";}
    },
    SHOOT{        
        public String GetDesc(){return "shoot";}
    };  //以;结束
    
    public abstract String GetDesc();
}

ps:

  for(Action act : Action.values()){
   System.out.printf( "%s %s %n", act.ordinal() , act );
  }

//日期时间格式化表达式：

  System.out.println(
    String.format(  "%1$tY-%1$tm-%1$td %1$tH:%1$tM:%1$tS",new Date() )
    );
  System.out.printf("%1$tY-%1$tm-%1$td %1$tH:%1$tM:%1$tS",new Date() );