假設我有這個代碼： public static void main(String[] args)  {        Scanner key01 = new Scanner(System.in);    int input;    System.out.println("Please enter a int.");      while (key01.hasNext())       {       if(key01.hasNextInt())        {         input = key01.nextInt();         System.out.println("Thanks for input!");        }       else       {        System.out.println("You must enter an Int");        key01.next(); //Why does this statement prevent an infinite loop?          //That statement prevents         //the program from constantly printing "you must enter an int"       }    }}key01.next（） 如何防止控制臺不斷打印出錯誤消息？