Java：定時器在命令時間之前執行

Question

我想在特定時間執行 foo() 。 這是我的代碼：

public void scheduler() throws ParseException {
    java.util.Timer _timer = new Timer();
    TimerTask tt;
    tt = new TimerTask() {
        @Override
        public void run() {
            foo();
        }
    };
    DateFormat dateFormatter = new SimpleDateFormat("HH:mm:ss");
    java.util.Date date = dateFormatter.parse("14:26:00");
    _timer.schedule(tt,date);
}

public void foo(){
    System.out.println("Done");
}

但是 foo() 實際上是在我運行代碼本身時執行的，而不是在指定的時間。 請幫忙

Answer 1

public void scheduler() throws ParseException {
    java.util.Timer _timer = new Timer();
    TimerTask tt;
    tt = new TimerTask() {
        @Override
        public void run() {
            foo();
        }
    };

  //Get the Date corresponding to 14:26:00 pm today.
    Calendar calendar = Calendar.getInstance();
    calendar.set(Calendar.HOUR_OF_DAY, 14);
    calendar.set(Calendar.MINUTE, 26);
    calendar.set(Calendar.SECOND, 0);
    Date time = calendar.getTime();
    _timer.schedule(tt,time);
}

public void foo(){
    System.out.println("Done");
}

**Note:** _timer.schedule(tt, time):- Schedules the specified task for execution at the specified time. If the time is in the past, the task is scheduled for immediate execution.