讓一個任務整點運行

OneHour.java類：

import java.util.Calendar;
import java.util.Date;
import java.util.Timer;

public class OneHour {

	private final static long JOB_INTERNAL = 1000 * 60 * 60;//隔一個小時運行一次，如果是測試，可以改小一點

	public static void main(String[] args) {
		Timer timer = new Timer();

		Calendar currentTime = Calendar.getInstance();
		currentTime.setTime(new Date());

		int currentHour = currentTime.get(Calendar.HOUR);

		currentTime.set(Calendar.HOUR, currentHour + 1);
		currentTime.set(Calendar.MINUTE, 0);
		currentTime.set(Calendar.SECOND, 0);
		currentTime.set(Calendar.MILLISECOND, 0);

		//下面幾行是相隔時間短一點的測試代碼
		/*
		currentTime.set(Calendar.HOUR, currentTime.get(Calendar.HOUR));
		currentTime.set(Calendar.MINUTE, currentTime.get(Calendar.MINUTE));
		currentTime.set(Calendar.SECOND, currentTime.get(Calendar.SECOND));
		currentTime.set(Calendar.MILLISECOND, currentTime.get(Calendar.MILLISECOND));
		*/

		Date NextHour = currentTime.getTime();
		System.out.println(NextHour);

		timer.scheduleAtFixedRate(new MyTask(), NextHour, JOB_INTERNAL);
	}
}

MyTask.java類：

import java.util.Date;
import java.util.TimerTask;

class MyTask extends TimerTask {

	@Override
	public void run() {
		System.out.println("mytask： " + new Date());
		
		try {
			Thread.sleep(10000);	//設置讓它休眠一段時間，測試下一次運行時間是否還是整點
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

}