我正在尝试定期执行任务。例如:
class MyTimerTask implements TimerTask
{
public void run() {
// Some actions to perform
}
Timer cleaner = new Timer(true);
cleaner.scheduleAtFixedRate(new MyTimerTask(), 0, PURGE_INTERVAL);
}
但是,run方法只执行一次。但是如果我将第一次延迟设置为10秒,那么run
方法甚至不会执行一次。
示例:
cleaner.scheduleAtFixedRate(new MyTimerTask(), 10, PURGE_INTERVAL);
答案 0 :(得分:0)
我很难弄清楚你的问题究竟是什么,所以这可能不是你要求的,但这个解决方案可能适合你:
public class MyTimerTask implements Runnable {
private static final TimeUnit timeUnit = TimeUnit.SECONDS;
private final ScheduledExecutorService scheduler;
private final int period = 10;
public static void main(String[] args) {
new MyTimerTask();
}
public MyTimerTask() {
scheduler = Executors.newScheduledThreadPool(1);
scheduler.scheduleAtFixedRate(this, period, period, timeUnit);
}
@Override
public void run() {
// This will run every 10 seconds
System.out.println("Ran...");
}
}
答案 1 :(得分:0)
这对我来说听起来像时间单位的问题。确保您正确转换为毫秒。
最简单的方法是使用Java TimeUnit
。
Timer cleaner = new Timer(true);
cleaner.scheduleAtFixedRate(new MyTimerTask(),
TimeUnit.SECONDS.toMillis(10),
TimeUnit.SECONDS.toMillis(30));
也可能是由于在守护进程模式下启动Timer
引起的。如果所有main方法都设置了定时器然后返回定时器将永远不会执行,因为它是最后剩下的线程,并且因为它是守护程序线程,JVM将退出。
要解决这个问题,要么使计时器线程不是守护进程(即在构造函数中传递false
),要么让主线程在退出之前等待用户输入。
以下是使用上述两个示例的示例:
public class TimerDemo extends TimerTask {
public void run() {
System.out.printf("Time is now %s%n", LocalTime.now());
}
public static void main(String[] args) throws IOException {
Timer timer = new Timer(true);
timer.scheduleAtFixedRate(new TimerDemo(),
TimeUnit.SECONDS.toMillis(5),
TimeUnit.SECONDS.toMillis(10));
System.out.printf("Program started at %s%n", LocalTime.now());
System.out.println("Press enter to exit");
try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
// Wait for user to press enter
reader.readLine();
}
System.out.println("Bye!");
}
}
运行它的输出:
Program started at 14:49:42.207
Press enter to exit
Time is now 14:49:46.800
Time is now 14:49:56.799
Time is now 14:50:06.799
Time is now 14:50:16.799
Time is now 14:50:26.799
[I pressed 'enter']
Bye!
Process finished with exit code 0