Question

我对类java.util.Timer有疑问，特别是它的cancel()方法。

如果我编写这样的代码并将其调用4000次（例如），它就不会停止执行，我应该猜测该事件：

Timer timer = new Timer();
timer.schedule(new TimerTask() {
    private int id = ++TimerTest.counter;
    @Override
    public void run() {
        if(counter % 100 == 0)
            System.out.println("TimerTest #" + id + "\nI'm doing task: " + task);
        if(counter == 4000 && canceled == true){
            System.out.println("Canceling...");
            timer.cancel();
        }
    }
}, 0);

但不是上面的脚本，我可以将其改为：

Timer timer = new Timer();
timer.schedule(new TimerTask() {
    private int id = ++TimerTest.counter;
    @Override
    public void run() {
        if(counter % 100 == 0)
            System.out.println("TimerTest #" + id + "\nI'm doing task: " + task);
        if(counter == 4000 && canceled == true){
            System.out.println("Canceling...");
        }
    }
}, 0);
timer.cancel();

我一直在寻找同样的问题描述，但我没有遇到任何特别的问题：）

Answer 1

问题似乎在于您似乎正在调用Timer 4000次。相反，你应该有1个计时器，并安排一个时间段。拨打

public void schedule(TimerTask task, long delay, long period)

方法而不是

public void schedule(TimerTask task, long delay)

以下是正确使用的示例：

import java.util.Timer;
import java.util.TimerTask;

public class TimerTest {

    private static int counter = 0;

    private void doTimer() throws InterruptedException {
        Timer timer = new Timer();

        timer.schedule(new TimerTask() {

            @Override
            public void run() {
                counter ++;
                System.out.println("TimerTest #" + counter + " I'm doing task");    
            }
        }, 0,1000);

        //Sleep for 10 seconds before cancelling the timer
        Thread.currentThread().sleep(10000);
        System.out.println("Timer cancelled");
        timer.cancel();
    }

    public static void main(String args[]) throws InterruptedException {
        new TimerTest().doTimer();
    }

}

这会在10秒后停止计时器：

TimerTest #1 I'm doing task
TimerTest #2 I'm doing task
TimerTest #3 I'm doing task
TimerTest #4 I'm doing task
TimerTest #5 I'm doing task
TimerTest #6 I'm doing task
TimerTest #7 I'm doing task
TimerTest #8 I'm doing task
TimerTest #9 I'm doing task
TimerTest #10 I'm doing task
Timer cancelled

定时器取消方法

1 个答案: