Question

我正在创建一个应用程序，每隔一段时间从网站读取数据并将值发布到屏幕上。我在开始和停止它时遇到了困难。

我可以让循环开始没问题，我也可以阻止它。但如果我再试一次，程序会崩溃。

代码在这里：

    final Timer myTimer = new Timer(); 


    loop.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub

            MyTimerTask mytimertask = new MyTimerTask();
            myTimer.scheduleAtFixedRate(mytimertask, 0, 5000);
        }
    });

    stoploop.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub
            textView.setText("STOPPED");
            myTimer.cancel();

        }
    });


}

private class MyTimerTask extends TimerTask {
    @Override
    public void run() {
        // TODO Auto-generated method stub
        runOnUiThread(new Runnable(){

            public void run() {
                // TODO Auto-generated method stub
                //textView.setText("changed");
                readWebpage(text);
            }

        });

    }

}

我对线程很新，这就是为什么我可能会遗漏一些基本的东西。任何帮助将不胜感激。

谢谢

[编辑]我应该补充一下，我从这里的解决方案中改编了这个： How do I repeat a method every 10 minutes after a button press and end it on another button press

   06-29 01:38:02.958: D/AndroidRuntime(1119): Shutting down VM
   06-29 01:38:02.958: W/dalvikvm(1119): threadid=1: thread exiting with uncaught exception    (group=0x40a13300)
   06-29 01:38:02.968: E/AndroidRuntime(1119): FATAL EXCEPTION: main
   06-29 01:38:02.968: E/AndroidRuntime(1119): java.lang.IllegalStateException: Timer was canceled
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at    java.util.Timer.scheduleImpl(Timer.java:561)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at    java.util.Timer.scheduleAtFixedRate(Timer.java:528)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at com.example.beam.MainActivity$1.onClick(MainActivity.java:67)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at android.view.View.performClick(View.java:4084)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at android.view.View$PerformClick.run(View.java:16966)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at android.os.Handler.handleCallback(Handler.java:615)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at android.os.Handler.dispatchMessage(Handler.java:92)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at android.os.Looper.loop(Looper.java:137)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at android.app.ActivityThread.main(ActivityThread.java:4745)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at java.lang.reflect.Method.invokeNative(Native Method)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at java.lang.reflect.Method.invoke(Method.java:511)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
   06-29 01:38:02.968: E/AndroidRuntime(1119):  at dalvik.system.NativeStart.main(Native Method)
   06-29 01:38:03.028: W/ActivityManager(156):   Force finishing activity com.example.beam/.MainActivity
   06-29 01:38:03.039: W/WindowManager(156): Failure taking screenshot for (246x410) to layer 21010
   06-29 01:38:03.552: W/ActivityManager(156): Activity pause timeout for ActivityRecord{41366318 com.example.beam/.MainActivity}

Answer 1

仅供参考 - 您可能需要考虑使用AlarmManager。它允许您控制间隔，即使您的应用程序未处于活动状态。（我假设你正在创建小部件）。它允许您控制WAKE选项，即您的应用程序不会耗尽电池的方式。

http://developer.android.com/reference/android/app/AlarmManager.html

Answer 2

private class MyTimerTask extends TimerTask {
    @Override
    public void run() {

                mDialogHandler.sendEmptyMessage(DIALOG_OK);

    }

}

 private Handler mDialogHandler = new Handler(){
            public void handleMessage(android.os.Message msg) {
                    switch (msg.what) {
                    case DIALOG_OK:
                            // We are now back in the UI thread
                            //textView.setText("changed");
                            readWebpage(text);
                    }

            };
    };

你试图从一个非法的线程中启动一个线程。我还为你的UI线程困境添加了一些代码。

使用线程每隔一段时间使用一个方法

2 个答案: