Android Gingerbread：无法在未调用Looper.prepare（）的线程内创建处理程序

Question

I have a code like this:

final Context context = this;
Timer timer = new Timer();
timer.schedule(new TimerTask()
{
    @Override
    public void run()
    {
        new CheckMessageTask(context).execute(); //ERROR
    }
}, 2500, 10 * 60 * 1000); //Every 10 Minutes

The Timer should execute CheckMessageTask every 10 minutes. The problem is that this error appears:

E/AndroidRuntime: FATAL EXCEPTION: Timer-0
    java.lang.ExceptionInInitializerError
    at -package-CheckMessageService$1.run(CheckMessageService.java:138)
    at java.util.Timer$TimerImpl.run(Timer.java:284)
    Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
    at android.os.Handler.<init>(Handler.java:121)
    at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
    at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
    at android.os.AsyncTask.<clinit>(AsyncTask.java:152)
    ... 2 more

CheckMessageTask extends Asynctask and doesn't run UI code, so that is not the reason. The code works fine on Android Jelly Bean 4.1.2, but not on Android Gingerbread. How can I fix it?

Answer 1

您不能从UI线程执行Asynctask，这是使用Timer时的情况

Answer 2

Your timer task runs on a different thread. You should load asynctask on the main ui thread

Check the link below under the topic Threading Rules

http://developer.android.com/reference/android/os/AsyncTask.html

The AsyncTask class must be loaded on the UI thread . This is done automatically as of JELLY_BEAN .

So in Jelly bean it works fine.