java - 移除 ViewGroup 中的 View

Question

我在使用 ViewGroup 和自动生成的 ViewPager 时遇到了一些问题。我想添加一个 View 并删除一个 View ，但每次尝试时我都会收到错误消息:

    01-20 14:05:40.028: E/AndroidRuntime(3615): FATAL EXCEPTION: AsyncTask #1
    01-20 14:05:40.028: E/AndroidRuntime(3615): java.lang.RuntimeException: An error occured while executing doInBackground()
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.os.AsyncTask$3.done(AsyncTask.java:299)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at java.util.concurrent.FutureTask.run(FutureTask.java:239)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at java.lang.Thread.run(Thread.java:856)
    01-20 14:05:40.028: E/AndroidRuntime(3615): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4746)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:823)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.view.View.requestLayout(View.java:15468)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.view.View.requestLayout(View.java:15468)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.view.View.requestLayout(View.java:15468)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.view.View.requestLayout(View.java:15468)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.view.ViewGroup.removeView(ViewGroup.java:3524)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at de.tecfriends.vbtsplash2013.MainActivity$DummySectionFragment.Teilnehmer(MainActivity.java:219)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at de.tecfriends.vbtsplash2013.MainActivity$DummySectionFragment$1.onTaskCompleted(MainActivity.java:148)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at de.tecfriends.vbtsplash2013.BackgroundDownload.doInBackground(BackgroundDownload.java:38)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at de.tecfriends.vbtsplash2013.BackgroundDownload.doInBackground(BackgroundDownload.java:1)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     at java.util.concurrent.FutureTask.run(FutureTask.java:234)
    01-20 14:05:40.028: E/AndroidRuntime(3615):     ... 4 more

在 onCreateView 类中，我设置了一个名为 vGroup 的公共(public) ViewGroup。在所有数据处理结束时，我尝试 vGroup.removeView(vGroup.findViewById(1)); 和 vGroup.addView(modeList); 但我得到上面的错误.

我怎样才能到达原始线程，我可以在其中向此ViewGroup 添加和删除 View ？

Answer 1

ViewRootImpl$CalledFromWrongThreadException: 只有创建 View 层次结构的原始线程才能触及它的 View 。 意味着您正在尝试从后台线程(即非 UI 线程)访问 UI 元素。

vGroup.removeView() 只能从 onPreExecute() 或 onPostExecute() 调用，因为这两个函数在 UI 上运行线程。

private class MyAsyncTask extends AsyncTask<String, Void, String> {

      @Override
      protected String doInBackground(String... params) {
            .... // runs on background / non-UI thread
      }      

      @Override
      protected void onPostExecute(String result) {   
            ... // runs on UI thread            
      }

      @Override
      protected void onPreExecute() {
            ... // runs on UI thread      
      }

      @Override
      protected void onProgressUpdate(Void... values) {
      }
}

Documentation of AsyncTask .