这是我的MainActivity类，其中在单击Button时调用getUserYouTubeFeed方法。
public class MainActivity extends Activity {
// A reference to our list that will hold the video details
private VideosListView listView;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (VideosListView) findViewById(R.id.videosListView);
}
// This is the XML onClick listener to retreive a users video feed
public void getUserYouTubeFeed(View v){
// We start a new task that does its work on its own thread
// We pass in a handler that will be called when the task has finished
// We also pass in the name of the user we are searching YouTube for
new GetYouTubeUserVideosTask(responseHandler, "done").run();
}
// This is the handler that receives the response when the YouTube task has finished
Handler responseHandler = new Handler() {
public void handleMessage(Message msg) {
populateListWithVideos(msg);
};
};
/**
* This method retrieves the Library of videos from the task and passes them to our ListView
* @param msg
*/
private void populateListWithVideos(Message msg) {
// Retreive the videos are task found from the data bundle sent back
Library lib = (Library) msg.getData().get(GetYouTubeUserVideosTask.LIBRARY);
// Because we have created a custom ListView we don't have to worry about setting the adapter in the activity
// we can just call our custom method with the list of items we want to display
listView.setVideos(lib.getVideos());
}
@Override
protected void onStop() {
// Make sure we null our handler when the activity has stopped
// because who cares if we get a callback once the activity has stopped? not me!
responseHandler = null;
super.onStop();
}
}
Logcat错误
08-31 11:34:00.011 27400-27400/com.example.e6530.youtube_playllist E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.e6530.youtube_playllist, PID: 27400
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:4033)
at android.view.View.performClick(View.java:4793)
at android.view.View$PerformClick.run(View.java:19971)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5669)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View$1.onClick(View.java:4028)
at android.view.View.performClick(View.java:4793)
at android.view.View$PerformClick.run(View.java:19971)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5669)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1168)
at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
at java.net.InetAddress.getAllByName(InetAddress.java:215)
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:142)
at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:169)
at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:124)at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:365)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:604)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:519)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:497)
at com.example.e6530.youtube_playllist.GetYouTubeUserVideosTask.run(GetYouTubeUserVideosTask.java:54)
at com.example.e6530.youtube_playllist.MainActivity.getUserYouTubeFeed(MainActivity.java:37)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View$1.onClick(View.java:4028)
at android.view.View.performClick(View.java:4793)
at android.view.View$PerformClick.run(View.java:19971)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5669)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
在上面的代码中，我试图从Youtube获取播放列表视频，然后显示缩略图和＆amp;使用android listview列表中的url。现在，我点击按钮即可获得IllegalStateException。
答案 0 :(得分：1)
而不是尝试使用处理程序对象：
new GetYouTubeUserVideosTask(responseHandler, "done").run();
尝试使用异步任务对象：
new GetYouTubeUserVideosTask(responseHandler, "done").execute();
注意：由于网络操作将尝试在主线程上运行，并且UI已使用此主线程。因此，请避免使用异步任务/意图服务在Mainthread中运行。
有关Handler and Async Task Link 1
的更多信息 的更多信息 的更多信息答案 1 :(得分：0)
在AsyncTask
异常是由于在主ui线程上调用网络线程
执行类似
AsyncTask.execute(new Runnable() {
@Override
public void run() {
// your function calling network thread
}
});