AsyncTask在doInBackground（）中崩溃

Question

您会看到我正在尝试在此适配器上加载一些数据，但是无法创建AsyncTask来显示进度对话框。

这是程序的完整代码，它给我错误。 我已完全修改，因此请勿编辑任何UI。

public class MatchNowGames extends Activity {
Games games = new Games();
Iterator iterador;
private ProgressDialog dialog;
GamesArrayAdapter adapter;
ListView lv;
public void onCreate(Bundle savedInstanceState) {       
    super.onCreate(savedInstanceState);        
    // INCIO PROGRAMA        
    setContentView(R.layout.games_list);
    lv = (ListView) this.findViewById(R.id.gamesLV);
    // Creamos el thread
    dialog = new ProgressDialog(this);
    dialog.setMessage("Cargando...");
    dialog.setTitle("Progreso");
    dialog.setCancelable(false);

    // INIT VARIABLES
    new CargandoJuegos().execute(); 
    adapter = new GamesArrayAdapter(App.context().getApplicationContext(), R.layout.games_list, games.getGames());      


}
private class CargandoJuegos extends AsyncTask<Void, Void, Void>{
    protected void onPreExecute() {
            dialog.show();
            }

     protected Void doInBackground(Void... urls) {
         // AÑADIMOS LOS JUEGOS
        try {
            games.addGames(MatchNow.serverGames);
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {

                e.printStackTrace();
            }
        } catch (JSONException e) {}
        return null;
     }
     protected void onPostExecute(Void unused) {
         dialog.dismiss();
         lv.setAdapter(adapter);
     }


  }

}

这是显示进度对话框时我们应该做的：

// Start progress dialog
    try {
            games.addGames(MatchNow.serverGames);
        } catch (JSONException e) {
            e.printStackTrace();
        }
    // Finish progress dialog
    GamesArrayAdapter adapter = new GamesArrayAdapter(App.context().getApplicationContext(), R.layout.games_list, games.getGames());
    ListView lv = (ListView) this.findViewById(R.id.gamesLV);
    lv.setAdapter(adapter);

提前非常感谢您=）

日志：

09-07 02:18:07.916: D/AndroidRuntime(890): Shutting down VM
09-07 02:18:07.916: W/dalvikvm(890): threadid=3: thread exiting with uncaught exception (group=0x4001b188)
09-07 02:18:07.926: E/AndroidRuntime(890): Uncaught handler: thread main exiting due to uncaught exception
09-07 02:18:07.936: E/AndroidRuntime(890): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{match.now.play/match.now.play.MatchNowGames}: java.lang.NullPointerException
09-07 02:18:07.936: E/AndroidRuntime(890):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
09-07 02:18:07.936: E/AndroidRuntime(890):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
09-07 02:18:07.936: E/AndroidRuntime(890):  at android.app.ActivityThread.access$2200(ActivityThread.java:119)
09-07 02:18:07.936: E/AndroidRuntime(890):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
09-07 02:18:07.936: E/AndroidRuntime(890):  at android.os.Handler.dispatchMessage(Handler.java:99)
09-07 02:18:07.936: E/AndroidRuntime(890):  at android.os.Looper.loop(Looper.java:123)
09-07 02:18:07.936: E/AndroidRuntime(890):  at android.app.ActivityThread.main(ActivityThread.java:4363)
09-07 02:18:07.936: E/AndroidRuntime(890):  at java.lang.reflect.Method.invokeNative(Native Method)
09-07 02:18:07.936: E/AndroidRuntime(890):  at java.lang.reflect.Method.invoke(Method.java:521)
09-07 02:18:07.936: E/AndroidRuntime(890):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
09-07 02:18:07.936: E/AndroidRuntime(890):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
09-07 02:18:07.936: E/AndroidRuntime(890):  at dalvik.system.NativeStart.main(Native Method)
09-07 02:18:07.936: E/AndroidRuntime(890): Caused by: java.lang.NullPointerException
09-07 02:18:07.936: E/AndroidRuntime(890):  at android.app.Activity.findViewById(Activity.java:1612)
09-07 02:18:07.936: E/AndroidRuntime(890):  at match.now.play.MatchNowGames.<init>(MatchNowGames.java:40)

我解决了1612行的问题，这是一个疏忽。 Logcat确实带来了问题。 抱歉给你带来不便。

    09-07 02:18:07.936: E/AndroidRuntime(890):  at java.lang.Class.newInstanceImpl(Native Method)
    09-07 02:18:07.936: E/AndroidRuntime(890):  at java.lang.Class.newInstance(Class.java:1479)
    09-07 02:18:07.936: E/AndroidRuntime(890):  at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
    09-07 02:18:07.936: E/AndroidRuntime(890):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2409)
    09-07 02:18:07.936: E/AndroidRuntime(890):  ... 11 more


09-07 02:34:31.486: D/dalvikvm(930): GC freed 404 objects / 23688 bytes in 60ms
09-07 02:34:32.976: I/global(930): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
09-07 02:34:32.986: I/System.out(930): {"games":[{"id":"1","image":"http:\/\/cibermaniacos.com\/images\/stories\/call_of_duty_modern_warfare_3_desvelado_dest01.jpg","name":"Call Of Duty MW3","descrip":"","modes":[{"id":"1","name":"1vs1","mode_icon":"none"},{"id":"2","name":"2vs2","mode_icon":"none"}],"console":"PS3,XBOX"},{"id":"2","image":"http:\/\/www.hry-na-mobil.eu\/data\/ikonky\/hry-na-mobil-eu\/46801\/call-of-duty-world-at-war-codww-1000x1000jpg-12.png","name":"Prueba","descrip":"afafs","modes":[{"id":"1","name":"1vs1","mode_icon":"none"},{"id":"2","name":"2vs2","mode_icon":"none"}],"console":"steam,PS3"},{"id":"4","image":"http:\/\/cibermaniacos.com\/images\/stories\/call_of_duty_modern_warfare_3_desvelado_dest01.jpg","name":"Call Of Duty MW2","descrip":"AWDAWD","modes":[{"id":"1","name":"1vs1","mode_icon":"none"},{"id":"2","name":"2vs2","mode_icon":"none"}],"console":"steam,PS3"}]}                  
09-07 02:34:33.036: I/System.out(930): Call Of Duty MW2
09-07 02:34:33.046: I/System.out(930): Call Of Duty MW3
09-07 02:34:33.068: W/dalvikvm(930): threadid=15: thread exiting with uncaught exception (group=0x4001b188)
09-07 02:34:33.068: E/AndroidRuntime(930): Uncaught handler: thread AsyncTask #1 exiting due to uncaught exception
09-07 02:34:33.086: E/AndroidRuntime(930): java.lang.RuntimeException: An error occured while executing doInBackground()
09-07 02:34:33.086: E/AndroidRuntime(930):  at android.os.AsyncTask$3.done(AsyncTask.java:200)
09-07 02:34:33.086: E/AndroidRuntime(930):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
09-07 02:34:33.086: E/AndroidRuntime(930):  at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
09-07 02:34:33.086: E/AndroidRuntime(930):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
09-07 02:34:33.086: E/AndroidRuntime(930):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)
09-07 02:34:33.086: E/AndroidRuntime(930):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
09-07 02:34:33.086: E/AndroidRuntime(930):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
09-07 02:34:33.086: E/AndroidRuntime(930):  at java.lang.Thread.run(Thread.java:1096)
09-07 02:34:33.086: E/AndroidRuntime(930): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
09-07 02:34:33.086: E/AndroidRuntime(930):  at android.os.Handler.<init>(Handler.java:121)
09-07 02:34:33.086: E/AndroidRuntime(930):  at android.app.Activity.<init>(Activity.java:673)
09-07 02:34:33.086: E/AndroidRuntime(930):  at match.now.play.functions.Game.<init>(Game.java:52)
09-07 02:34:33.086: E/AndroidRuntime(930):  at match.now.play.functions.Games.addGames(Games.java:58)
09-07 02:34:33.086: E/AndroidRuntime(930):  at match.now.play.MatchNowGames$CargandoJuegos.doInBackground(MatchNowGames.java:67)
09-07 02:34:33.086: E/AndroidRuntime(930):  at match.now.play.MatchNowGames$CargandoJuegos.doInBackground(MatchNowGames.java:1)
09-07 02:34:33.086: E/AndroidRuntime(930):  at android.os.AsyncTask$2.call(AsyncTask.java:185)
09-07 02:34:33.086: E/AndroidRuntime(930):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
09-07 02:34:33.086: E/AndroidRuntime(930):  ... 4 more

Answer 1

您可以参考以下内容： 无法在ProgressDialog的AsyncTask内未调用Looper.prepare（）的线程内创建处理程序

Answer 2

看来doInBackground()方法中唯一的真实代码是这样的：

  games.addGames(MatchNow.serverGames);

但是，您没有向我们展示addGames()方法中会发生什么。 您是否正在尝试使用该方法对UI进行操作？ 如果是这样，那将是一个问题。

doInBackground()不能直接进行任何UI调用。 如果UI需要后台处理过程中进行更新，你会经常打电话publishProgress()从内部doInBackground()来触发onProgressUpdate() 您可以在onProgressUpdate()进行UI调用。