應用程序崩潰，當我按下返回按鈕

我是Android編程的新手。我有一個應用程序與一些活動和SplashActivity，這是首發。類似的問題已經被問到，但沒有一個答案對我有幫助，例如，加入finish()功能在我EinkaufsListe-Activity甚至添加此方法應用程序崩潰，當我按下返回按鈕

@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
    if (keyCode == KeyEvent.KEYCODE_BACK) { 
     Intent intent = new Intent(this, MainActivity.class); 
      startActivity(intent); 
      super.onStop(); 
     return true; 
    } 

    return super.onKeyDown(keyCode, event); 
}

與添加的super.onStop().沒有！我有一個應用程序與幾個Activities和SplashActivity，這是首發。當我在ShopList-Activity並按下「返回」按鈕應用程序崩潰，並說：

 0-07 13:37:56.250: E/AndroidRuntime(1124): java.lang.RuntimeException: Unable to  stop activity {de.abayev.theapp/de.abayev.theapp.EinkaufsListe}:  java.lang.NullPointerException 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3188) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.app.ActivityThread.handleStopActivity(ActivityThread.java:3234) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.app.ActivityThread.access$1100(ActivityThread.java:135) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1223) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.os.Handler.dispatchMessage(Handler.java:102) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.os.Looper.loop(Looper.java:136) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.app.ActivityThread.main(ActivityThread.java:5017) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at java.lang.reflect.Method.invoke(Method.java:515) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at dalvik.system.NativeStart.main(Native Method) 
10-07 13:37:56.250: E/AndroidRuntime(1124): Caused by: java.lang.NullPointerException 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.app.Activity.performStop(Activity.java:5388) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3185) 
10-07 13:37:56.250: E/AndroidRuntime(1124):  ... 11 more

這裏是我的清單：

 <application 
    android:allowBackup="true" 
    android:icon="@drawable/ic_launcher" 
    android:label="@string/app_name" 
    android:theme="@style/AppTheme" > 
    <activity 
     android:name=".MainActivity" 
     android:label="@string/app_name" > 
     <intent-filter> 


      <category android:name="android.intent.category.DEFAULT" /> 
     </intent-filter> 
    </activity> 
    <activity 
     android:label="@string/app_name" 
     android:theme="@android:style/Theme.NoTitleBar.Fullscreen" 
     android:name=".SplashActivity"> 
     <intent-filter > 
      <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
    <activity 
     android:label="@string/app_name" 
     android:theme="@android:style/Theme.NoTitleBar.Fullscreen" 
     android:name=".EinkaufsListe"> 
     <intent-filter > 

      <category android:name="android.intent.category.DEFAULT" /> 
     </intent-filter> 
    </activity> 
    <activity 
     android:name=".MHD_Liste"> 
     <intent-filter > 
      <category android:name="android.intent.category.DEFAULT" /> 
     </intent-filter> 
    </activity> 

    <service android:name=".MyAlarmService" 
      android:enabled="true" /> 

    <receiver android:name=".MyReceiver"/> 

</application>

I`ve真的像搜索天沒有什麼幫助。如果你需要更多的代碼讓我知道。

編輯： 這裏距離EinkaufsListe

protected void onCreate(Bundle savedInstanceState) 
{ 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.einkaufsliste); 

    openDB();   
    eddit1 = (EditText) findViewById (R.id.edittxt1); 
    eddit1.setOnKeyListener(OnKey); 

    LV = (ListView) findViewById (R.id.liVi1); 
    registerForContextMenu(LV); 

    startManagingCursor(cursor_main); 
    update_list(); 

    LV.setAdapter(cur_adapter); 

    Intent myIntent = new Intent(EinkaufsListe.this, MyReceiver.class); 
     pendingIntent = PendingIntent.getBroadcast(EinkaufsListe.this, 0, myIntent,0); 

} // OnCreate

編輯2我的OnCreate：

好吧，我不知道該代碼可以是更相關的，所以我只是張貼了整個休息的類：

// Methode für das Eingabefeld mit übergabe an DB 
    public OnKeyListener OnKey = new OnKeyListener()  
    { 

     @Override 
     public boolean onKey(View v, int keyCode, KeyEvent event) 
     { 
      if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER)) 
      { 
String writtenText = eddit1.getText().toString(); 

       if(writtenText.indexOf(",") != -1) 
       { 
        String a; 
        String b; 

        a = writtenText.substring(0, writtenText.indexOf(",")); 
        b = writtenText.substring(writtenText.indexOf(",")+1, writtenText.length()); // writtenText.indexOf(",")+1 um Abschnitt nach dem Komma zu beginnen     

        myDb.insertRow(a,b,null,EinkaufTabelle); //neue Zeile in DB anfügen 
        eddit1.setText(""); 
        update_list(); 
       } 
       else 
       { 
        myDb.insertRow(writtenText," ohne Produktart ",null,EinkaufTabelle); //neue Zeile in DB anfügen 
        eddit1.setText(""); 
        update_list(); 
       } 
      } 
      return false; 
     } // OnKey 

    }; // OnKeyListener 
////////////////////////////////////////////__Datenbank-Methoden__///////////////////////////////////////// 
    @Override 
    protected void onDestroy() { 
     super.onDestroy(); 
     if(null != myDb) 
     closeDB(); 
    } 

    private void openDB() { 
     myDb = new DBAdapter(this); 
     myDb.open(); 
    } 

    private void closeDB() { 
     myDb.close(); 
    } 

    public DBAdapter getDB() 
    { 
     DBAdapter angefragte_DB = myDb; 
     return angefragte_DB; 
    } 

/////////////////////////////////////////////__ListView Methoden__///////////////////////////////////////// 
public void onToggleClicked(View view) 
{ 
    boolean on = ((ToggleButton) view).isChecked(); 
    if (on) 
    { checked = true; update_list(); } 
    else 
    { checked = false; update_list(); } 
} // onToggleClicked, nach dem Beispiel von developer.Android.com 

protected void update_list() 
{ 
    if (checked == true) 
     cursor_main = myDb.orderRows(EinkaufTabelle); 
    else 
     cursor_main = myDb.getAllRows(EinkaufTabelle); 
    //startManagingCursor(cursor); 

    final String[] anzeigeSpalten = new String[]{ "name", "productType"}; 
    final int[] anzeigeViews  = new int[] { R.id.dataLV_tv, R.id.dataLV_tv2 }; 
     cur_adapter    = new SimpleCursorAdapter(this, R.layout.datensaetze_listview, cursor_main, anzeigeSpalten, anzeigeViews); 

     LV.setAdapter(cur_adapter); 
} // update_list 

//Contextmenu anlegen 
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) 
{ 
    MenuInflater inflater = getMenuInflater(); 

    inflater.inflate(R.menu.context_menu, menu); 

}; // OnCreateContextMenu 

// 
public boolean onContextItemSelected(MenuItem item) 
{ 
    AdapterContextMenuInfo menuInfo = (AdapterContextMenuInfo) item.getMenuInfo(); 
    int rowId; 

    cursor_main = cur_adapter.getCursor(); 
    cursor_main.moveToPosition(menuInfo.position); 
    rowId = cursor_main.getInt(cursor_main.getColumnIndex("_id")); 
    itemId = cursor_main.getInt(cursor_main.getColumnIndex("_id")); 

    switch (item.getItemId()) 
    { 
      case R.id.loeschen : myDb.deleteRow(rowId, EinkaufTabelle); break; 

      case R.id.mhd  : showDialog(MHD_DIALOG); 
            break; 

      default: break;  
    } 
    update_list(); 
    return true; 
} // onContextItemSelected 

/////////////////////////////////////////////__Dialog Methoden__///////////////////////////////////////// 
protected Dialog onCreateDialog(int num) 
{  Dialog rückgabe = null; 

     switch(num) 
     { 
      case MHD_DIALOG: rückgabe = zeigeMHDDialog(); 
          break; 

      default  : break; 
     } 

    return rückgabe; 
} // onCreateDialog 

private DatePickerDialog zeigeMHDDialog() 
{ 

    final DatePickerDialog.OnDateSetListener datelistener; 
    datelistener = new DatePickerDialog.OnDateSetListener() { 
         public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) // wird wegen des CallBack Meachanismus erst beim Schließen, 
         {                     // des DatePickerDialogs aufgerufen 
          int Tag = dayOfMonth; 
          int Monat = monthOfYear; 
          int Jahr = year; 
          String ablaufsDat; 

          //switch-Anweisung falls Tag < 7 muss Benutzter trotzdem richtig gewarnt werden 
          switch(dayOfMonth) 
          { 
          case 7: Tag = 30; Monat = monthOfYear - 1; break; 
          case 6: Tag = 29; Monat = monthOfYear - 1; break; 
          case 5: Tag = 28; Monat = monthOfYear - 1; break; 
          case 4: Tag = 27; Monat = monthOfYear - 1; break; 
          case 3: Tag = 26; Monat = monthOfYear - 1; break; 
          case 2: Tag = 25; Monat = monthOfYear - 1; break; 
          case 1: Tag = 24; Monat = monthOfYear - 1; break; 
          default: Tag = dayOfMonth - 7; Monat = monthOfYear; Jahr = year; break; 
          } 

          if(monthOfYear == 0)  // per Definition gehen die Monate im PC von 0 - 11 
          { 
           switch(dayOfMonth) 
           { 
           case 7: Tag = 30; Monat = 11; Jahr = year - 1; break; 
           case 6: Tag = 29; Monat = 11; Jahr = year - 1; break; 
           case 5: Tag = 28; Monat = 11; Jahr = year - 1; break; 
           case 4: Tag = 27; Monat = 11; Jahr = year - 1; break; 
           case 3: Tag = 26; Monat = 11; Jahr = year - 1; break; 
           case 2: Tag = 25; Monat = 11; Jahr = year - 1; break; 
           case 1: Tag = 24; Monat = 11; Jahr = year - 1; break; 
           default: Tag = dayOfMonth - 7; Monat = monthOfYear; Jahr = year; break; 
           } 
          } 


          String name = cursor_main.getString(cursor_main.getColumnIndex("name")); 
          String productType = cursor_main.getString(cursor_main.getColumnIndex("productType")); 

          neuesDat = Tag + "." + (Monat +1) + "." + Jahr ; 
          ablaufsDat = dayOfMonth + "." + (monthOfYear +1) + "." + year ; 

          myDb.updateRowDate(itemId, ablaufsDat); 
          myDb.insertRow(name, productType, ablaufsDat, MHD_Tabelle); // in die MHD Tabelle einfügen 

          Toast.makeText(getApplicationContext(), "Mindesthaltbarkeitsdatum wurde eingestellt. Sie können es in der Liste für die aufzubewahrenden Produkte einsehen", Toast.LENGTH_LONG).show(); 

          Calendar calendar = Calendar.getInstance(); 
          calendar.set(Calendar.YEAR, Jahr); 
          calendar.set(Calendar.MONTH, Monat); 
          calendar.set(Calendar.DAY_OF_MONTH, Tag); 

          AlarmManager alarmManager = (AlarmManager)getSystemService(ALARM_SERVICE); 
          alarmManager.set(AlarmManager.RTC, calendar.getTimeInMillis(), pendingIntent); 
         } //onDateSet 
         }; //datelistener 

    // Dialog erzeugen und Datum auf heute setzen 
    Calendar c = Calendar.getInstance(); 
    int J = c.get(Calendar.YEAR); 
    int M = c.get(Calendar.MONTH); 
    int T = c.get(Calendar.DAY_OF_MONTH); 

    DatePickerDialog dialog = new DatePickerDialog (this, datelistener, J, M, T); 
    return dialog; 
} 

// methode für den back Button 
@Override 
public void onBackPressed() { 

    Intent intent_x = new Intent(this, MainActivity.class); 
    startActivity(intent_x); 
    finish(); 
} 


} // end of class

這裏是跟蹤清洗：

10-07 15:00:24.100: E/AndroidRuntime(1435): FATAL EXCEPTION: main 
10-07 15:00:24.100: E/AndroidRuntime(1435): Process: de.abayev.theshapp, PID: 1435 
10-07 15:00:24.100: E/AndroidRuntime(1435): java.lang.RuntimeException: Unable to stop activity {de.abayev.theshapp/de.abayev.theshapp.EinkaufsListe}: java.lang.NullPointerException 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3461) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3515) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.app.ActivityThread.access$1400(ActivityThread.java:135) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1249) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.os.Handler.dispatchMessage(Handler.java:102) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.os.Looper.loop(Looper.java:136) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.app.ActivityThread.main(ActivityThread.java:5017) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at java.lang.reflect.Method.invoke(Method.java:515) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at dalvik.system.NativeStart.main(Native Method) 
10-07 15:00:24.100: E/AndroidRuntime(1435): Caused by: java.lang.NullPointerException 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.app.Activity.performStop(Activity.java:5388) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3456) 
10-07 15:00:24.100: E/AndroidRuntime(1435):  ... 11 more

來源

2014-10-07 Rome

調用super.onStop()自己其他地方比你onStop()是錯誤的，但不會導致異常。

你的問題

Caused by: java.lang.NullPointerException 
    at android.app.Activity.performStop(Activity.java:5388)

是由以下事實引起你提供的nullCursor到startManagingCursor()，特別是在onCreate()：

startManagingCursor(cursor_main);

其中尚未初始化cursor_main。

一起刪除startManagingCursor()。無論如何你都不應該將它用於新代碼。

來源

2014-10-07 19:16:59 laalto

哇，非常感謝。奇怪的是，我沒有看到我的自我！ – Rome 2014-10-07 19:26:53

 super.onStop();

親愛的大人沒有。不要從其他方法手動調用Activity生命週期回調方法。

致電finish()結束活動。

來源

2014-10-07 18:16:02 EpicPandaForce

:-D ..我只是很鄙視，我不知道，還有什麼要做。但它仍然沒有解決問題。 – Rome 2014-10-07 18:20:27

在這種情況下，錯誤在其他地方隱藏，您需要發佈更多的代碼，最好是'EinkaufsListe'類，並且如果您可以獲得幫助的非截斷版本的堆棧跟蹤。另外，SplashActivity會結束嗎？如果你終止了它，你如何阻止'SplashActivity'？ – EpicPandaForce 2014-10-07 18:22:34

如何獲得堆棧跟蹤版本？以及如何檢查活動是否結束？ – Rome 2014-10-07 18:29:55

使用這個代替的onkeydown：

@Override 
public void onBackPressed() { 

    Intent intent = new Intent(this, MainActivity.class); 
    startActivity(intent); 
    finish(); 
}

來源

2014-10-07 18:34:40

您是否重寫了其他生命週期方法？添加我的代碼而不是您的代碼後，堆棧跟蹤是什麼 – 2014-10-07 18:45:27

否我沒做過：這裏是跟蹤： 10-07 14：40：41.090：E/AndroidRuntime（1365）：致命例外：main 10-07 14：40：41.090：E/AndroidRuntime（1365）：進程：de.abayev.theshapp，PID：1365 10-07 14：40：41.090：E/AndroidRuntime（1365）：java .lang.RuntimeException：無法停止活動{de.abayev.theshapp/de.abayev.theshapp.EinkaufsListe}：java.lang.NullPointerException 10-07 14：40：41.090：E/AndroidRuntime（1365）：\t at android .app.ActivityThread.performDestroyActivity（ActivityThread.java:3461） 10-07 14：40：41.090：E/AndroidRuntime（1365）：\t at android.app.ActivityThread.handleDestroyActivity（ActivityThread.java） – Rome 2014-10-07 18:50:58

清理項目並運行並添加完整痕跡 – 2014-10-07 18:55:02

應用程序崩潰，當我按下返回按鈕

回答

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