13

私はAndroidサポートライブラリv4リビジョン11を使用しており、時々、スタックトレースを以下に示します。最近のローンチが原因だと思うので、アクセスしようとしているモデルはnullです。とにかく、このトレースは、アクティビティが破棄されているときにonCreateViewが呼び出される理由と、そのようなケースを処理するための最良の方法は何であるかを疑問に思いました。

java.lang.NullPointerException
    at com.example.dialogs.ExampleDialogFragment.onCreateView(ExampleDialogFragment.java:53)
    at android.support.v4.app.Fragment.performCreateView(Fragment.java:1460)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:911)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1070)
    at android.support.v4.app.FragmentManagerImpl.dispatchReallyStop(FragmentManager.java:1888)
    at android.support.v4.app.FragmentActivity.onReallyStop(FragmentActivity.java:787)
    at android.support.v4.app.FragmentActivity.doReallyStop(FragmentActivity.java:764)
    at android.support.v4.app.FragmentActivity.onDestroy(FragmentActivity.java:322)
    at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3642)
    at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3673)
    at android.app.ActivityThread.access$2900(ActivityThread.java:125)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:123)
    at android.app.ActivityThread.main(ActivityThread.java:4627)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:521)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
    at dalvik.system.NativeStart.main(Native Method)

onResume()クラッシュ後、バックスタックからのアクティビティが再開された後、モデルがアクティビティで有効かどうかを確認しonStart()ますonCreate(Bundle savedInstanceState)。モデルが有効でない場合は、そこから別のアクティビティを開始しますFLAG_ACTIVITY_NO_HISTORY。finish()return;

@Override
public void onResume() {        
    Model cm = Application.getModel();
    final boolean isModelAvailable = cm != null;
    if (!isModelAvailable) {
        Intent restartIntent = IntentUtil.intentForAction(Constants.INTENT_RESTART);
        restartIntent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
        startActivity(restartIntent);
        finish();
        super.onResume();
        return;
    } else {

    }

INTENT_RESTARTアクティビティがモデルの再初期化で終了した後、フラグFLAG_ACTIVITY_CLEAR_TOPを使用してアクティビティを開始します。このアクティビティは、フラグメントにトランザクションをコミットします。FirstFragment

でログを参照してくださいFragmentManager.enableDebugLogging(true);。

05-13 13:24:53.051: V/FragmentManager(7468): Commit: BackStackEntry{40710fa0}
05-13 13:24:53.111: V/FragmentManager(7468): Commit: BackStackEntry{40771e78}
05-13 13:24:53.151: V/FragmentManager(7468): Run: BackStackEntry{40710fa0}
05-13 13:24:53.151: V/FragmentManager(7468): add: RetainFragment{4077d048 app_ImageCache}
05-13 13:24:53.151: V/FragmentManager(7468): Allocated fragment index RetainFragment{4077d048 #0 app_ImageCache}
05-13 13:24:53.151: V/FragmentManager(7468): moveto CREATED: RetainFragment{4077d048 #0 app_ImageCache}
05-13 13:24:53.151: V/FragmentManager(7468): moveto ACTIVITY_CREATED: RetainFragment{4077d048 #0 app_ImageCache}
05-13 13:24:53.151: V/FragmentManager(7468): Run: BackStackEntry{40771e78}
05-13 13:24:53.151: V/FragmentManager(7468): add: FirstFragment{4077dfa8 id=0x7f04000d}
05-13 13:24:53.151: V/FragmentManager(7468): Allocated fragment index FirstFragment{4077dfa8 #1 id=0x7f04000d}
05-13 13:24:53.151: V/FragmentManager(7468): moveto CREATED: FirstFragment{4077dfa8 #1 id=0x7f04000d}
05-13 13:24:53.151: V/FragmentManager(7468): moveto ACTIVITY_CREATED: FirstFragment{4077dfa8 #1 id=0x7f04000d}
05-13 13:24:53.791: V/FragmentManager(7468): moveto STARTED: RetainFragment{4077d048 #0 app_ImageCache}
05-13 13:24:53.791: V/FragmentManager(7468): moveto STARTED: FirstFragment{4077dfa8 #1 id=0x7f04000d}
05-13 13:24:53.811: V/FragmentManager(7468): moveto RESUMED: RetainFragment{4077d048 #0 app_ImageCache}
05-13 13:24:53.811: V/FragmentManager(7468): moveto RESUMED: FirstFragment{4077dfa8 #1 id=0x7f04000d}

05-13 13:25:58.414: V/FragmentManager(7468): Commit: BackStackEntry{40727530}
05-13 13:25:58.434: V/FragmentManager(7468): Run: BackStackEntry{4078fe00}
05-13 13:25:58.434: V/FragmentManager(7468): add: RetainFragment{4076f1b0 app_ImageCache}
05-13 13:25:58.434: V/FragmentManager(7468): Allocated fragment index RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:25:58.434: V/FragmentManager(7468): moveto CREATED: RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:25:58.434: V/FragmentManager(7468): moveto ACTIVITY_CREATED: RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:25:58.434: V/FragmentManager(7468): Run: BackStackEntry{40727530}
05-13 13:25:58.434: V/FragmentManager(7468): add: SecondFragment{40713c28 id=0x7f04000d}
05-13 13:25:58.434: V/FragmentManager(7468): Allocated fragment index SecondFragment{40713c28 #1 id=0x7f04000d}
05-13 13:25:58.434: V/FragmentManager(7468): moveto CREATED: SecondFragment{40713c28 #1 id=0x7f04000d}
05-13 13:25:58.434: V/FragmentManager(7468): moveto ACTIVITY_CREATED: SecondFragment{40713c28 #1 id=0x7f04000d}
05-13 13:25:58.545: V/FragmentManager(7468): moveto STARTED: RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:25:58.545: V/FragmentManager(7468): moveto STARTED: SecondFragment{40713c28 #1 id=0x7f04000d}
05-13 13:25:58.565: V/FragmentManager(7468): moveto RESUMED: RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:25:58.565: V/FragmentManager(7468): moveto RESUMED: SecondFragment{40713c28 #1 id=0x7f04000d}

05-13 13:26:02.338: V/FragmentManager(7468): Saved state of RetainFragment{4077d048 #0 app_ImageCache}: null
05-13 13:26:02.338: V/FragmentManager(7468): Saved state of FirstFragment{4077dfa8 #1 id=0x7f04000d}: Bundle[{android:view_state=android.util.SparseArray@40b15b60}]
05-13 13:26:02.338: V/FragmentManager(7468): saveAllState: adding fragment #0: RetainFragment{4077d048 #0 app_ImageCache}
05-13 13:26:02.338: V/FragmentManager(7468): saveAllState: adding fragment #1: FirstFragment{4077dfa8 #1 id=0x7f04000d}
05-13 13:26:02.348: V/FragmentManager(7468): movefrom STARTED: RetainFragment{4077d048 #0 app_ImageCache}
05-13 13:26:02.348: V/FragmentManager(7468): movefrom STARTED: FirstFragment{4077dfa8 #1 id=0x7f04000d}
05-13 13:26:02.358: V/FragmentManager(7468): movefrom STOPPED: RetainFragment{4077d048 #0 app_ImageCache}
05-13 13:26:02.358: V/FragmentManager(7468): movefrom STOPPED: FirstFragment{4077dfa8 #1 id=0x7f04000d}
05-13 13:27:15.219: V/FragmentManager(7468): movefrom RESUMED: RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:27:15.219: V/FragmentManager(7468): movefrom RESUMED: SecondFragment{40713c28 #1 id=0x7f04000d}

05-13 13:27:15.239: V/FragmentManager(7468): Commit: BackStackEntry{40a8a6d0}
05-13 13:27:15.259: V/FragmentManager(7468): Commit: BackStackEntry{40a90190}

05-13 13:27:15.279: V/FragmentManager(7468): Run: BackStackEntry{40a8a6d0}
05-13 13:27:15.279: V/FragmentManager(7468): add: RetainFragment{40a7fdf0 app_ImageCache}
05-13 13:27:15.279: V/FragmentManager(7468): Allocated fragment index RetainFragment{40a7fdf0 #0 app_ImageCache}
05-13 13:27:15.279: V/FragmentManager(7468): moveto CREATED: RetainFragment{40a7fdf0 #0 app_ImageCache}
05-13 13:27:15.279: V/FragmentManager(7468): moveto ACTIVITY_CREATED: RetainFragment{40a7fdf0 #0 app_ImageCache}
05-13 13:27:15.279: V/FragmentManager(7468): Run: BackStackEntry{40a90190}
05-13 13:27:15.279: V/FragmentManager(7468): add: ThirdFragment{406c2308 id=0x7f04000d}
05-13 13:27:15.279: V/FragmentManager(7468): Allocated fragment index ThirdFragment{406c2308 #1 id=0x7f04000d}
05-13 13:27:15.289: V/FragmentManager(7468): moveto CREATED: ThirdFragment{406c2308 #1 id=0x7f04000d}
05-13 13:27:15.289: V/FragmentManager(7468): moveto ACTIVITY_CREATED: ThirdFragment{406c2308 #1 id=0x7f04000d}
05-13 13:27:15.410: V/FragmentManager(7468): moveto STARTED: RetainFragment{40a7fdf0 #0 app_ImageCache}
05-13 13:27:15.410: V/FragmentManager(7468): moveto STARTED: ThirdFragment{406c2308 #1 id=0x7f04000d}
05-13 13:27:15.430: V/FragmentManager(7468): moveto RESUMED: RetainFragment{40a7fdf0 #0 app_ImageCache}
05-13 13:27:15.430: V/FragmentManager(7468): moveto RESUMED: ThirdFragment{406c2308 #1 id=0x7f04000d}
05-13 13:27:15.810: V/FragmentManager(7468): Saved state of RetainFragment{4076f1b0 #0 app_ImageCache}: null
05-13 13:27:15.810: V/FragmentManager(7468): Saved state of SecondFragment{40713c28 #1 id=0x7f04000d}: Bundle[{android:view_state=android.util.SparseArray@40aa62c0}]
05-13 13:27:15.810: V/FragmentManager(7468): saveAllState: adding fragment #0: RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:27:15.810: V/FragmentManager(7468): saveAllState: adding fragment #1: SecondFragment{40713c28 #1 id=0x7f04000d}
05-13 13:27:15.810: V/FragmentManager(7468): movefrom STARTED: RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:27:15.810: V/FragmentManager(7468): movefrom STARTED: SecondFragment{40713c28 #1 id=0x7f04000d}
05-13 13:27:15.820: V/FragmentManager(7468): movefrom STOPPED: RetainFragment{4076f1b0 #0 app_ImageCache}
05-13 13:27:15.820: V/FragmentManager(7468): movefrom STOPPED: SecondFragment{40713c28 #1 id=0x7f04000d}


// Here I'm waiting for a while to make sure Android has enough time to do anything it wants, then I press a button gorse-closing the app  
05-13 13:27:59.783: D/AndroidRuntime(7468): Shutting down VM


05-13 13:28:14.928: V/FragmentManager(7523): Instantiated fragment RetainFragment{406cde80 #0 app_ImageCache}
05-13 13:28:14.938: V/FragmentManager(7523): restoreAllState: active #0: RetainFragment{406cde80 #0 app_ImageCache}
05-13 13:28:14.938: V/FragmentManager(7523): Instantiated fragment FirstFragment{406d8410 #1 id=0x7f04000d}
05-13 13:28:14.938: V/FragmentManager(7523): restoreAllState: active #1: FirstFragment{406d8410 #1 id=0x7f04000d}
05-13 13:28:14.938: V/FragmentManager(7523): restoreAllState: added #0: RetainFragment{406cde80 #0 app_ImageCache}
05-13 13:28:14.938: V/FragmentManager(7523): restoreAllState: added #1: FirstFragment{406d8410 #1 id=0x7f04000d}
05-13 13:28:14.938: V/FragmentManager(7523): moveto CREATED: RetainFragment{406cde80 #0 app_ImageCache}
05-13 13:28:14.938: V/FragmentManager(7523): moveto CREATED: FirstFragment{406d8410 #1 id=0x7f04000d}

05-13 13:28:15.128: V/msm8660.gralloc(7523): PmemUserspaceAllocator::PmemUserspaceAllocator(PmemUserspaceAllocator::Deps&, PmemUserspaceAllocator::Deps::Allocator&, const char*) begin
05-13 13:28:15.138: V/msm8660.gralloc(7523): PmemUserspaceAllocator::PmemUserspaceAllocator(PmemUserspaceAllocator::Deps&, PmemUserspaceAllocator::Deps::Allocator&, const char*) end
05-13 13:28:15.138: V/msm8660.gralloc(7523): PmemKernelAllocator::PmemKernelAllocator(PmemKernelAllocator::Deps&) begin
05-13 13:28:15.138: V/msm8660.gralloc(7523): PmemKernelAllocator::PmemKernelAllocator(PmemKernelAllocator::Deps&) end

05-13 13:28:15.408: V/FragmentManager(7523): moveto ACTIVITY_CREATED: RetainFragment{406cde80 #0 app_ImageCache}
05-13 13:28:15.408: V/FragmentManager(7523): moveto ACTIVITY_CREATED: FirstFragment{406d8410 #1 id=0x7f04000d}

java.lang.RuntimeException: Unable to destroy activity {com.myapp/com.myapp.activity.FirstFragment}: java.lang.NullPointerException

05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3272)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3299)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.app.ActivityThread.access$2100(ActivityThread.java:134)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1143)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.os.Looper.loop(Looper.java:152)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.app.ActivityThread.main(ActivityThread.java:4606)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at java.lang.reflect.Method.invokeNative(Native Method)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at java.lang.reflect.Method.invoke(Method.java:491)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at dalvik.system.NativeStart.main(Native Method)

// see the original question log, it is quite the same
05-13 13:35:41.824: E/AndroidRuntime(7691): Caused by: java.lang.NullPointerException
05-13 13:35:41.824: E/AndroidRuntime(7691):     at com.myapp/com.myapp.activity.FirstFragment.onCreateView(FirstFragment.java:41)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1460)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:911)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1070)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.support.v4.app.FragmentManagerImpl.dispatchReallyStop(FragmentManager.java:1888)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.support.v4.app.FragmentActivity.onReallyStop(FragmentActivity.java:787)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.support.v4.app.FragmentActivity.doReallyStop(FragmentActivity.java:764)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.support.v4.app.FragmentActivity.onDestroy(FragmentActivity.java:322)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at com.myapp.activity.FragmentsContainerActivity.onDestroy(FragmentsContainerActivity.java:806)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.app.Activity.performDestroy(Activity.java:4662)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.app.Instrumentation.callActivityOnDestroy(Instrumentation.java:1113)
05-13 13:35:41.824: E/AndroidRuntime(7691):     at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3255)
05-13 13:35:41.824: E/AndroidRuntime(7691):     ... 11 more

の行＃806FragmentsContainerActivityはsuper.onDestroy();：

@Override
public void onDestroy() {
    try {
        unregister(receiver);
    } catch (Exception e) {
    }
    super.onDestroy();
4

4 に答える 4

7

メソッドを参照するコード サンプルのガイドに従って、次のことを行う必要があります。onResume

常に最初にスーパークラス メソッドを呼び出す

super.onResume();つまり、最初に右に置く必要があります。それが問題に違いない。

実行中の現在のコードでは、停止するように指示されている FragmentActivity (つまりfinish) とその後に指示されている FragmentActivity を混同していresumeます。アクティビティのライフ サイクルで「正当」ではないライフ サイクル。ライフサイクルはアクティビティのライフサイクルから呼び出されるため、フラグメントは直接影響を受けます。アクティビティが終了から再開された場合は、フラグメントが終了/破棄から再開 (onCreateView) を通過したことを意味します。

于 2013-05-13T21:31:26.520 に答える