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我最近在我的程序中收到了一個崩潰。使用logCat我確定崩潰是由於我的應用程序正在恢復時主要活動中的onRestoreInstanceState()中的代碼。 logcat的文件：在onRestoreInstanceState中綁定null？
07-23 16:27:01.927 I/ActivityManager( 390): START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.myapp/.MainActivity bnds=[1184,809][1376,1001]} from pid 30666
07-23 16:27:01.997 I/ActivityManager( 390): Start proc com.myapp for activity com.myapp/.MainActivity: pid=31007 uid=10070 gids={50070, 1028}
07-23 16:27:02.137 E/AndroidRuntime(31007): FATAL EXCEPTION: main
07-23 16:27:02.137 E/AndroidRuntime(31007): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp/com.myapp.MainActivity}: java.lang.ClassCastException: android.os.Parcelable[] cannot be cast to com.myapp.Panel[]
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.app.ActivityThread.access$600(ActivityThread.java:141)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.os.Handler.dispatchMessage(Handler.java:99)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.os.Looper.loop(Looper.java:137)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.app.ActivityThread.main(ActivityThread.java:5041)
07-23 16:27:02.137 E/AndroidRuntime(31007): at java.lang.reflect.Method.invokeNative(Native Method)
07-23 16:27:02.137 E/AndroidRuntime(31007): at java.lang.reflect.Method.invoke(Method.java:511)
07-23 16:27:02.137 E/AndroidRuntime(31007): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-23 16:27:02.137 E/AndroidRuntime(31007): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-23 16:27:02.137 E/AndroidRuntime(31007): at dalvik.system.NativeStart.main(Native Method)
07-23 16:27:02.137 E/AndroidRuntime(31007): Caused by: java.lang.ClassCastException: android.os.Parcelable[] cannot be cast to com.myapp.Panel[]
07-23 16:27:02.137 E/AndroidRuntime(31007): at com.myapp.MainActivity.onRestoreInstanceState(MainActivity.java:177)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.app.Activity.performRestoreInstanceState(Activity.java:910)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.app.Instrumentation.callActivityOnRestoreInstanceState(Instrumentation.java:1131)
07-23 16:27:02.137 E/AndroidRuntime(31007): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2158)
07-23 16:27:02.137 E/AndroidRuntime(31007): ... 11 more
07-23 16:27:02.167 W/ActivityManager( 390): Force finishing activity com.myapp/.MainActivity
所述的碰撞發生在在下面的onRestoreInstanceState方法線mPanels = (Panel[]) inState.getParcelableArray("panelParcel");。
這種方法已經穩健地爲我工作，直到此崩潰，我試圖找出爲什麼inState似乎沒有，我已經保存在它的對象（面板）的陣列。我很困惑，因爲它好像inState不包含我保存到它的panelParcel。
我從this question看到我通常應該使用onCreate代替onRestoreInstanceState，但我很想知道爲什麼這難道不中難得一遇的工作，也許我不完全瞭解一些有關的活動的生命週期？
代碼都保存和恢復實例狀態：
@Override
public void onSaveInstanceState(@NotNull Bundle outState)
{
Log.d("panelCreation", "onSaveInstanceState Called");
super.onSaveInstanceState(outState);
// save the current panel state
outState.putParcelableArray("panelParcel", mPanels);
}
@Override
public void onRestoreInstanceState(Bundle inState)
{
Log.d("panelCreation", "onsState Called");
super.onRestoreInstanceState(inState);
// Note getParcelable returns a *new* array, so we must setup the drawer listener after this
mPanels = (Panel[]) inState.getParcelableArray("panelParcel");
// set up the drawer's list view with items and click listener
mDrawerList.setAdapter(new PanelArrayAdapter(this,
R.layout.drawer_list_item, mPanels));
refreshDrawerListChecked();
// Forces the Adapter to redraw the view to ensure color stylings are applied
((PanelArrayAdapter)mDrawerList.getAdapter()).notifyDataSetChanged();
}
請記住，這絕大多數時間都適用 - 我在工作中剛剛獲得「幸運」的時間嗎？ – CrimsonX
我想你可能是正確的 - 將調查，這篇文章看起來是相當有益的，類似我的問題：http://stackoverflow.com/questions/10071502/read-writing-arrays-of-parcelable-objects – CrimsonX
正如我一般來說，除非編譯器/解釋器「知道」SuperType []'實際上是DerivedType []'，否則不能將'SuperType []'強制轉換爲'DerivedType []'。在你的情況下，解釋器不知道反序列化數組是'Panel'的數組。所以你需要轉換數組的每個元素或使用'Arrays.copyOf（a，a.length，Panel []。class）;''哪裏'a'是'Parcelable [] a = inState.getParcelableArray（「panelParcel」）' 。 – JustAnotherCoder