如何清除Android碎片返回堆栈而不恢复中间碎片

Question

我需要清除back堆栈中的所有片段。

问题是我需要确保在某个时间点，堆栈已被成功清除，并且之后不会恢复弹出的碎片。

部分片段显示与当前登录用户相关的内容。现在，如果用户决定注销，我想要清除堆栈，注销用户，并将应用程序过渡到初始片段。问题是，堆栈弹出延迟，在我退出后，一些用户相关的片段试图恢复并要求用户配置文件数据。如果没有登录用户，底层API将抛出异常。因此，片段崩溃，因为它不应该在这种状态下使用。

我试过很多方法:

@Override
public void onSignOutConfirmed() {
    Log.d(TAG, "onSignOutConfirmed");
    getSupportFragmentManager().popBackStackImmediate(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
    Log.d(TAG, "onSignOutConfirmed - signing out");
    UserProfileService.signOut();
    Analytics.trackEvent(EventType.SIGN_OUT);
    showStartupScreen();
}

或

@Override
public void onSignOutConfirmed() {
    Log.d(TAG, "onSignOutConfirmed");
    FragmentManager fm = getSupportFragmentManager();
    int backStackCount = fm.getBackStackEntryCount();
    while(backStackCount-- != 0) {
        fm.popBackStackImmediate();
    }
    Log.d(TAG, "onSignOutConfirmed - signing out");
    UserProfileService.signOut();
    Analytics.trackEvent(EventType.SIGN_OUT);
    showStartupScreen();
}

日志显示，当我调用UserProfileService.signOut()时，片段仍在处理其生命周期方法。当片段暂停时，检索其中一个片段的概要数据的AsyncTask被取消(带有中断)。但是片段暂停得太晚了。

错误并不总是命中。但大多数情况下，它击中三星S2 (Android 4.1.2)。

06-09 19:46:54.760 D/com.myapp.application.MainActivity( 4562): **onSignOutConfirmed**
06-09 19:46:54.765 D/com.myapp.application.screens.main.MainFragment( 4562): onCreateView
06-09 19:46:54.826 D/com.myapp.application.screens.main.MainFragment( 4562): onCreateAnimation (transit 0, enter true, nextAnim 0)
06-09 19:46:54.831 D/com.myapp.application.screens.main.TranscriptionsFragment( 4562): onCreateView
06-09 19:46:54.856 D/com.myapp.application.screens.main.MainFragment( 4562): onResume
06-09 19:46:54.856 D/com.myapp.application.screens.main.TranscriptionsFragment( 4562): **onResume**
06-09 19:46:54.866 D/com.myapp.application.MainActivity( 4562): **onSignOutConfirmed - signing out**
06-09 19:46:54.876 D/myappDB( 4562): Application settings: id 1.
06-09 19:46:54.876 D/myappDB( 4562): Application settings (id 1): updated, [_activeProfileId] = [null].
06-09 19:46:54.916 D/myappDB( 4562): Application settings: active user profile null.
06-09 19:46:54.941 D/myappDB( 4562): Application settings: active user profile null.
06-09 19:46:54.951 D/com.myapp.application.screens.main.TranscriptionsFragment( 4562): **onPause**
06-09 19:46:54.951 D/com.myapp.application.screens.main.MainFragment( 4562): onPause
06-09 19:46:54.961 D/com.myapp.application.screens.main.TranscriptionsFragment( 4562): onDestroyView
06-09 19:46:54.961 D/com.myapp.application.screens.main.MainFragment( 4562): onDestroyView
06-09 19:46:54.961 D/com.myapp.application.screens.main.MainFragment( 4562): onCreateAnimation (transit 0, enter false, nextAnim 0)
06-09 19:46:55.381 E/AndroidRuntime( 4562):     at com.myapp.application.impls.sqlite.SQLiteApplicationSettingsPersistance.getAndCheckActiveUserProfileId(SQLiteApplicationSettingsPersistance.java:421)
06-09 19:46:55.381 E/AndroidRuntime( 4562):     at com.myapp.application.impls.sqlite.SQLiteTranscriptionPersistance.getTranscriptionStats(SQLiteTranscriptionPersistance.java:54)
06-09 19:46:55.381 E/AndroidRuntime( 4562):     at com.myapp.application.impls.finders.TranscriptionListFinder.getTranscriptions(TranscriptionListFinder.java:45)
06-09 19:46:55.381 E/AndroidRuntime( 4562):     at com.myapp.application.screens.main.TranscriptionsFragment$RetrieveTranscriptionsAsyncTask.doInBackground(TranscriptionsFragment.java:244)
06-09 19:46:55.381 E/AndroidRuntime( 4562):     at com.myapp.application.screens.main.TranscriptionsFragment$RetrieveTranscriptionsAsyncTask.doInBackground(TranscriptionsFragment.java:241)
06-09 19:46:55.421 D/com.myapp.application.screens.main.TranscriptionsFragment( 4562): onDetach

Answer 1

试试这个:

private void clearFragmentBackStack() {
    FragmentManager fm = getSupportFragmentManager();
    for(int i = 0; i < fm.getBackStackEntryCount(); ++i) {
        fm.popBackStack();
    }
}