为什么我在 Android 中收到“无法删除附加到不同 FragmentManager 的 Fragment”？

Question

我正在尝试删除片段，但很少在 Crashlytics 上看到错误 java.lang.IllegalStateException：无法删除附加到不同 FragmentManager 的片段。

我有一个单独的片段用于获取用户的当前位置。我使用下面的代码打开片段。

private void openLocationFragment() {
    LocationFragment locationFragment = LocationFragment.newInstance();
    FragmentManager fragmentManager = getSupportFragmentManager();
    fragmentManager.beginTransaction()
            .replace(R.id.fragmentContainer, locationFragment, "location_fragment")
            .commitAllowingStateLoss();
}

现在，在片段中，一旦我获得位置更新，我就会使用附加到活动的侦听器调用 onLocationFetched 方法。

在此方法中，我使用以下代码删除片段。

@Override
public void onLocationFetched(Location location) {
    FragmentManager fragmentManager = getSupportFragmentManager();
    LocationFragment locationFragment = (LocationFragment) fragmentManager.findFragmentByTag("location_fragment");
    if (locationFragment != null) {
        fragmentManager.beginTransaction()
                .remove(locationFragment) // Here is the exception
                .commitAllowingStateLoss();
    }
    if(location == null){
        fetchUserDetails();
    }else
        fetchCity(location);
}

堆栈跟踪：

Fatal Exception: **java.lang.IllegalStateException: Cannot remove Fragment attached to a different FragmentManager.** 

Fragment LocationFragment{32a2ed0 (d41fc341-baf2-4266-948a-866fba7e57b5) id=0x7f09028b location_fragment} is already attached to a FragmentManager.
       at androidx.fragment.app.BackStackRecord.remove(BackStackRecord.java:316)
       at com.avail.easyloans.feature.marketplace.activities.ActivityMarketplace.onFragmentFetched(ActivityMarketplace.java:909)
       at com.avail.easyloans.base.fragments.LocationFragment.sendLocationToClient(LocationFragment.java:192)
       at com.avail.easyloans.base.fragments.LocationFragment.access$000(LocationFragment.java:46)
       at com.avail.easyloans.base.fragments.LocationFragment$4.onSuccess(LocationFragment.java:220)
       at com.avail.easyloans.base.fragments.LocationFragment$4.onSuccess(LocationFragment.java:214)
       at com.google.android.gms.tasks.zzn.run(zzn.java:4)
       at android.os.Handler.handleCallback(Handler.java:836)
       at android.os.Handler.dispatchMessage(Handler.java:103)
       at android.os.Looper.loop(Looper.java:203)
       at android.app.ActivityThread.main(ActivityThread.java:6339)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1084)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:945)

我在这里做错了什么？

Answer 1

我希望每个人Activity都有责任维护自己的Fragments。这意味着如果您尝试访问的 Fragment 与另一个ActivityFragment关联FragmentManager，那么您的应用程序将失败。

我可以想出几种方法来解决这个问题，具体取决于您想要的行为。如果您不介意让两个LocationFragments 在两个单独的活动中拥有自己单独的生命周期，您可以findFragmentById()在您的FragmentManager. IE：

private void openLocationFragment() {
    FragmentManager fragmentManager = getSupportFragmentManager();
    final Fragment current = fragmentManager.findFragmentById(R.id.fragmentContainer);
    if(current == null || !(current instanceof LocationFragment)) {
        fragmentManager.beginTransaction()
            .replace(R.id.fragmentContainer, LocationFragment.newInstance())
            .commitAllowingStateLoss();
    }
}

并在您的其他活动中执行相同的操作。Activity或者，您可以调用托管LocationFragmentin的其他主机onLocationFetched()