在回调 viewpager 片段后按收到此错误您必须首先在孩子的父母上调用 removeView()

Question

我正在用 Fragment2 替换其子 Fragment1 中的 Fragment1（具有视图寻呼机）。

 Fragment fragment = Childfragment1.this.getParentFragment();
    FragmentManager fragmentManager = fragment.getFragmentManager();

    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    Fragment2 Fragment2 = new Fragment2();


    fragmentTransaction.replace(R.id.cat_container, Fragment2 , "Fragment2 ");
    fragmentTransaction.addToBackStack("Fragment2 ");
    fragmentTransaction.commit();

它工作正常，但是当按下返回按钮时它会因错误而崩溃

指定的孩子已经有一个父母。您必须首先在 super.onBackPressed(); 上调用子父级的 removeView()；线

@Override
public void onBackPressed() {


    int count = getFragmentManager().getBackStackEntryCount();


    if (count == 0) {


        super.onBackPressed();


    } else {


        getFragmentManager().popBackStack();

    }




}

这是我的 logcat 错误

 java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
    at android.view.ViewGroup.addViewInner(ViewGroup.java:5038)
    at android.view.ViewGroup.addView(ViewGroup.java:4869)
    at androidx.viewpager.widget.ViewPager.addView(ViewPager.java:1485)
    at android.view.ViewGroup.addView(ViewGroup.java:4809)
    at android.view.ViewGroup.addView(ViewGroup.java:4782)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:887)
    at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
    at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2659)
    at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java:2613)
    at androidx.fragment.app.Fragment.performActivityCreated(Fragment.java:2624)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:904)
    at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
    at androidx.fragment.app.BackStackRecord.executePopOps(BackStackRecord.java:500)
    at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2076)
    at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869)
    at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
    at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:310)
    at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:253)
    at androidx.fragment.app.FragmentManagerImpl.handleOnBackPressed(FragmentManagerImpl.java:233)
    at androidx.fragment.app.FragmentManagerImpl$1.handleOnBackPressed(FragmentManagerImpl.java:108)
    at androidx.activity.OnBackPressedDispatcher.onBackPressed(OnBackPressedDispatcher.java:189)
    at androidx.activity.ComponentActivity.onBackPressed(ComponentActivity.java:286)
    at in.arkemtech.offersoffer.main_freg.Main2Activity.onBackPressed(Main2Activity.java:466)
    at android.app.Activity.onKeyUp(Activity.java:3147)
    at android.view.KeyEvent.dispatch(KeyEvent.java:2744)
    at android.app.Activity.dispatchKeyEvent(Activity.java:3430)
    at androidx.core.app.ComponentActivity.superDispatchKeyEvent(ComponentActivity.java:115)
    at androidx.core.view.KeyEventDispatcher.dispatchKeyEvent(KeyEventDispatcher.java:84)
    at androidx.core.app.ComponentActivity.dispatchKeyEvent(ComponentActivity.java:133)
    at androidx.appcompat.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:558)
    at androidx.appcompat.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:59)
    at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.dispatchKeyEvent(AppCompatDelegateImpl.java:2814)
    at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:346)
    at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:5213)
    at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:5081)
    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4600)
    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4653)
    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4619)
    at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4759)
    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4627)
    at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4816)
    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4600)
    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4653)
    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4619)
    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:

Answer 1

这是一个更新的答案，因为我预测另一个修复会导致连锁问题：

当我将 com.google.android.material 从 1.1.0-alpha05 升级到 1.2.0-alpha04 时，这是在以前工作的应用程序中触发的，一些实验表明 1.1.0-alpha07 以上的任何内容都有问题。因此，如果您不喜欢 alpha 版本，请尝试恢复到此版本或更早版本

implementation 'com.google.android.material:material:1.1.0-alpha07'

我仍然不确定这是否真的是 com.google.android.material 中的错误，或者升级后的库是否发现了我代码中的潜在缺陷。

---

下面的旧答案，因为它可能仍然为某人提供有用的线索：

在我的 Fragments onCreateView 中，我将存储创建的视图

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    if (searchView == null) {
        searchView = super.onCreateView(inflater, container, savedInstanceState)
        ...
    }
    return searchView
}

我删除了执行此操作的代码，这解决了问题。

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    val searchView = super.onCreateView(inflater, container, savedInstanceState)
    ...
    return searchView
}

我现在正试图记住为什么我首先要隐藏视图，当然我很快就会发现我的应用程序中的其他东西现在坏了。

Answer 2

您应该使用getParentFragmentManager（甚至getActivity().getSupportFragmentManager()）来获取FragmentManager 进行此交易。