java.lang.IllegalStateException: at android.view.ViewGroup.a

Question

应用程序在某些具有某些操作系统版本的设备上通过以下堆栈跟踪崩溃。我尝试了其他一些建议，它们都不起作用。我不知道崩溃发生在哪里。

视图组.java 添加视图内部问题

compileSdkVersion 28
minSdkVersion 17
targetSdkVersion 28

始终膨胀布局，如下所示：

if (mainView == null) {
     mainView = inflater.inflate(R.layout.fragment_main, container, false);
}

提交片段：

FragmentTransaction ft = fragmentManager.beginTransaction();
ft.setCustomAnimations(R.anim.fragment_slide_in_left, R.anim.fragment_slide_out_left, R.anim.fragment_slide_in_right, R.anim.fragment_slide_out_right);
ft.replace(R.id.main_content, fragment, fragment.getTagText());
ft.addToBackStack(fragment.getTagText());
ft.commit();

崩溃 1：

  java.lang.IllegalStateException: 
  at android.view.ViewGroup.addViewInner (ViewGroup.java:5008)
  at android.view.ViewGroup.addView (ViewGroup.java:4833)
  at android.view.ViewGroup.addView (ViewGroup.java:4773)
  at android.view.ViewGroup.addView (ViewGroup.java:4746)
  at android.support.v4.app.FragmentManagerImpl.moveToState (FragmentManagerImpl.java:1466)
  at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState (FragmentManagerImpl.java:1784)
  at android.support.v4.app.FragmentManagerImpl.moveToState (FragmentManagerImpl.java:1852)
  at android.support.v4.app.BackStackRecord.executePopOps (BackStackRecord.java:860)
  at android.support.v4.app.FragmentManagerImpl.executeOps (FragmentManagerImpl.java:2622)
  at android.support.v4.app.FragmentManagerImpl.executeOpsTogether (FragmentManagerImpl.java:2411)
  at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute (FragmentManagerImpl.java:2366)
  at android.support.v4.app.FragmentManagerImpl.execPendingActions (FragmentManagerImpl.java:2273)
  at android.support.v4.app.FragmentManagerImpl$1.run (FragmentManagerImpl.java:733)
  at android.os.Handler.handleCallback (Handler.java:790)
  at android.os.Handler.dispatchMessage (Handler.java:99)
  at android.os.Looper.loop (Looper.java:171)
  at android.app.ActivityThread.main (ActivityThread.java:6656)
  at java.lang.reflect.Method.invoke (Method.java)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:547)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:873)

崩溃 2：

java.lang.IllegalStateException: 
  at android.view.ViewGroup.addViewInner (ViewGroup.java:5122)
  at android.view.ViewGroup.addView (ViewGroup.java:4953)
  at android.view.ViewGroup.addView (ViewGroup.java:4893)
  at android.view.ViewGroup.addView (ViewGroup.java:4866)
  at android.support.v4.app.FragmentManagerImpl.moveToState (FragmentManagerImpl.java:1466)
  at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState (FragmentManagerImpl.java:1784)
  at android.support.v4.app.FragmentManagerImpl.moveToState (FragmentManagerImpl.java:1852)
  at android.support.v4.app.BackStackRecord.executePopOps (BackStackRecord.java:860)
  at android.support.v4.app.FragmentManagerImpl.executeOps (FragmentManagerImpl.java:2622)
  at android.support.v4.app.FragmentManagerImpl.executeOpsTogether (FragmentManagerImpl.java:2411)
  at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute (FragmentManagerImpl.java:2366)
  at android.support.v4.app.FragmentManagerImpl.execPendingActions (FragmentManagerImpl.java:2273)
  at android.support.v4.app.FragmentManagerImpl$1.run (FragmentManagerImpl.java:733)
  at android.os.Handler.handleCallback (Handler.java:789)
  at android.os.Handler.dispatchMessage (Handler.java:98)
  at android.os.Looper.loop (Looper.java:164)
  at android.app.ActivityThread.main (ActivityThread.java:6940)
  at java.lang.reflect.Method.invoke (Method.java)
  at com.android.internal.os.Zygote$MethodAndArgsCaller.run (Zygote.java:327)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1374)

如何修复此崩溃？

Answer 1

删除空检查并在onCreateView中膨胀视图。

当您返回旧视图时(mainView != null)片段会尝试将其再次添加到视图层次结构中。引发异常是因为旧视图已具有父视图，无法再次添加。

ViewGroup.addViewInner的来源：

    if (child.getParent() != null) {
        throw new IllegalStateException("The specified child already has a parent. " +
                "You must call removeView() on the child's parent first.");
    }