读 http://chris-alexander.co.uk/on-engineering/dev/android-fragments-within-fragments/

篇文章。 fragment. isresume()检查帮助我在onDestroyView w/o使用onSaveInstanceState方法。

I noticed something very interesting. I have in my app the option to open the phone's gallery and the device asks what app to use, there I click on the gray area away from the dialog and saw this issue. I noticed how my activity goes from onPause, onSaveInstanceState back to onResume, it doesn't happen to visit onCreateView. I am doing transactions at onResume. So what I ended up doing is setting a flag being negated onPause, but being true onCreateView. if the flag is true onResume then do onCommit, otherwise commitAllowingStateLoss. I could go on and waste so much time but I wanted to check the lifecycle. I have a device which is sdkversion 23, and I don't get this issue, but I have another one which is 21, and there I see it.

当一个Fragment或AppCompatActivity的状态通过onSaveInstanceState()保存时，它的UI被认为是不可变的，直到ON_START被调用。在保存状态后尝试修改UI可能会导致应用程序导航状态的不一致，这就是为什么FragmentManager会抛出异常，如果应用程序在保存状态后运行FragmentTransaction。参见commit()了解详细信息。

LiveData通过避免在观察者的关联生命周期至少不是STARTED时调用它的观察者来避免这种边缘情况。在幕后，它在决定调用其观察者之前调用isAtLeast()。

这是我迄今为止遇到的最愚蠢的错误。我有一个片段应用程序工作完美的API < 11，并强制关闭API > 11。

我真的不知道他们在saveInstance调用的活动生命周期内改变了什么，但我在这里是我如何解决这个问题的:

@Override
protected void onSaveInstanceState(Bundle outState) {
    //No call for super(). Bug on API Level > 11.
}

我只是不调用.super()，一切都很好。我希望这将为您节省一些时间。

编辑:经过进一步研究，这是支持包中的一个已知错误。

如果你需要保存实例，并添加一些东西到你的outState Bundle，你可以使用以下方法:

@Override
protected void onSaveInstanceState(Bundle outState) {
    outState.putString("WORKAROUND_FOR_BUG_19917_KEY", "WORKAROUND_FOR_BUG_19917_VALUE");
    super.onSaveInstanceState(outState);
}

EDIT2:如果您试图在Activity在后台消失后执行事务，也可能会发生这种情况。为了避免这种情况，你应该使用commitAllowingStateLoss()

EDIT3: The above solutions were fixing issues in the early support.v4 libraries from what I can remember. But if you still have issues with this you MUST also read @AlexLockwood 's blog : Fragment Transactions & Activity State Loss Summary from the blog post (but I strongly recommend you to read it) : NEVER commit() transactions after onPause() on pre-Honeycomb, and onStop() on post-Honeycomb Be careful when committing transactions inside Activity lifecycle methods. Use onCreate(), onResumeFragments() and onPostResume() Avoid performing transactions inside asynchronous callback methods Use commitAllowingStateLoss() only as a last resort

你可以使用FragmentActivity。onStart在popBackStackImmediate之前

是这样的:

public void backStackFragment() {
    this.start();
    getFragmentManager().popBackStackImmediate();
}

public void start(){
    FragmentActivity a = getActivity();
    if(a instanceof DepositPlanPadActivity){
      ((DepositPlanPadActivity)a).onStart();
    }
    if(a instanceof SmallChangePlanPad){
            ((SmallChangePlanPad)a).onStart();
        }
        if(a instanceof UserCenterActivity){
            ((UserCenterActivity)a).onStart();
        }
    }

http://jorryliu.blogspot.com/2014/09/illegalstateexception-can-not-perform.html

经过研究，这个问题的解决方案是做你的片段提交在onresume。

来源:https://wenchaojames.wordpress.com/2013/01/12/illegalstateexception-from-onactivityresult/