造成java.IllegalStateException错误，无活动，导航到片段的第二次，只有当 [英] causing a java.IllegalStateException error, No Activity, only when navigating to Fragment for the SECOND time

问题描述

我得到一个十分不解的错误，我不知道如何甚至开始学习的。

I am getting a very puzzling bug that I have no idea how to even begin working through.

我有一个活动一个简单的应用程序，该意见与片段实施。其中一个片段有它内部的ViewPager;所以我决定，我想用getChildFragmentManager类V4支持库。我还不得不使用ActionBarSherlock，这引起一个问题，因为它不与v4的库的v11的出货。

I have a simple app with one activity, the views are implemented with Fragments. One of the fragments has a ViewPager inside of it; so I decided I that I wanted to use the getChildFragmentManager class of the v4 support library. I also had to use ActionBarSherlock, which caused a problem, because it does not ship with the v11 of the v4 library.

我解决了这个问题通过与V11库替换V4支持库在ABS，一切编译，似乎是工作，包括ViewPager。

I fixed this by replacing the v4 support library in ABS with the v11 library, and everything compiled and appeared to be working, including the ViewPager.

下面是奇怪的一部分：

第一次与ViewPager片段打开，它工作正常;但第二次，导航到，应用程序崩溃，给人一种无用的堆栈跟踪。从调试，我发现这个问题是由getChildFragmentManager返回的FragmentManager;它抛出的无活动错误。

The first time the fragment with the ViewPager opens, it works properly; but the SECOND time it is navigated to, the app crashes, giving a useless stack trace. From debugging, I discovered that the problem was with the FragmentManager returned by getChildFragmentManager; it throws the No Activity error.

没有任何人有任何想法可能会造成什么呢？

Does anybody have any idea what could be causing this?

我会后code，你认为是相关的。

I will post code that you think is relevant.

感谢您， 大卫

推荐答案

我跟着 jeremyvillalobos链接回答（其中是非常有益的），导致我这种解决方法。

I followed the link in jeremyvillalobos answer (which was very helpful) that led me to this workaround.

public class CustomFragment extends Fragment {
    private static final Field sChildFragmentManagerField;

    static {
        Field f = null;
        try {
            f = Fragment.class.getDeclaredField("mChildFragmentManager");
            f.setAccessible(true);
        } catch (NoSuchFieldException e) {
            Log.e(LOGTAG, "Error getting mChildFragmentManager field", e);
        }
        sChildFragmentManagerField = f;
    }

    @Override
    public void onDetach() {
        super.onDetach();

        if (sChildFragmentManagerField != null) {
            try {
                sChildFragmentManagerField.set(this, null);
            } catch (Exception e) {
                Log.e(LOGTAG, "Error setting mChildFragmentManager field", e);
            }
        }
    }

    ...
}

它为我好，而不需要重新实例片段。

It works for me well, without the need to reinstantiate the fragment.

这篇关于造成java.IllegalStateException错误，无活动，导航到片段的第二次，只有当的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！