FragmentManager.getFragment() NullPointerException

Question

我使用的是支持库v4，无法保存片段的状态。

@Override
protected void onSaveInstanceState(Bundle outState)
{
    ...
    if(mFragment != null)
        getSupportFragmentManager().putFragment(outState, "frag", mFragment);
    ...
}
@Override
protected void onCreate(Bundle savedInstanceState)
{
    ...
    if(savedInstanceState != null)
    {
        //Here I get NullPointerException
        getSupportFragmentManager().getFragment(savedInstanceState, "frag");
    }
    ...
}

当我调用getFragment()时，会抛出NullPointerException (savedInstanceState包含带有“frag”的条目)。

下面是logcat输出的部分：

04-18 00:10:56.719: E/AndroidRuntime(14644): Caused by: java.lang.NullPointerException
04-18 00:10:56.719: E/AndroidRuntime(14644):    at android.support.v4.app.FragmentManagerImpl.getFragment(FragmentManager.java:569)

此外，我还尝试调用getFragments()，它返回null。我觉得很奇怪。

我会感谢你的帮助！

解决方案：

我忘了在onCreate方法中使用onCreate。

Answer 1

感谢@Fllo。问题是我忘记调用父活动的onSaveInstanceState()。

@Override
protected void onSaveInstanceState(Bundle outState)
{
    //Added this and the problem was solved
    super.onSaveInstanceState(outState);
    ...
}