FragmentActivity：不能投从片段派生类 [英] FragmentActivity: Cannot cast from Fragment to derived class

问题描述

我试图用一个片段在FragmentActivity像这样：

I am trying to use a Fragment in a FragmentActivity like so:

TutViewerFragment viewer = (TutViewerFragment)    
getSupportFragmentManager().findFragmentById(R.id.tutview_fragment);

和我的 TutViewerFragment 扩展片段。但是我得到一个错误：

And my TutViewerFragment extends Fragment. However I am getting an error:

不能从片段转换为TutViewerFragment。

Cannot cast from Fragment to TutViewerFragment.

我真的不明白为什么会这样。为什么不能定投？

I really don't understand why this is happening. Why can't it be cast?

推荐答案

正在扩展错误的片段类。导入 android.support.v4.app.Fragment 而不是 android.app.Fragment 。

You are extending the wrong Fragment class. Import android.support.v4.app.Fragment instead of android.app.Fragment.

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