onCreate()中findViewByid无法获取activity_main.xml中R.id.view

myTextview,myButton是在fragment_main.xml中的，在没引进fragment_main.xml之前，你是通过findViewById找不到的。。,所以要在onCreateView中引入。

public static class PlaceholderFragment extends Fragment {

public PlaceholderFragment() {

}

@Override

public View onCreateView(LayoutInflater inflater, ViewGroup container,

Bundle savedInstanceState) {

View rootView = inflater.inflate(R.layout.fragment_main, container,

false);

TextView textview = (TextView)rootView.findViewById(R.id.view);

System.out.println(textview);

testview.setText("Hello Android!");

return rootView;

}

}
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