片段savedInstanceState不起作用

Question

I have several fragments here and there's this one fragment where I want to save its state when I get back to it. I tried doing it in a testfragment where, when I click the button, the textview text will change to "test1"(The default text of the textview is "New Text"). So the textview changes the text, but when I move into another fragment and get back to it ( HomeFragment ), the textview is going to its default state text ("New Text"). So I think the savedInstanceState is not working because if it does, it should have "test1" when I get back to the fragment. Here's my code:

public class HomeFragment extends Fragment {
    public Button button;
    public TextView txt_test;
    public String data_test;
    public HomeFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_home, container, false);

        return view;
    }

    public void onActivityCreated(Bundle savedInstanceState){
        super.onActivityCreated(savedInstanceState);
        if(savedInstanceState == null){

        }
        else{
            data_test = savedInstanceState.getString("txt_test");
            txt_test = (TextView) getActivity().findViewById(R.id.textView2);
            txt_test.setText(data_test);
        }
        button = (Button) getActivity().findViewById(R.id.button3);
        txt_test = (TextView) getActivity().findViewById(R.id.textView2);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                txt_test.setText("test1");

            }
        });
    }

    public void onSaveInstanceState(Bundle savedInstanceState){
        super.onSaveInstanceState(savedInstanceState);
        savedInstanceState.putString("txt_test",data_test);
    }

}

Answer 1

public class HomeFragment extends Fragment {
    Button button;
    TextView txt_test;
    String data_test;

    public HomeFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_home, container, false);
        txt_test = (TextView) view.findViewById(R.id.textView2);
        button = (Button) view.findViewById(R.id.button3);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                txt_test.setText("test1");
            }
        });

        if(savedInstanceState == null) {
            // do nothing
        } else {
            data_test = savedInstanceState.getString("txt_test");
            txt_test.setText(data_test);
        }
        return view;
    }

    @Override
    public void onSaveInstanceState(Bundle savedInstanceState){
        super.onSaveInstanceState(savedInstanceState);
        savedInstanceState.putString("txt_test",data_test);
    }
}