如何使用前一个 Fragment 的 EditText 的输入来更改 Fragment 中的 TextView？

Question

我已经实现了另一个教程中的代码，但我不知道如何使用此代码更改 TextView。我知道我必须使用 ViewModel 的 setAnswer 但我不知道在哪里使用它。我对编程比较陌生，因此非常感谢您的帮助！在第一个问题之后，还有另外 2 个问题，每个问题都有一个 EditText，输入的内容也应该显示在问题的下一个片段中。

这是我的 ViewModel：

public class SharedViewModel extends ViewModel {


public HashMap<Integer, MutableLiveData<String>> answers = new HashMap<Integer, MutableLiveData<String>>(){{
    put(1, new MutableLiveData<String>());
    put(2, new MutableLiveData<String>());
    put(3, new MutableLiveData<String>());
}};



public MutableLiveData<String> getAnswer(int questionId) {
    return answers.get(questionId);
}

public void setAnswer(int questionId, String answer) {
    if (answers.get(questionId) != null) {
        answers.get(questionId).setValue(answer);
    }
}
}

这是我的带有 EditText 的片段：

public class FragmentQuestion1 extends Fragment {

private Button btnNavFrag1;
private EditText mEditTextQuestion1;
private SharedViewModel viewModel;

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_question_1, container, false);

    btnNavFrag1 = view.findViewById(R.id.btn_question1);

    mEditTextQuestion1 = view.findViewById(R.id.edit_text_question_1);

    mEditTextQuestion1.addTextChangedListener(new NumberTextWatcher(mEditTextQuestion1));

    m_bar = view.findViewById(R.id.progress_bar_question_1);


    btnNavFrag1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            viewModel.getAnswer(1);

            ((GameActivity)getActivity()).setViewPager(2);

        }
    });

    return view;
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    viewModel = ViewModelProviders.of(getActivity()).get(SharedViewModel.class);
    viewModel.getAnswer(1).observe(this, new Observer<String>() {
        @Override
        public void onChanged(@Nullable String answer) {
            tv_answer1.setText(answer);
        }
    });
}

这是我的第二个片段，前一个 EditText 的输入应该显示在 TextView 中：

public class FragmentAnswer1 extends Fragment {

private View btnNavFragAns1;
private TextView tv_answer1;
private SharedViewModel viewModel;

@Nullable
@Override
public View onCreateView( LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_question_answer_1, container, false);

    btnNavFragAns1 = view.findViewById(R.id.next_question_1);

    tv_answer1 = view.findViewById(R.id.answer_player_1_text_view);

    btnNavFragAns1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            ((GameActivity)getActivity()).setViewPager(3);

        }
    });

    return view;
}

@Override
public void onActivityCreated(Bundle bundle) {
    super.onActivityCreated(bundle);

    viewModel = ViewModelProviders.of(getActivity()).get(SharedViewModel.class);
    viewModel.getAnswer(1).observe(this, new Observer<String>() {
        @Override
        public void onChanged(@Nullable String answer) {
            tv_answer1.setText(answer);
        }
    });
}
}

Answer 1

1. Create a global variable(String) 存储您的 EdiText 的文本

2. 当您使用EditText 打开Fragment 时，您可以使用Button (onClickListener) 或onDetached 来设置您的全局变量。

   ((MyApplication) this.getApplication()).setSomeVariable(edittext.getText().toString());

3. 当您使用TextView 返回您的Fragment 时，您将其添加到void onStart()

   textview.setText(((MyApplication) this.getApplication()).getSomeVariable());