如何在多个 EditText 中键入数据后使用 ViewModel 更新 TextView？

Question

我有 3 个问题，每个问题都显示在一个片段中。在每个问题之后，都有一个包含 TextView 的片段，其中包含在前一个问题片段的 EditText 中输入的答案。我设法实现了第一个问题的输入数据显示在第二个片段中，但是当我转到下一个问题时，在 EditText 中有第一个问题的数据。我如何使用此处显示的代码，以便每个问题的输入仅显示在下一个片段中？ (片段：问题1 --> 答案1 --> 问题2 --> 答案2 --> 问题3 --> 答案3)

这是前两个片段和模型视图的代码：

第一个问题片段：

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);

    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) {
            viewModel.setAnswer(1, answer);
            mEditTextQuestion1.setText(answer);
        }
    });
}

第一个答案概述片段：

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) {
            viewModel.setAnswer(1, answer);
            tv_answer1.setText(answer);
        }
    });
}

共享视图模型：

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);
    }
}
}

Answer 1

您只需要一个共享 ViewModel，它存储 LiveData 个答案列表，也许还有一个问题列表。

这是您 SharedViewModel 的更新版本：

public class ContestViewModel extends ViewModel {

private HashMap<Int,LiveData<String>> answers = new HashMap<>();

public LiveData<String> getAnswer(int questionId) {
    return answers.get(questionId);
}
public void setAnswer(int questionId, String answer) {
    // TODO make sure that answers.get is not null
    answers.get(questionId).setValue(answer);
  }
}

现在，在每个片段中调用 viewModel.getAnswer(id)。因此，他们每个人都有一个单独的实时数据 question/answer。

如何在多个 EditText 中键入数据后使用 ViewModel 更新 TextView？

How to use ViewModel to update TextView after typing data in several EditTexts?

android

android-fragments

android-viewmodel

android-jetpack