从ViewModel调用的Android DataBinding方法未与片段中的onClick一起执行

Question

我想用ViewModel从我的onClick()类中调用一个方法，但是调用只是没有执行。否则，DataBinding可以正常工作。

android:onClick="@{() -> ViewModel.test()}"

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/androidxmlns:bind="http://schemas.android.com/apk/res-auto"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <variable
            name="Project"
            type="de.umr.studipro3000.model.Project" />

        <variable
            name="ViewModel"
            type="de.umr.studipro3000.viewmodel.ProjectOverviewViewModel" />
    </data>



        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:clickable="true"
            android:focusable="true"
            android:background="?attr/selectableItemBackground"
            android:onClick="@{() -> ViewModel.test()}"
            android:padding="8dp">

            <TextView
                android:id="@+id/text_view_projectName"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@{Project.name}"
                android:textAppearance="@style/TextAppearance.AppCompat.Large" />
        </RelativeLayout>


</layout>

奇怪的是，这执行得很好。

android:onClick="@{() -> System.out.println(Project.name)}"

<data>

    <variable
        name="Project"
        type="de.umr.studipro3000.model.Project" />

    <variable
        name="ViewModel"
        type="de.umr.studipro3000.viewmodel.ProjectOverviewViewModel" />
</data>



    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:clickable="true"
        android:focusable="true"
        android:background="?attr/selectableItemBackground"
        android:onClick="@{() -> System.out.println(Project.name)}"
        android:padding="8dp">

        <TextView
            android:id="@+id/text_view_projectName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{Project.name}"
            android:textAppearance="@style/TextAppearance.AppCompat.Large" />
    </RelativeLayout>

这是ViewModel：

public class ProjectOverviewViewModel extends ViewModel {
  private Repository repository;
  private AuthService authService;

  private MutableLiveData<List<Project>> projectsLiveData;

  private String errorMessage;

  private ProjectOverViewNavigator navigator;

  public void setNavigator(ProjectOverViewNavigator navigator) {
    this.navigator = navigator;
  }

  public ProjectOverviewViewModel() {
    this.repository = Repository.getInstance();
    this.authService = AuthService.getInstance();
    this.errorMessage = "";
    projectsLiveData = new MutableLiveData<>();
    handleResponse(repository.projects((authService.currentToken.getValue())));
  }

  private void handleResponse(LiveData<ProjectListResponse> projectListResponseLiveData) {
    projectListResponseLiveData.observeForever(
        projectListResponse -> {
          ProjectListSuccessResponse projectListSuccessResponse =
              projectListResponse.getProjectListSuccessResponse();

          if (projectListSuccessResponse != null) {
            projectsLiveData.setValue(projectListSuccessResponse.getResult());
            System.out.println(projectsLiveData.getValue().toString());
          } else {
            errorMessage = projectListResponse.getErrorResponse().getError();
          }
        });
  }

  public void itemClick(Project project) {
    System.out.println("CLICKED");
    navigator.onItemClick(project);
  }

  public void test(){
    System.out.println("TEST");
  }

  public MutableLiveData<List<Project>> getProjectsLiveData() {
    return projectsLiveData;
  }

  public void setProjectsLiveData(MutableLiveData<List<Project>> projectsLiveData) {
    this.projectsLiveData = projectsLiveData;
  }

  public String getErrorMessage() {
    return errorMessage;
  }

  public void setErrorMessage(String errorMessage) {
    this.errorMessage = errorMessage;
  }
}

这是我的片段

public class projectOverviewFragment extends Fragment implements ProjectOverViewNavigator {

  private ProjectOverviewViewModel viewModel;
  private ProjectAdapter adapter;
  private FragmentProjectOverviewBinding binding;
  private NavController navController;

  @Override
  public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    viewModel = new ViewModelProvider(this).get(ProjectOverviewViewModel.class);
    viewModel.setNavigator(this);
    adapter = new ProjectAdapter();
  }

  @Nullable
  @Override
  public View onCreateView(
      @NonNull LayoutInflater inflater,
      @Nullable ViewGroup container,
      @Nullable Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);
    binding = FragmentProjectOverviewBinding.inflate(inflater, container, false);
    binding.setProjectOverviewViewModel(viewModel);
    binding.setLifecycleOwner(this);


    RecyclerView recyclerView = binding.recyclerViewProjects;
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
    recyclerView.setAdapter(adapter);

    binding.getProjectOverviewViewModel().test();

    return binding.getRoot();
  }

  @Override
  public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    navController = Navigation.findNavController(view);

    viewModel
        .getProjectsLiveData()
        .observe(getViewLifecycleOwner(), projects -> adapter.setProjects(projects));
  }

  public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
    super.onCreateContextMenu(menu, v, menuInfo);
    MenuInflater inflater = getActivity().getMenuInflater();
    inflater.inflate(R.menu.setting_menu, menu);
  }

  @Override
  public boolean onContextItemSelected(MenuItem item) {
    /*case R.id.first_action:
        // your first action code
        return true;
    case R.id.second_action:
        // your second action code
     */
    return true;
  }


  @Override
  public void onItemClick(Project project) {
    System.out.println(project.getDescription());

  /*  projectOverviewFragmentDirections.ActionProjectOverviewFragmentToProjectDetailsFragment action =
        projectOverviewFragmentDirections.actionProjectOverviewFragmentToProjectDetailsFragment(
            project.getId());

    navController.navigate(action);*/
  }
}

Answer 1

我必须为Project Adapter中的单个Listitem执行Viewmodel的数据绑定。 ProjectAdapter的VieModel在片段中设置。

public class ProjectAdapter extends RecyclerView.Adapter<ProjectAdapter.ProjectViewHolder> {
  private ProjectOverviewViewModel viewModel;

  public void setProjects(List<Project> projects) {
    this.projects = projects;
    notifyDataSetChanged();
  }

  public void setViewModel(ProjectOverviewViewModel viewModel) {
    this.viewModel = viewModel;
  }

  public static class ProjectViewHolder extends RecyclerView.ViewHolder {
    private ProjectItemBinding projectItemBinding;

    public ProjectViewHolder(@NonNull ProjectItemBinding projectItemBinding) {
      super(projectItemBinding.getRoot());
      this.projectItemBinding = projectItemBinding;
    }
  }

  private List<Project> projects = new ArrayList<>();

  @NonNull
  @Override
  public ProjectViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    ProjectItemBinding projectItemBinding =
        DataBindingUtil.inflate(
            LayoutInflater.from(parent.getContext()), R.layout.project_item, parent, false);

    return new ProjectViewHolder(projectItemBinding);
  }

  @Override
  public void onBindViewHolder(@NonNull ProjectViewHolder holder, int position) {
    Project currentProject = projects.get(position);
    holder.projectItemBinding.setProject(currentProject);
    holder.projectItemBinding.setProjectOverviewViewModel(viewModel);
  }

  @Override
  public int getItemCount() {
    return projects.size();
  }
}

public View onCreateView(
      @NonNull LayoutInflater inflater,
      @Nullable ViewGroup container,
      @Nullable Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);
    binding = FragmentProjectOverviewBinding.inflate(inflater, container, false);
    binding.setLifecycleOwner(this);
    binding.setProjectOverviewViewModel(viewModel);

    RecyclerView recyclerView = binding.recyclerViewProjects;
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
    recyclerView.setHasFixedSize(true);
    adapter.setViewModel(viewModel);
    recyclerView.setAdapter(adapter);

    return binding.getRoot();
  }