AndroidStudio 3.2.1生成的ViewDataBindingclass分包中包含视图布局数据变量类型时报错

Question

我的视图模型包含在 "ViewModels" 包中。在我的片段布局 xml 文件中将其中之一设置为数据变量类型时，生成的 ViewDataBinding class 会尝试将包作为文件导入。例如：

import com.xyz.myapp.ViewModels;

而不是：

import com.xyz.myapp.ViewModels.*;

然后它继续将视图模型引用为 ViewModels.MyFragmentViewModel 导致进一步的错误。我发现一个解决方法是将我所有的视图模型文件放在我的 com.xyz.myapp 目录中。这样做时一切正常。

这与询问的相同我没有足够的声誉来发表评论。我错过了什么吗？我需要设置一些选项吗？或者这只是一个错误？

TestFragment.java

public class TestFragment extends Fragment {
    @Inject
    MyViewModelFactory viewModelFactory;

    private MyFragmentViewModel vm;

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

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        vm = ViewModelProviders.of(this, viewModelFactory).get(MyFragmentViewModel.class);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        FragmentTestBinding binding = DataBindingUtil.inflate(inflater, R.layout.fragment_test, container, false);
        View view = binding.getRoot();
        binding.setVm(vm);
        return view;
    }

    @Override
    public void onAttach(Context context) {
        AndroidSupportInjection.inject(this);
        super.onAttach(context);
    }

    @Override
    public void onDetach() {
        super.onDetach();
    }
}

fragment_test.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable
            name="vm"
            type="com.xyz.myapp.ViewModels.MyFragmentViewModel"/>
    </data>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">


        <EditText
            android:id="@+id/editText"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:ems="10"
            android:inputType="textPersonName"
            android:text="@{vm.TEMP}" />
    </LinearLayout>
</layout>

MyFragmentViewModel.java

public class MyFragmentViewModel extends ViewModel {
    public MyFragmentViewModel (){}
    public String TEMP = "TEST STRING";
}

FragmentTestBinding.java

这是生成的class。错误行有注释。 4个错误

import com.xyz.myapp.ViewModels; //Error

public abstract class FragmentTestBinding extends ViewDataBinding {
  @NonNull
  public final CheckBox checkBox;

  @NonNull
  public final EditText editText;

  @Bindable
  protected ViewModels.ProfileViewModel mVm; //Error

  protected FragmentTestBinding(DataBindingComponent _bindingComponent, View _root,
      int _localFieldCount, CheckBox checkBox, EditText editText) {
    super(_bindingComponent, _root, _localFieldCount);
    this.checkBox = checkBox;
    this.editText = editText;
  }

  public abstract void setVm(@Nullable ViewModels.ProfileViewModel vm); //Error

  @Nullable
  public ViewModels.ProfileViewModel getVm() { //Error
    return mVm;
  }

  @NonNull
  public static FragmentTestBinding inflate(@NonNull LayoutInflater inflater,
      @Nullable ViewGroup root, boolean attachToRoot) {
    return inflate(inflater, root, attachToRoot, DataBindingUtil.getDefaultComponent());
  }

  @NonNull
  public static FragmentTestBinding inflate(@NonNull LayoutInflater inflater,
      @Nullable ViewGroup root, boolean attachToRoot, @Nullable DataBindingComponent component) {
    return DataBindingUtil.<FragmentTestBinding>inflate(inflater, com.camapps.linkshare.R.layout.fragment_test, root, attachToRoot, component);
  }

  @NonNull
  public static FragmentTestBinding inflate(@NonNull LayoutInflater inflater) {
    return inflate(inflater, DataBindingUtil.getDefaultComponent());
  }

  @NonNull
  public static FragmentTestBinding inflate(@NonNull LayoutInflater inflater,
      @Nullable DataBindingComponent component) {
    return DataBindingUtil.<FragmentTestBinding>inflate(inflater, com.camapps.linkshare.R.layout.fragment_test, null, false, component);
  }

  public static FragmentTestBinding bind(@NonNull View view) {
    return bind(view, DataBindingUtil.getDefaultComponent());
  }

  public static FragmentTestBinding bind(@NonNull View view,
      @Nullable DataBindingComponent component) {
    return (FragmentTestBinding)bind(component, view, com.camapps.linkshare.R.layout.fragment_test);
  }
}

编译器输出

Java compiler: (4 errors)
C:/Users/user/AndroidStudioProjects/myapp   
    app/build/generated/data_binding_base_class_source_out/debug/dataBindingGenBaseClassesDebug/out 
        com/xyz/myapp/databinding/FragmentTestBinding.java  
            error: cannot find symbol class ViewModels  
            error: package ViewModels does not exist    
            error: package ViewModels does not exist    
            error: package ViewModels does not exist

Answer 1

这是一个有趣的问题，表明需要遵循约定。如Android - Package Name convention、

所述

Android follows normal java package conventions

和 Oracle suggests 那

Package names are written in all lower case to avoid conflict with the names of classes or interfaces.

现在 Android 数据绑定库 或另一个依赖库试图创建干净的代码并认为 class 名称是 ViewModels.ProfileViewModel , 遵循并期待一般的 Java 命名约定。

要解决您的问题，请开始遵循给定的约定并将您的包重命名为 viewmodels。

AndroidStudio 3.2.1生成的ViewDataBindingclass分包中包含视图布局数据变量类型时报错

Generated ViewDataBinding class in Android Studio 3.2.1 has an error when view layout data variable type is contained in a subpackage

android

android-databinding

android-viewmodel

TestFragment.java

fragment_test.xml

MyFragmentViewModel.java

FragmentTestBinding.java

编译器输出