房间持久性库(依赖性问题)，MVVM设计模式 [英] Room persistence library (dependency issue), MVVM design pattern

问题描述

遵循MVVM教程，并添加房间依赖性

1-我在编译时遇到此错误:

Note: Failed to read get kotlin metadata for [Ljava.lang.Object;@54d771f9

Note: Failed to read get kotlin metadata for [Ljava.lang.Object;@4c00a268

Note: Failed to read get kotlin metadata for [Ljava.lang.Object;@42104314

Note: Failed to read get kotlin metadata for [Ljava.lang.Object;@203b72ad

2-也是这样:(已解决)

error: cannot find symbol class of

在MainActivity中添加此代码时:

public class MainActivity extends AppCompatActivity {
private NoteViewModel noteViewModel;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //error is here in the ViewModelProviders.of
    noteViewModel = new ViewModelProviders.of(this).get(NoteViewModel.class);
    noteViewModel.getAllNotes().observe(this, notes -> {
        //update RecyclerView
        Toast.makeText(MainActivity.this, "onChanged", Toast.LENGTH_SHORT).show();
    });
 }
}

• build.gradle(项目):

  repositories {
   google()
   jcenter()
   maven { url "https://kotlin.bintray.com/kotlinx/" }
  }
  
  
  
  allprojects {
   repositories {
    google()
   jcenter()
   maven { url "https://kotlin.bintray.com/kotlinx/" }
   }
  }
  

• build.gradle(app):

  room_version = "2.1.0-alpha06"
  
  implementation "androidx.room:room-runtime:$room_version"
  annotationProcessor "androidx.room:room-compiler:$room_version"
  

解决方案

删除new， 这将起作用:

noteViewModel = ViewModelProviders.of(this).get(NoteViewModel.class);

Iam following MVVM tutorial and when adding Room dependency

1- I got this this error in compile:

Note: Failed to read get kotlin metadata for [Ljava.lang.Object;@54d771f9

Note: Failed to read get kotlin metadata for [Ljava.lang.Object;@4c00a268

Note: Failed to read get kotlin metadata for [Ljava.lang.Object;@42104314

Note: Failed to read get kotlin metadata for [Ljava.lang.Object;@203b72ad

2- also this: (SOLVED)

error: cannot find symbol class of

when adding this code in MainActivity:

public class MainActivity extends AppCompatActivity {
private NoteViewModel noteViewModel;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //error is here in the ViewModelProviders.of
    noteViewModel = new ViewModelProviders.of(this).get(NoteViewModel.class);
    noteViewModel.getAllNotes().observe(this, notes -> {
        //update RecyclerView
        Toast.makeText(MainActivity.this, "onChanged", Toast.LENGTH_SHORT).show();
    });
 }
}

• build.gradle(project):

  repositories {
   google()
   jcenter()
   maven { url "https://kotlin.bintray.com/kotlinx/" }
  }
  
  
  
  allprojects {
   repositories {
    google()
   jcenter()
   maven { url "https://kotlin.bintray.com/kotlinx/" }
   }
  }
  

• build.gradle(app):

  room_version = "2.1.0-alpha06"
  
  implementation "androidx.room:room-runtime:$room_version"
  annotationProcessor "androidx.room:room-compiler:$room_version"
  

解决方案

remove new, this will work:

noteViewModel = ViewModelProviders.of(this).get(NoteViewModel.class);

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