Android 删除行onclick时出现房间数据库错误

我已将SQLite数据库定义为：

@Database(entities = {PlaceSaved.class},version = 1)
public abstract class PlaceDatabase extends RoomDatabase {

    public abstract DatabaseInterface databaseInterface();

    @Override
    protected SupportSQLiteOpenHelper createOpenHelper(DatabaseConfiguration config) {
        return null;
    }

    @Override
    protected InvalidationTracker createInvalidationTracker() {
        return null;
    }

}

定义见：

@Entity
public class PlaceSaved {

  @PrimaryKey(autoGenerate = true)
  private int id;

  @ColumnInfo(name = "time")
  private String time;

  @ColumnInfo(name="title")
  private String title;

  public PlaceSaved(){

  }

  public PlaceSaved(String time, String title) {
    this.time = time;
    this.title = title;
  }

  public String getTime() {
    return time;
  }

  public void setTime(String time) {
    this.time = time;
  }

  public String getTitle() {
    return title;
  }

  public void setTitle(String title) {
    this.title = title;
  }

  public int getId() {
    return id;
  }

  public void setId(int id) {
    this.id = id;
  }
}

相应的DAO是：

@Dao
public interface DatabaseInterface {
  @Query("SELECT * FROM placesaved")
  List<PlaceSaved> getAllItems();

  @Insert
  void insertAll(PlaceSaved... todoListItems);
  @Delete
  public void delete(PlaceSaved... todoListItems);
  @Update
  public void update(PlaceSaved...todoListItems);
}

recyclerview的名称为：（**注意：onCreate在末尾更新并发布）

它仍然给出语法错误：

Error:(71, 17) error: cannot find symbol method delete(PlaceSaved)

和2个警告（不是因为维舒的回答，它以前就存在过）：

错误：更新：
添加

db.databaseInterface（）.delete（infoItem）
在removeitem中给出：

java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long period of time.
      at android.arch.persistence.room.RoomDatabase.assertNotMainThread(RoomDatabase.java:164)                                                                             
     at android.arch.persistence.room.RoomDatabase.beginTransaction(RoomDatabase.java:211)
     at DatabaseInterface_Impl.delete(DatabaseInterface_Impl.java:94)
     at PlacesAdapter.removeItem(PlacesAdapter.java:69)
     at PlacesAdapter.access$000(PlacesAdapter.java:20)
     at PlacesAdapter$1.onClick(PlacesAdapter.java:45)
     at android.view.View.performClick(View.java:6294)

为什么要在
removitem（）中传递
PlaceSaved
的
ArrayList
removietem（）
仅接受
PlaceSaved

因此，将您的
onclick
更改为

removeItem(items.get(holder.getAdapterPosition()));

在方法签名中将
holder
final-in-method-signature
final-PlacesAdapter.ViewHolder-holder
设置为final，否则它将无法编译

您已经在
PlaceDatabase
中定义了
delete
，并且正在调用
PlaceSaved
，这就是您得到
错误的原因：（68,17）错误：找不到符号方法delete（PlaceSaved）

您可以在
PlacesAdapter
中传递
db
，就像
items
like
PlacesAdapter（items，db）

改变

adapter = new PlacesAdapter(items);

到

现在，您的PlacesAdapter将具有
db
实例。您可以回复
placeSaved.delete（infoItem）带有
db.delete（infoItem）

改变

List<PlaceSaved> items;
public PlacesAdapter(List<PlaceSaved> items) {
    this.items = items;
}

到

嗨，维苏，谢谢你的评论。但我还是不知道如何传递数据库。我已经更改了OnClick，它现在是有效的，但是removeItem方法仍然给出错误：错误：（69，17）错误：找不到符号方法delete（PlaceSaved）错误：任务执行失败：app:compiledBugJavaWithJavaC'>编译失败；有关详细信息，请参阅编译器错误输出。更新的答案！！维舒，再次感谢您的回复。更改PlacesAdapter（items，db）给出了错误：错误：（44,19）错误：类PlacesAdapter中的构造函数PlacesAdapter不能应用于给定的类型；必需：列表已找到：列表，位置数据库原因：实际参数列表和形式参数列表的长度不同更改构造函数，如answerHi中所述，这是非常重要的。现在，我的removietem看起来像：
private void removietem（PlaceSaved infoItem）{db.delete（infoItem）；Log.v（TAG，“remove Item called”）；}
没有错误，但也没有删除该项。
@Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.places_layout);

    final PlaceDatabase db = Room.databaseBuilder(getApplicationContext(), PlaceDatabase.class, "production")
        .build();

    Runnable r = new Runnable() {
      @Override
      public void run() {
        items = db.databaseInterface().getAllItems();
        recyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
        recyclerView.setLayoutManager(new LinearLayoutManager(getApplication()));
        adapter = new PlacesAdapter(items, db);
        adapter.notifyDataSetChanged();
        recyclerView.setAdapter(adapter);
      }
    };

Error:(71, 17) error: cannot find symbol method delete(PlaceSaved)

PlaceSaved.java
Warning:(11, 8) There are multiple good constructors and Room will pick the no-arg constructor. You can use the @Ignore annotation to eliminate unwanted constructors.

PlaceDatabase.java
Warning:(13, 17) Schema export directory is not provided to the annotation processor so we cannot export the schema. You can either provide `room.schemaLocation` annotation processor argument OR set exportSchema to false.

java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long period of time.
      at android.arch.persistence.room.RoomDatabase.assertNotMainThread(RoomDatabase.java:164)                                                                             
     at android.arch.persistence.room.RoomDatabase.beginTransaction(RoomDatabase.java:211)
     at DatabaseInterface_Impl.delete(DatabaseInterface_Impl.java:94)
     at PlacesAdapter.removeItem(PlacesAdapter.java:69)
     at PlacesAdapter.access$000(PlacesAdapter.java:20)
     at PlacesAdapter$1.onClick(PlacesAdapter.java:45)
     at android.view.View.performClick(View.java:6294)

removeItem(items.get(holder.getAdapterPosition()));

adapter = new PlacesAdapter(items);

adapter = new PlacesAdapter(items, db);

List<PlaceSaved> items;
public PlacesAdapter(List<PlaceSaved> items) {
    this.items = items;
}

List<PlaceSaved> items;
PlaceDatabase db;
public PlacesAdapter(List<PlaceSaved> items, PlaceDatabase db) {
    this.items = items;
    this.db = db
}

 placeSaved.delete(infoItem);

db.databaseInterface().delete(infoItem);