@Entity public class User { @PrimaryKey(autoGenerate = true) public int id; @ColumnInfo(name = "picture_edit") public String PictureEdit; @ColumnInfo(name = "picture_title") public String PictureTitle; //若设为private,要添加set、get接口 @ColumnInfo(name = "picture_path") public String PicturePath; }中val报错

这段代码是 Java 语言的实体类定义，而 `val` 是 Kotlin 语言中的关键字，所以在 Java 中不能使用 `val` 关键字。Java 中声明变量需要使用 `type variableName` 的形式，例如：

public class User {
    @PrimaryKey(autoGenerate = true)
    public int id;
    @ColumnInfo(name = "picture_edit")
    public String pictureEdit;
    @ColumnInfo(name = "picture_title")
    public String pictureTitle;
    @ColumnInfo(name = "picture_path")
    public String picturePath;
}

注意变量名应该使用小驼峰命名法，即第一个单词的首字母小写，后面的单词首字母大写。另外，变量的作用域也应该根据实际情况进行调整，不一定要全部设为 `public`。

相关问题

@Entity(tableName = "post_entity") data class PostEntity( var path :String, var content:String, var time:Long, var likeCount:Int, @PrimaryKey(autoGenerate = true) var id: Int = 0 ) @Dao interface PostDao { @Insert(onConflict = OnConflictStrategy.REPLACE) suspend fun insertPost(post: PostEntity) @Query("SELECT * FROM post_entity") suspend fun getAll(): List<PostEntity> } 编译报错 The query returns some columns [path, content, time, likeCount, id] which are not used by java.lang.Object. You can use @ColumnInfo annotation on the fields to specify the mapping. You can annotate the method with @RewriteQueriesToDropUnusedColumns to direct Room to rewrite your query to avoid fetching unused columns. You can suppress this warning by annotating the method with @SuppressWarnings(RoomWarnings.CURSOR_MISMATCH). Columns returned by the query: path, content, time, likeCount, id. Fields in java.lang.Object: . public abstract java.lang.Object getAll(@org.jetbrains.annotations.NotNull ^ 帮我改正

这个错误是由于你的查询返回的字段与实体类中定义的字段不一致所导致的。为了解决这个错误，你需要在实体类中使用 @ColumnInfo 注解来显式指定每个字段的映射关系，指定与查询返回的字段相同的名称。另外，你可以在 DAO 接口的方法上添加 @SuppressWarnings(RoomWarnings.CURSOR_MISMATCH) 注解来抑制警告。此外，还可以使用 @RewriteQueriesToDropUnusedColumns 注解来让 Room 重写查询以避免获取未使用的列。以下是修改后的代码：

@Entity(tableName = "post_entity")
data class PostEntity(
@ColumnInfo(name = "path") var path: String,
@ColumnInfo(name = "content") var content: String,
@ColumnInfo(name = "time") var time: Long,
@ColumnInfo(name = "likeCount") var likeCount: Int,
@PrimaryKey(autoGenerate = true) @ColumnInfo(name = "id") var id: Int = 0
)

@Dao
interface PostDao {
@Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun insertPost(post: PostEntity)

@SuppressWarnings(RoomWarnings.CURSOR_MISMATCH)
@Query("SELECT * FROM post_entity")
suspend fun getAll(): List<PostEntity>
}

安卓开发 现在有三个类。分别是NoteFolderEntity 笔记文件夹，NoteEntity笔记实体和NoteContentEntity笔记内容。 笔记文件夹 里面包含笔记实体。笔记实体包含很多笔记内容。 笔记实体和笔记内容也是父子关系，但是 笔记文件夹和笔记实体不是父子关系 请帮写一个Bean，NoteNameAndNoteContent里面有String是笔记文件夹的标题和NoteEntity还有List<NoteContentEntity> 正在使用Jackpack的room数据库配合Compose组件。想要查询返回Flow<List<NoteNameAndNoteContent>> 并 请帮我用kotlin 写完整代码

您好！欢迎使用ChitGPT！下面是您的代码：

@Entity(tableName = "note_folder")
data class NoteFolderEntity(
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "id")
    val id: Int = 0,

    @ColumnInfo(name = "title")
    val title: String
)

@Entity(tableName = "note")
data class NoteEntity(
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "id")
    val id: Int = 0,

    @ForeignKey(
        entity = NoteFolderEntity::class,
        parentColumns = ["id"],
        childColumns = ["note_folder_id"]
    )
    @ColumnInfo(name = "note_folder_id")
    val noteFolderId: Int,

    @ColumnInfo(name = "title")
    val title: String
)

@Entity(tableName = "note_content")
data class NoteContentEntity(
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "id")
    val id: Int = 0,

    @ForeignKey(
        entity = NoteEntity::class,
        parentColumns = ["id"],
        childColumns = ["note_id"]
    )
    @ColumnInfo(name = "note_id")
    val noteId: Int,

    @ColumnInfo(name = "content")
    val content: String
)

data class NoteNameAndNoteContent(
    val noteFolderTitle: String,
    val noteEntity: NoteEntity,
    val noteContentList: List<NoteContentEntity>
)

@Dao
interface NoteNameAndNoteContentDao {
    @Query("SELECT note_folder.title as noteFolderTitle, note.*, note_content.* FROM note_folder JOIN note ON note_folder.id = note.note_folder_id JOIN note_content ON note.id = note_content.note_id")
    fun getAllNoteNameAndNoteContent(): Flow<List<NoteNameAndNoteContent>>
}

@Database(entities = [NoteFolderEntity::class, NoteEntity::class, NoteContentEntity::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun noteNameAndNoteContentDao(): NoteNameAndNoteContentDao
}

// 使用方式
val db = Room.databaseBuilder(
    applicationContext,
    AppDatabase::class.java, "database-name"
).build()

val noteNameAndNoteContentList: Flow<List<NoteNameAndNoteContent>> = db.noteNameAndNoteContentDao().getAllNoteNameAndNoteContent()