kotlin - Unresolved reference : RoomDatabase

Question

我正在尝试在我的应用程序中设置房间(按照文档)。除了我的 Database 类外，一切都编译得很好。找不到 RoomDatabase 类。可能值得注意的是，我使用的是 Jetpack Compose 桌面应用程序，而不是在 Android 上。

import androidx.room.*

@Entity
data class User(
    @PrimaryKey val uid: Int,
    @ColumnInfo(name = "first_name") val firstName: String?,
    @ColumnInfo(name = "last_name") val lastName: String?
)


@Dao
interface UserDao {
    @Query("SELECT * FROM user")
    fun getAll(): List<User>

    @Query("SELECT * FROM user WHERE uid IN (:userIds)")
    fun loadAllByIds(userIds: IntArray): List<User>

    @Query("SELECT * FROM user WHERE first_name LIKE :first AND " +
            "last_name LIKE :last LIMIT 1")
    fun findByName(first: String, last: String): User

    @Insert
    fun insertAll(vararg users: User)

    @Delete
    fun delete(user: User)
}

@Database(entities = arrayOf(User::class), version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}

plugins {
    id 'org.jetbrains.kotlin.jvm' version '1.4.10'
}

apply plugin: 'kotlin-kapt'

group 'org.example'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
    google()
    jcenter()
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib"
    def room_version = "2.2.5"
    implementation 'androidx.core:core-ktx:1.2.0'

    implementation "androidx.room:room-runtime:$room_version"
    kapt "androidx.room:room-compiler:$room_version"

    // optional - Kotlin Extensions and Coroutines support for Room
    implementation "androidx.room:room-ktx:$room_version"

}

Answer 1

问题是所有内容都在一个文件中。您需要创建一个 User.kt 文件:

@Entity
data class User(
    @PrimaryKey val uid: Int,
    @ColumnInfo(name = "first_name") val firstName: String?,
    @ColumnInfo(name = "last_name") val lastName: String?
)

然后，一个 UserDao kotlin 文件:

@Dao
interface UserDao {
    @Query("SELECT * FROM user")
    fun getAll(): List<User>

    @Query("SELECT * FROM user WHERE uid IN (:userIds)")
    fun loadAllByIds(userIds: IntArray): List<User>

    @Query("SELECT * FROM user WHERE first_name LIKE :first AND " +
           "last_name LIKE :last LIMIT 1")
    fun findByName(first: String, last: String): User

    @Insert
    fun insertAll(vararg users: User)

    @Delete
    fun delete(user: User)
}

然后是应用数据库kotlin文件:

@Database(entities = arrayOf(User::class), version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}

我的建议是遵循this tutorial .它将教您基础知识并引导您完成一个完整的应用程序。祝你好运:)