android - 房间 "cannot find implementation for"即使使用 kapt

Question

我正在尝试在我的项目中使用 Room。 Gradle 同步文件很好，但在尝试获取数据库实例时出现 RunitomeException。

“原因:java.lang.RuntimeException:找不到 com.fillooow.android.testtochka.BusinessLogic.database.GithubUserSearchDataBase 的实现。GithubUserSearchDataBase_Impl 不存在”

我搜索了这个问题，发现解决方案是将这行添加到 build.gradle 文件中:

implementation "android.arch.persistence.room:runtime:1.1.1"
implementation "android.arch.persistence.room:rxjava2:1.1.1"
kapt "android.arch.persistence.room:compiler:1.1.1"

同时应用这个插件

apply plugin: 'kotlin-kapt'

但这是我的 build.gradle 文件，我仍然有这个问题:

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'


android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.fillooow.android.testtochka"
        minSdkVersion 21
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
        buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:support-v4:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.squareup.retrofit2:converter-gson:2.5.0'
    implementation 'com.squareup.retrofit2:retrofit:2.5.0'
    implementation 'io.reactivex.rxjava2:rxandroid:2.1.0'
    implementation 'com.squareup.retrofit2:adapter-rxjava2:2.5.0'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.jakewharton.rxbinding2:rxbinding-kotlin:2.0.0'
    implementation 'com.google.android.gms:play-services-auth:16.0.1'
    implementation 'com.facebook.android:facebook-android-sdk:[4,5)'
    implementation 'com.vk:androidsdk:1.6.9'
    implementation 'com.android.support:cardview-v7:28.0.0'
    implementation 'com.squareup.picasso:picasso:2.71828'
    implementation "android.arch.persistence.room:runtime:1.1.1"
    implementation "android.arch.persistence.room:rxjava2:1.1.1"
    kapt "android.arch.persistence.room:compiler:1.1.1"
}

这是数据库类

import android.arch.persistence.room.Room
import android.arch.persistence.room.RoomDatabase
import android.content.Context

abstract class GithubUserSearchDataBase : RoomDatabase(){

    abstract fun githubUserSearchDataDao(): GithubUserSearchDataDao

    companion object {
        private var INSTANCE: GithubUserSearchDataBase? = null

        fun getInstance(context: Context): GithubUserSearchDataBase?{
            if (INSTANCE == null){
                synchronized(GithubUserSearchDataBase::class){
                    INSTANCE = Room.databaseBuilder(context.applicationContext,
                        GithubUserSearchDataBase::class.java,
                        "github.db")
                    .build()
                }
            }
            return INSTANCE
        }

        fun destroyInstance(){
            INSTANCE = null
        }
    }
}

项目多次清理和重建。那么，也许我错过了什么？

Answer 1

您的 gradle 文件看起来不错。添加正确的导入后，一定要同步它。

您缺少的是数据库类顶部的 @Database 注释。

@Database(entities = [Entity1::class, Entity2::class, Entity3::class, Entity4::class], version = 1)
abstract class GithubUserSearchDataBase : RoomDatabase(){

    abstract fun githubUserSearchDataDao(): GithubUserSearchDataDao

    companion object {
        private var INSTANCE: GithubUserSearchDataBase? = null

        fun getInstance(context: Context): GithubUserSearchDataBase?{
            if (INSTANCE == null){
                synchronized(GithubUserSearchDataBase::class){
                    INSTANCE = Room.databaseBuilder(context.applicationContext,
                        GithubUserSearchDataBase::class.java,
                        "github.db")
                    .build()
                }
            }
            return INSTANCE
        }

        fun destroyInstance(){
            INSTANCE = null
        }
    }
}

在 @Database 注释的 entities 属性中，您必须放置一个数组，其中包含用 @Entity 注释的模型的所有类注解。我放假名，你应该放正确的。