房间找不到实施

Question

我在测试Room数据库时遇到问题:当我运行测试时,我得到以下异常:

java.lang.RuntimeException: cannot find implementation for database.TicketDatabase. TicketDatabase_Impl does not exist
at android.arch.persistence.room.Room.getGeneratedImplementation(Room.java:92)
at android.arch.persistence.room.RoomDatabase$Builder.build(RoomDatabase.java:454)
at com.sw.ing.gestionescontrini.DatabaseTest.setDatabase(DatabaseTest.java:36)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:59)
at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:262)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1886)

类DatabaseTest:

public class DatabaseTest {

    TicketDatabase database;
    DAO ticketDAO;


    @Before
    public void setDatabase() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        Context context = InstrumentationRegistry.getTargetContext();
        database = Room.inMemoryDatabaseBuilder(context, TicketDatabase.class).build();

        Method method = TicketDatabase.class.getDeclaredMethod("ticketDao()");
        method.setAccessible(true);
        ticketDAO = (DAO) method.invoke(database, null);
    }
}

gradle文件:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    buildToolsVersion '26.0.2'
    defaultConfig {
        applicationId "com.sw.ing.gestionescontrini"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    defaultConfig {
        multiDexEnabled true
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:26.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'

    annotationProcessor 'android.arch.lifecycle:compiler:1.0.0'
    compile 'android.arch.persistence.room:rxjava2:1.0.0-rc1'
    testCompile'android.arch.persistence.room:testing:1.0.0-rc1'

}

我真的不知道这个实现应该是什么,我搜索了一个解决方案,但我发现的所有内容对我都不起作用.例如,许多人发现了添加kapt"android.arch.persistence.room ..."的解决方案,但gradle不承认"kapt".

Answer 1

kapt 是为了Kotlin.

首先,添加:

annotationProcessor "android.arch.persistence.room:compiler:1.0.0"

到你的dependencies关闭.

然后,升级android.arch.persistence.room:rxjava2和android.arch.persistence.room:testing对1.0.0替代1.0.0-rc1.

Answer 2

对于Kotlin,在gradle文件中将'annotationProcessor'关键字更改为'kapt'.

kapt "android.arch.persistence.room:compiler:1.1.1"

并在依赖文件的顶部添加

apply plugin: 'kotlin-kapt'

Answer 3

java.lang.RuntimeException：找不到 com.example.kermovie.data.repository.local.MoviesDatabase 的实现。MoviesDatabase_Impl 不存在

您必须将以下内容添加到您的build.gradle：

apply plugin: 'kotlin-kapt' 

dependencies {
    implementation 'androidx.room:room-runtime:2.3.0'
    implementation "androidx.room:room-ktx:2.3.0"
    kapt "androidx.room:room-compiler:2.3.0"
}

当有新版本可用时，您可能需要更改版本。

Answer 4

如果您使用Kotlin，请确保您的in档文件中存在此代码。

apply plugin: "kotlin-kapt"

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

文档：https : //developer.android.com/jetpack/androidx/releases/room

Answer 5

将其添加到您的应用程序模块的buld.gradle文件中

    //The Room persistence library provides an abstraction layer over SQLite
    def room_version = "2.3.0"
    implementation("androidx.room:room-runtime:$room_version")
    annotationProcessor "androidx.room:room-compiler:$room_version"

在您的数据访问对象文件中添加以下注释

@Database(entities = [EntityClassName::class], version = 1)

根据您的项目需要替换实体类名称和数据库版本代码。

如果您使用 kotlin，请将 kapt 插件应用到注释处理器，如下行：

apply plugin: 'kotlin-kapt'

然后替换annotationProcessor "androidx.room:room-compiler:$room_version"为以下行：

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

Answer 6

我看到这里的一些人（Vishu Bhardwaj 和其他类似 StackOverflow 问题的人）抱怨接受的答案对他们不起作用。我认为值得一提的是，我在 MULTI 模块项目中遇到了类似的问题，需要围绕已接受的答案进行技巧。

在我的多模块项目中，房间数据库依赖项主要包含在一个基本模块中，并使用适当的 api 符号导出，但房间代码分为 2 个不同的模块。项目编译时没有警告，但java.lang.RuntimeException: cannot find implementation for database...在运行时引发。

这是通过添加修复的

annotationProcessor "android.arch.persistence.room:compiler:$room_version"

在包含 Room 相关代码的所有模块中。