未解决的参考：viewModels()

Question

我刚刚启动了一个 Android 应用程序，我想使用 ViewModel。我查看了文档并放置了Lifecycle 中的所有依赖项，但是当我尝试实例化像此视图这样的视图模型时，MyViewModel by viewModels()我收到此错误“未解析的引用：viewModels()”。

这些是依赖项：

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.core:core-ktx:1.2.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.13'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

    def lifecycle_version = "2.2.0"
    def arch_version = "2.1.0"

    implementation "android.arch.lifecycle:extensions:1.1.1"
    kapt "android.arch.lifecycle:compiler:1.1.1"

    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
    implementation "androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version"
    implementation "androidx.lifecycle:lifecycle-runtime-ktx:$lifecycle_version"
    implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:$lifecycle_version"

    kapt "androidx.lifecycle:lifecycle-compiler:$lifecycle_version"

    implementation "androidx.lifecycle:lifecycle-service:$lifecycle_version"
    implementation "androidx.lifecycle:lifecycle-process:$lifecycle_version"

    implementation "androidx.lifecycle:lifecycle-reactivestreams-ktx:$lifecycle_version"
    testImplementation "androidx.arch.core:core-testing:$arch_version"

}

Answer 1

将此包含在您的依赖项中，

implementation "android.arch.lifecycle:extensions:1.1.1"

然后，apply plugin: 'kotlin-kapt'在build.gradle中添加

然后加，

kapt "android.arch.lifecycle:compiler:1.1.1"

将其他替换annotationProcessor为kapt

看看是否有效，如果无效，则转到

文件->使缓存无效并重新启动