没有 @Inject 构造函数或 @Provides-annotated 方法就无法提供 Dagger/MissingBinding

Question

我正在尝试在 android kotlin 中学习 Dagger/Hilt 依赖注入。我准备了一个简单的小应用程序。当我运行应用程序时，出现以下错误：

C:\XXXXX\AndroidLearning\MyTest\app\build\generated\hilt\component_sources\debug\com\example\mytest\MyTest_HiltComponents.java:125: error: [Dagger/MissingBinding] com.example.mytest.MyTestInjectionClass cannot be provided without an @Inject constructor or an @Provides-annotated method.
  public abstract static class SingletonC implements MyTest_GeneratedInjector,
                         ^
      com.example.mytest.MyTestInjectionClass is injected at
          com.example.mytest.MyViewModel(myTestInjectionClass)
      com.example.mytest.MyViewModel is injected at
          com.example.mytest.MyViewModel_HiltModules.BindsModule.binds(arg0)
      @dagger.hilt.android.internal.lifecycle.HiltViewModelMap java.util.Map<java.lang.String,javax.inject.Provider<androidx.lifecycle.ViewModel>> is requested at
          dagger.hilt.android.internal.lifecycle.HiltViewModelFactory.ViewModelFactoriesEntryPoint.getHiltViewModelMap() [com.example.mytest.MyTest_HiltComponents.SingletonC ? com.example.mytest.MyTest_HiltComponents.ActivityRetainedC ? com.example.mytest.MyTest_HiltComponents.ViewModelC]

在我的应用程序中，viewModel 类使用

@HiltViewModel

注释进行注释。我也有

@Inject

视图模型类构造函数的注释。我正在注入一个名为“MyInjectionClass”的类。我创建了一个模块，并在其中用“@Provides”和“@Singleton”注释了函数。我正在包含应用程序中的文件

项目build.gradle文件

buildscript {
    ext {
        compose_version = '1.2.0'
    }
}// Top-level build file where you can add configuration options common to all sub-projects/modules.
plugins {
    id 'com.android.application' version '7.4.0' apply false
    id 'com.android.library' version '7.4.0' apply false
    id 'org.jetbrains.kotlin.android' version '1.7.0' apply false
    id("com.google.dagger.hilt.android") version "2.44" apply false
}

app build.gradle 文件

plugins {
    id 'com.android.application'
    id 'org.jetbrains.kotlin.android'
    id("kotlin-kapt")
    id("dagger.hilt.android.plugin")
}

android {
    namespace 'com.example.mytest'
    compileSdk 33

    defaultConfig {
        applicationId "com.example.mytest"
        minSdk 29
        targetSdk 33
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        vectorDrawables {
            useSupportLibrary true
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
    buildFeatures {
        compose true
    }
    composeOptions {
        kotlinCompilerExtensionVersion '1.2.0'
    }
    packagingOptions {
        resources {
            excludes += '/META-INF/{AL2.0,LGPL2.1}'
        }
    }
}

dependencies {
    def lifecycle_version = "2.5.1"
    def retrofit_version = "2.9.0"
    def gson_version = "2.9.0"
    def room_version = "2.5.0"
    def nav_version = "2.5.3"
    def compose_version = "1.3.3"
    def preference_version = "1.2.0"

    implementation 'androidx.core:core-ktx:1.7.0'
    implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.3.1'
    implementation 'androidx.activity:activity-compose:1.3.1'
    implementation "androidx.compose.ui:ui:$compose_version"
    implementation "androidx.compose.ui:ui-tooling-preview:$compose_version"
    implementation 'androidx.compose.material3:material3:1.0.0-alpha11'


    // Dagger - hilt
    implementation 'com.google.dagger:hilt-android:2.44.2'
    kapt 'com.google.dagger:hilt-compiler:2.44.2'
    implementation 'androidx.hilt:hilt-navigation-compose:1.0.0'

    //lifecycle
    // ViewModel
    implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version")
    // ViewModel utilities for Compose
    implementation("androidx.lifecycle:lifecycle-viewmodel-compose:$lifecycle_version")

    implementation("androidx.lifecycle:lifecycle-runtime-compose:2.6.0-alpha03")

    implementation "androidx.compose.runtime:runtime-livedata:$compose_version"
    implementation("androidx.compose.runtime:runtime:$compose_version")

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

    //couroutines
    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.9")
    implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version")
    implementation("androidx.lifecycle:lifecycle-runtime-ktx:$lifecycle_version")
    implementation("androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version")

    //navigation in compose
    implementation("androidx.navigation:navigation-compose:$nav_version")


    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.5'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
    androidTestImplementation "androidx.compose.ui:ui-test-junit4:$compose_version"
    debugImplementation "androidx.compose.ui:ui-tooling:$compose_version"
    debugImplementation "androidx.compose.ui:ui-test-manifest:$compose_version"

mainactivity.kt 文件

@AndroidEntryPoint
class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        setContent {
            MyTestTheme {
                val myViewModel = hiltViewModel<MyViewModel>()
                val myText1 = myViewModel.myText.observeAsState()
                val myText2 = ""
                // A surface container using the 'background' color from the theme
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {

                    Text(myText1.value!!.myText!!)
                    TextField(value = myText2, onValueChange = {myViewModel.testFunction(myText2)})

                }
            }
        }
    }
}

MyViewModel.kt 文件

@HiltViewModel
class MyViewModel @Inject constructor(
    private val myTestInjectionClass: MyTestInjectionClass
) : ViewModel() {
    var temp = MyModel()
    var myText = MutableLiveData<MyModel?>(temp)



    fun testFunction(text:String) = viewModelScope.launch {
        myText.value = myTestInjectionClass.execute(text)
    }
}

MyTest是应用类

@HiltAndroidApp
class MyTest : Application() {
}

我的模型.kt

data class MyModel(
    var myText: String? = ""
)

MyTestInjectionClass.kt

class MyTestInjectionClass() {

    suspend fun execute(text:String) : MyModel {
        delay(2000)
        var myModel = MyModel()
        myModel.myText =text.uppercase()
        return myModel;
    }
}

一个测试模块.kt

@Module
@InstallIn(SingletonComponent::class)
class MyTestModule {
    @Singleton
    @Provides
    suspend fun  provideAMyTestInjectionClass() : MyTestInjectionClass {
        return MyTestInjectionClass()
    }

}

有人可以帮我解决这个错误吗？谢谢

Answer 1

当我删除

MyTestModule.kt

文件中的函数之前的 suspend 关键字时，它起作用了

@Module
@InstallIn(SingletonComponent::class)
class MyTestModule {
    @Singleton
    @Provides
    fun  provideAMyTestInjectionClass() : MyTestInjectionClass {
        return MyTestInjectionClass()
    }

}
~~~