Hilt 字段注入抛出 "property not initialized" 错误？

Question

我刚刚按照官方 Hilt 文档尝试实现了一个简单的字段注入，这里是 MainActivity：

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import dagger.hilt.EntryPoint
import dagger.hilt.android.AndroidEntryPoint
import javax.inject.Inject

@AndroidEntryPoint
class MainActivity : AppCompatActivity() {

    //field Injection
    @Inject lateinit var analytics: AnalyticsAdapter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        println(analytics.doAThing())
    }
}

class AnalyticsAdapter @Inject constructor() {
    fun doAThing(): String{
        return "Hello"
    }
}

我还有一个应用程序 class，它在我的清单中声明：

@HiltAndroidApp
class MyApplication: Application() {

}

这是它抛出的错误：

2021-07-23 01:24:11.686 32325-32325/com.example.hilt E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.hilt, PID: 32325
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hilt/com.example.hilt.MainActivity}: kotlin.UninitializedPropertyAccessException: lateinit property analytics has not been initialized
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
     Caused by: kotlin.UninitializedPropertyAccessException: lateinit property analytics has not been initialized
        at com.example.hilt.MainActivity.getAnalytics(MainActivity.kt:13)
        at com.example.hilt.MainActivity.onCreate(MainActivity.kt:19)
        at android.app.Activity.performCreate(Activity.java:8000)
        at android.app.Activity.performCreate(Activity.java:7984)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:223) 
        at android.app.ActivityThread.main(ActivityThread.java:7656) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

使用 2.38 版的 Hilt。

为什么最简单的东西不起作用-.-

Answer 1

两个小时后，我发现您的项目 build.gradle 文件的类路径行中的 hilt 版本应该较低：

从版本 2.38 降级到 2.28-alpha：

classpath 'com.google.dagger:hilt-android-gradle-plugin:2.28-alpha'

然后在应用 build.gradle 文件中继续使用版本 2.38:

implementation "com.google.dagger:hilt-android:2.38"
kapt "com.google.dagger:hilt-android-compiler:2.38"

在应用 build.gradle 文件中从 2.38 降级到 2.28-alpha 后，您必须清除设备上应用的缓存，否则它仍然会崩溃。

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