使用 Hilt 将依赖项注入 Android 类时无法运行

Question

I'm in the process of making an application using Hilt. But my question is, am I only able to run my app through AndroidManifest.xml? I'd like to run it through another class, but it keeps giving me a blank page.

My Classes:

Application class using @HiltAndroidApp

@HiltAndroidApp
class ExampleApplication : Application()

Activity class using @AndroidEntryPoint

@AndroidEntryPoint
class ExampleActivity : ComponentActivity() {
    @RequiresApi(Build.VERSION_CODES.N)
    override fun onCreate(instance: Bundle?) {
        super.onCreate(instance)
        setContent {
            AppTheme {
                Surface() {
                 ......

Manifest.xml (This is the only way I can run the class, ExampleActivity).

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:name=".ui.ExampleApplication"
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.App"
        tools:targetApi="31">
        <activity
            android:name=".ExampleActivity"
            android:exported="true"
            android:label="@string/app_name"
            android:theme="@style/Theme.App">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
    </application>

</manifest>

So, I've tried calling my application from another class, but I can't call ExampleActivity.kt alone, so I tried calling two classes, but it keeps giving me a blank page.

Here's what I've tried:

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            AppTheme {
                 ExampleApplication()
                 ExampleActivity()
            }
        }
    }
}

It gives a blank screen.

I will create another class and make it my start class, where I will then call ExampleApplication and ExampleActivity.

How am I supposed to call two classes using Hilt dependencies from another class?

Of course, I have updated the manifest.xml so that it says.MainActivity.

Answer 1

First of all, why do you need Hilt? What are you trying to Inject and where?

ExampleApplication() is just a place where you configure app-wide settings, you are never supposed to call it from somewhere else, so you don't need that line.

Furthermore, Which activity are you trying to start? MainActivity or ExampleActivity()? Calling ExampleActivity within MainActivity won't have any effect.

SetContent {... } is the place where you create the UI.

If you want to open another activity from MainActivity then you need to implement navigation or use Intents.