첫 번째로 띄울 화면 지정

AndroidManifest.xml

<?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: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.Ex_View"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="false" >
        </activity>
        <activity
            android:name=".MainActivity2"
            android:exported="true">

            <!--어플을 실행했을 때 첫번째로 띄울 화면 지정-->
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

어플을 실행시킬때 첫번째로 띄울화면 지정은 inten-filter 코드를 넣은쪽이 실행된다 android:exported="true"로 바꿔주고 비활성할곳은 false로 해야한다.

<activity
            android:name=".MainActivity"
            android:exported="false" >
        </activity>
        <activity
            android:name=".MainActivity2"
            android:exported="true">

            <!--어플을 실행했을 때 첫번째로 띄울 화면 지정-->
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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