(Android) Is there any way to show AlertDialog when firebase cloud message received (even when app is backgorund)?

Question

I want to show an AlertDialog when the Firebase cloud message received (and either the Android application is foreground or background).

In forground, the app shows the AlertDialog, but in background, the app doesn't show the AlertDialog.

MyFirebaseMessageService.kt

class MyFirebaseMessageService : FirebaseMessagingService() {
private val TAG = "fcm_tag"

override fun onMessageReceived(remoteMessage: RemoteMessage) {
    val title = remoteMessage.notification?.title
    val body = remoteMessage.notification?.body

    Log.d(TAG, "fcm title: $title")
    Log.d(TAG, "fcm body: $body")

    val alertDialogIntent = Intent(baseContext, AlertDialogActivity::class.java)
    alertDialogIntent.putExtra("title", title)
    alertDialogIntent.putExtra("body", body)

    try {
        PendingIntent.getActivity(
            baseContext,
            0,
            alertDialogIntent,
            PendingIntent.FLAG_IMMUTABLE
        ).send()
    } catch (e: Exception) {
        Log.d(TAG, "fcm error: $e")
    }
}
}

AlertDialogActivity.kt

class AlertDialogActivity : Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val bund = intent.extras
    val title = bund?.getString("title")
    val body = bund?.getString("body")

    AlertDialog.Builder(this).run {
        setTitle(title)
        setMessage(body)
        setPositiveButton("OK") { _, _ ->
            finish()
        }
        setCancelable(false)
        show()
    }
}
}

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"
    package="com.myproject">
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.MyProject">

        <service
            android:name=".MyFirebaseMessageService"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>

        <activity
            android:name=".AlertDialogActivity"
            android:exported="true"
            android:theme="@style/Theme.AppCompat.DayNight.Dialog">
        </activity>

        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:label="@string/app_name"
            android:theme="@style/Theme.MyProject">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <meta-data
            android:name="com.google.firebase.messaging.default_notification_channel_id"
            android:value="fcm_default_channel" />
        <meta-data
            android:name="com.google.firebase.messaging.default_notification_icon"
            android:resource="@drawable/ic_launcher_foreground" />
    </application>
</manifest>

Answer 1

AlertDialog alertDialog = new AlertDialog.Builder(this)
                    .setTitle("Title")
                    .setMessage("Are you sure?")
                    .create();

alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
alertDialog.show();

And ask for this permission

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />