<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/inbox_style_notification"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="InboxStyle Notification"
        android:textColor="@android:color/white"
        android:backgroundTint="@color/colorPrimary"
        android:textAllCaps="false"
        android:layout_centerInParent="true"/>
</RelativeLayout>

                                    
                                  

                                    
                                        import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;
import androidx.core.app.NotificationManagerCompat;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity{

    Button button;
    private final String CHANNEL_ID = "inbox_style_notification";
    private final int NOTIFICATION_ID = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        button = findViewById(R.id.inbox_style_notification);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                createNotificationChannel();
                NotificationCompat.Builder builder = new NotificationCompat.Builder(MainActivity.this, CHANNEL_ID);
                builder.setSmallIcon(R.drawable.logo);
                builder.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.logo));
                builder.setContentTitle("4 New Messages");
                builder.setStyle(new NotificationCompat.InboxStyle()
                        .addLine("Hi there")
                        .addLine("How are you?")
                        .setSummaryText("+2 more"));
                builder.setPriority(NotificationCompat.PRIORITY_DEFAULT);

                NotificationManagerCompat notificationManagerCompat = NotificationManagerCompat.from(MainActivity.this);
                notificationManagerCompat.notify(NOTIFICATION_ID, builder.build());
            }
        });
    }

    private void createNotificationChannel(){
        if(Build.VERSION.SDK_INT>=Build.VERSION_CODES.O){

            CharSequence name = "InboxStyleNotification Notification";
            String description = "Include all the InboxStyleNotification notification";
            int importance = NotificationManager.IMPORTANCE_DEFAULT;

            NotificationChannel notificationChannel = new NotificationChannel(CHANNEL_ID, name, importance);
            notificationChannel.setDescription(description);

            NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
            notificationManager.createNotificationChannel(notificationChannel);
        }
    }
}
                                    
                                  

                                    
                                        import android.app.NotificationChannel
import android.app.NotificationManager
import android.content.Context
import android.graphics.BitmapFactory
import android.os.Build
import android.os.Bundle
import android.view.View
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.NotificationCompat
import androidx.core.app.NotificationManagerCompat

class MainActivity : AppCompatActivity() {

    private lateinit var button: Button
    private val CHANNEL_ID = "inbox_style_notification"
    private val NOTIFICATION_ID = 1

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

        button = findViewById(R.id.inbox_style_notification)

        button.setOnClickListener {
            createNotificationChannel()
            val builder = NotificationCompat.Builder(this, CHANNEL_ID)
            builder.setSmallIcon(R.drawable.logo)
            builder.setLargeIcon(BitmapFactory.decodeResource(resources, R.drawable.logo))
            builder.setContentTitle("4 New Messages")
            builder.setStyle(NotificationCompat.InboxStyle()
                .addLine("Hi there")
                .addLine("How are you?")
                .setSummaryText("+2 more"))
            builder.setPriority(NotificationCompat.PRIORITY_DEFAULT)

            val notificationManagerCompat = NotificationManagerCompat.from(this)
            notificationManagerCompat.notify(NOTIFICATION_ID, builder.build())
        }
    }

    private fun createNotificationChannel() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val name = "InboxStyleNotification Notification"
            val descriptionText = "Include all the InboxStyleNotification notification"
            val importance = NotificationManager.IMPORTANCE_DEFAULT
            val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
                description = descriptionText
            }

            val notificationManager =
                getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
            notificationManager.createNotificationChannel(channel)
        }
    }
}