Notifications in Android with Example

package org.geeksforgeeks.demo;

import android.Manifest;
import android.annotation.SuppressLint;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.os.Build;
import android.os.Bundle;
import android.widget.Button;
import android.widget.RemoteViews;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.app.NotificationCompat;
import androidx.core.app.NotificationManagerCompat;

public class MainActivity extends AppCompatActivity {

    private final String channelId = "i.apps.notifications"; // Unique channel ID for notifications
    private final String description = "Test notification";  // Description for the notification channel
    private final int notificationId = 1234; // Unique identifier for the notification

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

        Button btn = findViewById(R.id.btn);

        // Create a notification channel (required for Android 8.0 and higher)
        createNotificationChannel();

        btn.setOnClickListener(v -> {
            // Request runtime permission for notifications on Android 13 and higher
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                if (ActivityCompat.checkSelfPermission(this, Manifest.permission.POST_NOTIFICATIONS) 
                    != PackageManager.PERMISSION_GRANTED) {

                    ActivityCompat.requestPermissions(
                            this,
                            new String[]{Manifest.permission.POST_NOTIFICATIONS},
                            101
                    );
                    return;
                }
            }
            sendNotification(); // Trigger the notification
        });
    }

    /**
     * Create a notification channel for devices running Android 8.0 or higher.
     * A channel groups notifications with similar behavior.
     */
    private void createNotificationChannel() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel notificationChannel = new NotificationChannel(
                    channelId,
                    description,
                    NotificationManager.IMPORTANCE_HIGH
            );
            notificationChannel.enableLights(true); // Turn on notification light
            notificationChannel.setLightColor(Color.GREEN);
            notificationChannel.enableVibration(true); // Allow vibration for notifications

            NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
            if (notificationManager != null) {
                notificationManager.createNotificationChannel(notificationChannel);
            }
        }
    }

    /**
     * Build and send a notification with a custom layout and action.
     */
    @SuppressLint("MissingPermission")
    private void sendNotification() {
        // Intent that triggers when the notification is tapped
        Intent intent = new Intent(this, AfterNotification.class);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
        PendingIntent pendingIntent = PendingIntent.getActivity(
                this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_IMMUTABLE
        );

        // Custom layout for the notification content
        RemoteViews contentView = new RemoteViews(getPackageName(), R.layout.activity_after_notification);

        // Build the notification
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, channelId)
                .setSmallIcon(R.drawable.gfg_logo) // Notification icon
                .setContent(contentView) // Custom notification content
                .setContentTitle("Hello") // Title displayed in the notification
                .setContentText("Welcome to GeeksforGeeks!!") // Text displayed in the notification
                .setContentIntent(pendingIntent) // Pending intent triggered when tapped
                .setAutoCancel(true) // Dismiss notification when tapped
                .setPriority(NotificationCompat.PRIORITY_HIGH); // Notification priority for better visibility

        // Display the notification
        NotificationManagerCompat notificationManager = NotificationManagerCompat.from(this);
        notificationManager.notify(notificationId, builder.build());
    }
}