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Overview

Android push notifications are essential for driving sustained user engagement and retention in your Android app. They empower you to deliver real-time updates, reminders, and personalized messages directly to your users, improving the overall user experience and stickiness of your app. OneSignal leverages Firebase Cloud Messaging (FCM) but is designed to provide even more flexibility and functionality as shown in this guide.

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Requirements

• Android 7.0+ device or emulator with “Google Play Store (Services)” installed.
• Android Studio (setup instructions use Android Studio Meerkat).
• Configured OneSignal app and platform.

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Configure your OneSignal app and platform

Required setup for push notifications

To start sending push notifications with OneSignal, you must first configure your OneSignal app with all the platforms your support—Apple (APNs), Google (FCM), Huawei (HMS), and/or Amazon (ADM).

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Android setup

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1. Add the OneSignal SDK

In Android Studio, open your build.gradle.kts (Module: app) or build.gradle (Module: app) file and add OneSignal to your dependencies.

implementation("com.onesignal:OneSignal:[5.1.6, 5.1.99]")

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Sync Gradle

After adding the dependency, sync your project:

• Click Sync Now in the banner
• Or go to File > Sync Project with Gradle Files

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2. Initialize SDK in the Application class

It’s best practice to initialize OneSignal in the onCreate method of your Application class to ensure proper SDK setup across all entry points.

In your ApplicationClass, initialize OneSignal with the provided methods.

Replace YOUR_APP_ID with your OneSignal App ID found Settings > Keys & IDs in your OneSignal dashboard. If you don’t have access to the OneSignal app, ask your Team Members to invite you.

package com.your.package.name // Replace with your package name

import android.app.Application
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch

import com.onesignal.OneSignal
import com.onesignal.debug.LogLevel
  
class ApplicationClass : Application() {
   override fun onCreate() {
      super.onCreate()
        
      // Enable verbose logging for debugging (remove in production)
      OneSignal.Debug.logLevel = LogLevel.VERBOSE
      // Initialize with your OneSignal App ID
      OneSignal.initWithContext(this, "YOUR_APP_ID")
      // Use this method to prompt for push notifications.
      // We recommend removing this method after testing and instead use In-App Messages to prompt for notification permission.
      CoroutineScope(Dispatchers.IO).launch {
         OneSignal.Notifications.requestPermission(true)
      }
   }
}

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3. Customize default icons

We recommend configuring your notification icons to match your app’s branding. Otherwise, OneSignal will use a default bell icon.

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Testing the OneSignal SDK integration

This guide helps you verify that your OneSignal SDK integration is working correctly by testing push notifications, subscription registration, and in-app messaging.

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Check mobile subscriptions

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Set up test subscriptions

Test subscriptions are helpful for testing a push notification before sending a message.

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Send test push via API

curl -X \
POST --url 'https://api.onesignal.com/notifications' \
 --header 'content-type: application/json; charset=utf-8' \
 --header 'authorization: Key YOUR_APP_API_KEY' \
 --data \
 '{
  "app_id": "YOUR_APP_ID",
  "target_channel": "push",
  "name": "Testing basic setup",
  "headings": {
  	"en": "👋"
  },
  "contents": {
    "en": "Hello world!"
  },
  "included_segments": [
    "Test Users"
  ],
  "ios_attachments": {
    "onesignal_logo": "https://avatars.githubusercontent.com/u/11823027?s=200&v=4"
  },
  "big_picture": "https://avatars.githubusercontent.com/u/11823027?s=200&v=4"
}'

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Send an in-app message

In-app messages let you communicate with users while they are using your app.

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User identification

Previously, we demonstrated how to create mobile Subscriptions. Now we’ll expand to identifying Users across all their subscriptions (including push, email, and SMS) using the OneSignal SDK. We’ll cover External IDs, tags, multi-channel subscriptions, privacy, and event tracking to help you unify and engage users across platforms.

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Assign External ID

Use an External ID to identify users consistently across devices, email addresses, and phone numbers using your backend’s user identifier. This ensures your messaging stays unified across channels and 3rd party systems (especially important for Integrations).

Set the External ID with our SDK’s login method each time they are identified by your app.

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Add data tags

Tags are key-value pairs of string data you can use to store user properties (like username, role, or preferences) and events (like purchase_date, game_level, or user interactions). Tags power advanced Message Personalization and Segmentation allowing for more advanced use cases.

Set tags with our SDK addTag and addTags methods as events occur in your app.

In this example, the user reached level 6 identifiable by the tag called current_level set to a value of 6.

We can create a segment of users that have a level of between 5 and 10, and use that to send targeted and personalized messages:

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Add email and/or SMS subscriptions

Earlier we saw how our SDK creates mobile subscriptions to send push and in-app messages. You can also reach users through emails and SMS channels by creating the corresponding subscriptions.

• Use the addEmail method to create email subscriptions.
• Use the addSms method to create SMS subscriptions.

If the email address and/or phone number already exist in the OneSignal app, the SDK will add it to the existing user, it will not create duplicates.

You can view unified users via Audience > Users in the dashboard or with the View user API.

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Privacy & user consent

To control when OneSignal collects user data, use the SDK’s consent gating methods:

• setConsentRequired(true): Prevents data collection until consent is given.
• setConsentGiven(true): Enables data collection once consent is granted.

See our Privacy & security docs for more on:

• Data collected by the SDK
• Handling personal data

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Prompt for push permissions

Instead of calling requestPermission() immediately on app open, take a more strategic approach. Use an in-app message to explain the value of push notifications before requesting permission.

For best practices and implementation details, see our Prompt for push permissions guide.

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Listen to push, user, and in-app events

Use SDK listeners to react to user actions and state changes.

The SDK provides several event listeners for you to hook into. See our SDK reference guide for more details.

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Push notification events

• addClickListener(): Detect when a notification is tapped. Helpful for Deep Linking.
• addForegroundLifecycleListener(): Control how notifications behave in foreground.

For full customization, see Mobile Service Extensions.

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User state changes

• addObserver() for user state: Detect when the External ID is set.
• addPermissionObserver(): Track the user’s specific interaction with the native push permission prompt.
• addObserver() for push subscription: Track when the push subscription status changes.

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In-app message events

• addClickListener(): Handle in-app click actions. Ideal for deep linking or tracking events.
• addLifecycleListener(): Track full lifecycle of in-app messages (shown, clicked, dismissed, etc.).

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Advanced setup & capabilities

Explore more capabilities to enhance your integration:

• 🔁 Migrating to OneSignal from another service
• 🌍 Location tracking
• 🔗 Deep Linking
• 🔌 Integrations
• 🧩 Mobile Service Extensions
• 🛎️ Action buttons
• 🌐 Multi-language messaging
• 🛡️ Identity Verification
• 📊 Custom Outcomes
• 📲 Live Activities

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Mobile SDK setup & reference

Make sure you’ve enabled all key features by reviewing the Mobile push setup guide.

For full details on available methods and configuration options, visit the Mobile SDK reference.

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Custom Notification Layout

Android 12 and higher enforce system templates for custom notifications. However, you can still customize your layout using Android’s standard notification styles.

To customize your layout:

• Follow Android’s custom notification guide
• Apply changes via the Notification Service Extension

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Disable default open behavior

When a notification is clicked, OneSignal will resume your app, or open your launcher Activity if your app was swiped away. To prevent OneSignal from auto-opening your launcher Activity when a notification is clicked, add this to your AndroidManifest.xml:

  <application ...>
     <meta-data android:name="com.onesignal.NotificationOpened.DEFAULT" android:value="DISABLE" />
  </application>

You must implement a custom Notification Opened Listener in the onCreate method in your Application class. You will need to call startActivity from this callback to take the user to your intended Activity.

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Background data and push overrides

• Use the Notification Service Extension to handle background data or override notification visuals
• Use the SDK Notification Event Handlers to read additional data from a notification

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Right-to-Left (RTL) language support

To support RTL languages in notifications and UI, add this to your AndroidManifest.xml:

  <application
    android:supportsRtl="true"
    ...
  </application>