feat: Add Kotlin MainApplication and suspend initialization support

Examples/OneSignalDemo/app/build.gradle

@@ -1,5 +1,6 @@
 plugins {
     id 'com.android.application'
+    id 'kotlin-android'
 }
 
 android {
@@ -61,6 +62,20 @@ android {
         exclude 'androidsupportmultidexversion.txt'
     }
 
+    // Exclude deprecated Java MainApplication from compilation to prevent conflicts
+    sourceSets {
+        main {
+            java {
+                exclude '**/MainApplication.java'
+            }
+        }
+    }
+
+    // Alternative approach: exclude from all source sets
+    android.sourceSets.all { sourceSet ->
+        sourceSet.java.exclude '**/MainApplication.java'
+    }
+
     task flavorSelection() {
         def tasksList = gradle.startParameter.taskRequests.toString()
         if (tasksList.contains('Gms')) {
@@ -74,6 +89,7 @@ android {
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlinVersion"
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.6.4'
     implementation 'androidx.multidex:multidex:2.0.1'
     implementation 'androidx.cardview:cardview:1.0.0'
     implementation 'androidx.appcompat:appcompat:1.5.1'

Examples/OneSignalDemo/app/src/huawei/AndroidManifest.xml

@@ -5,7 +5,7 @@
     package="com.onesignal.sdktest">
 
     <application
-        android:name=".application.MainApplication">
+        android:name=".application.MainApplicationKT">
 
         <service
           android:name="com.onesignal.sdktest.notification.HmsMessageServiceAppLevel"

Examples/OneSignalDemo/app/src/main/AndroidManifest.xml

@@ -20,7 +20,7 @@
     <uses-permission android:name="android.permission.WAKE_LOCK" />
 
     <application
-        android:name=".application.MainApplication"
+        android:name=".application.MainApplicationKT"
         android:allowBackup="true"
         android:icon="@mipmap/ic_onesignal_launcher"
         android:label="@string/app_name"

Examples/OneSignalDemo/app/src/main/java/com/onesignal/sdktest/application/MainApplication.java

@@ -33,18 +33,29 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
+/**
+ * @deprecated This Java implementation is deprecated. Use {@link MainApplicationKT} instead.
+ * The Kotlin version provides better async handling and modern coroutines support.
+ * 
+ * NOTE: This file is excluded from compilation in build.gradle to prevent conflicts.
+ * It's kept for reference only and will be removed in a future version.
+ */
+@Deprecated(since = "5.4.0", forRemoval = true)
 public class MainApplication extends MultiDexApplication {
     private static final int SLEEP_TIME_TO_MIMIC_ASYNC_OPERATION = 2000;
 
     public MainApplication() {
         // run strict mode to surface any potential issues easier
         StrictMode.enableDefaults();
+        Log.w(Tag.LOG_TAG, "MainApplication (Java) is deprecated. Please use MainApplicationKT (Kotlin) instead.");
     }
 
     @SuppressLint("NewApi")
     @Override
     public void onCreate() {
         super.onCreate();
+        Log.w(Tag.LOG_TAG, "DEPRECATED: Using MainApplication (Java). Please migrate to MainApplicationKT (Kotlin) for better async support.");
+
         OneSignal.getDebug().setLogLevel(LogLevel.DEBUG);
 
         // OneSignal Initialization

Examples/OneSignalDemo/app/src/main/java/com/onesignal/sdktest/application/MainApplicationKT.kt

@@ -0,0 +1,154 @@
+package com.onesignal.sdktest.application
+
+/**
+ * Modern Kotlin implementation of MainApplication.
+ * 
+ * This replaces the deprecated MainApplication.java with:
+ * - Better async handling using Kotlin Coroutines
+ * - Modern OneSignal API usage
+ * - Cleaner code structure
+ * - Proper ANR prevention
+ * 
+ * @see MainApplication (deprecated Java version)
+ */
+import android.annotation.SuppressLint
+import android.os.StrictMode
+import android.util.Log
+import androidx.annotation.NonNull
+import androidx.multidex.MultiDexApplication
+import com.onesignal.OneSignal
+import com.onesignal.debug.LogLevel
+import com.onesignal.inAppMessages.IInAppMessageClickEvent
+import com.onesignal.inAppMessages.IInAppMessageClickListener
+import com.onesignal.inAppMessages.IInAppMessageDidDismissEvent
+import com.onesignal.inAppMessages.IInAppMessageDidDisplayEvent
+import com.onesignal.inAppMessages.IInAppMessageLifecycleListener
+import com.onesignal.inAppMessages.IInAppMessageWillDismissEvent
+import com.onesignal.inAppMessages.IInAppMessageWillDisplayEvent
+import com.onesignal.notifications.IDisplayableNotification
+import com.onesignal.notifications.INotificationClickEvent
+import com.onesignal.notifications.INotificationClickListener
+import com.onesignal.notifications.INotificationLifecycleListener
+import com.onesignal.notifications.INotificationWillDisplayEvent
+import com.onesignal.sdktest.R
+import com.onesignal.sdktest.constant.Tag
+import com.onesignal.sdktest.constant.Text
+import com.onesignal.sdktest.notification.OneSignalNotificationSender
+import com.onesignal.sdktest.util.SharedPreferenceUtil
+import com.onesignal.user.state.IUserStateObserver
+import com.onesignal.user.state.UserChangedState
+import com.onesignal.user.state.UserState
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+
+class MainApplicationKT : MultiDexApplication() {
+    init {
+        // run strict mode to surface any potential issues easier
+        StrictMode.enableDefaults()
+    }
+
+    @SuppressLint("NewApi")
+    override fun onCreate() {
+        super.onCreate()
+        OneSignal.Debug.logLevel = LogLevel.DEBUG
+
+        // OneSignal Initialization
+        var appId = SharedPreferenceUtil.getOneSignalAppId(this)
+        // If cached app id is null use the default, otherwise use cached.
+        if (appId == null) {
+            appId = getString(R.string.onesignal_app_id)
+            SharedPreferenceUtil.cacheOneSignalAppId(this, appId)
+        }
+
+        OneSignalNotificationSender.setAppId(appId)
+
+        // Initialize OneSignal asynchronously on background thread to avoid ANR
+        CoroutineScope(Dispatchers.IO).launch {
+            val success = OneSignal.initWithContextSuspend(this@MainApplicationKT, appId)
+            Log.d(Tag.LOG_TAG, "OneSignal async init success: $success")
+
+            if (success) {
+                // Set up all OneSignal listeners after successful async initialization
+                setupOneSignalListeners()
+
+                // Request permission - this will internally switch to Main thread for UI operations
+                OneSignal.Notifications.requestPermission(true)
+            }
+        }
+
+        Log.d(Tag.LOG_TAG, Text.ONESIGNAL_SDK_INIT)
+    }
+
+    private fun setupOneSignalListeners() {
+        OneSignal.InAppMessages.addLifecycleListener(object : IInAppMessageLifecycleListener {
+            override fun onWillDisplay(@NonNull event: IInAppMessageWillDisplayEvent) {
+                Log.v(Tag.LOG_TAG, "onWillDisplayInAppMessage")
+            }
+
+            override fun onDidDisplay(@NonNull event: IInAppMessageDidDisplayEvent) {
+                Log.v(Tag.LOG_TAG, "onDidDisplayInAppMessage")
+            }
+
+            override fun onWillDismiss(@NonNull event: IInAppMessageWillDismissEvent) {
+                Log.v(Tag.LOG_TAG, "onWillDismissInAppMessage")
+            }
+
+            override fun onDidDismiss(@NonNull event: IInAppMessageDidDismissEvent) {
+                Log.v(Tag.LOG_TAG, "onDidDismissInAppMessage")
+            }
+        })
+
+        OneSignal.InAppMessages.addClickListener(object : IInAppMessageClickListener {
+            override fun onClick(event: IInAppMessageClickEvent) {
+                Log.v(Tag.LOG_TAG, "INotificationClickListener.inAppMessageClicked")
+            }
+        })
+
+        OneSignal.Notifications.addClickListener(object : INotificationClickListener {
+            override fun onClick(event: INotificationClickEvent) {
+                Log.v(Tag.LOG_TAG, "INotificationClickListener.onClick fired" +
+                        " with event: " + event)
+            }
+        })
+
+        OneSignal.Notifications.addForegroundLifecycleListener(object : INotificationLifecycleListener {
+            override fun onWillDisplay(@NonNull event: INotificationWillDisplayEvent) {
+                Log.v(Tag.LOG_TAG, "INotificationLifecycleListener.onWillDisplay fired" +
+                        " with event: " + event)
+
+                val notification: IDisplayableNotification = event.notification
+
+                //Prevent OneSignal from displaying the notification immediately on return. Spin
+                //up a new thread to mimic some asynchronous behavior, when the async behavior (which
+                //takes 2 seconds) completes, then the notification can be displayed.
+                event.preventDefault()
+                val r = Runnable {
+                    try {
+                        Thread.sleep(SLEEP_TIME_TO_MIMIC_ASYNC_OPERATION.toLong())
+                    } catch (ignored: InterruptedException) {
+                    }
+
+                    notification.display()
+                }
+
+                val t = Thread(r)
+                t.start()
+            }
+        })
+
+        OneSignal.User.addObserver(object : IUserStateObserver {
+            override fun onUserStateChange(@NonNull state: UserChangedState) {
+                val currentUserState: UserState = state.current
+                Log.v(Tag.LOG_TAG, "onUserStateChange fired " + currentUserState.toJSONObject())
+            }
+        })
+
+        OneSignal.InAppMessages.paused = true
+        OneSignal.Location.isShared = false
+    }
+
+    companion object {
+        private const val SLEEP_TIME_TO_MIMIC_ASYNC_OPERATION = 2000
+    }
+}

Examples/OneSignalDemo/build.gradle

@@ -13,6 +13,7 @@ buildscript {
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:8.8.2'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
         classpath 'com.google.gms:google-services:4.3.10'
         classpath 'com.huawei.agconnect:agcp:1.9.1.304'
 

OneSignalSDK/onesignal/core/src/main/java/com/onesignal/IOneSignal.kt

@@ -130,4 +130,100 @@ interface IOneSignal {
      * data is not cleared.
      */
     fun logout()
+
+    // Suspend versions of property accessors and methods to avoid blocking threads
+
+    /**
+     * Initialize the OneSignal SDK, suspend until initialization is completed
+     *
+     * @param context The Android context the SDK should use.
+     * @param appId The application ID the OneSignal SDK is bound to.
+     *
+     * @return true if the SDK could be successfully initialized, false otherwise.
+     */
+    suspend fun initWithContextSuspend(
+        context: Context,
+        appId: String? = null,
+    ): Boolean
+
+    /**
+     * Get the session manager without blocking the calling thread.
+     * Suspends until the SDK is initialized.
+     */
+    suspend fun getSession(): ISessionManager
+
+    /**
+     * Get the notifications manager without blocking the calling thread.
+     * Suspends until the SDK is initialized.
+     */
+    suspend fun getNotifications(): INotificationsManager
+
+    /**
+     * Get the location manager without blocking the calling thread.
+     * Suspends until the SDK is initialized.
+     */
+    suspend fun getLocation(): ILocationManager
+
+    /**
+     * Get the in-app messages manager without blocking the calling thread.
+     * Suspends until the SDK is initialized.
+     */
+    suspend fun getInAppMessages(): IInAppMessagesManager
+
+    /**
+     * Get the user manager without blocking the calling thread.
+     * Suspends until the SDK is initialized.
+     */
+    suspend fun getUser(): IUserManager
+
+    // Suspend versions of configuration properties for thread-safe access
+
+    /**
+     * Get the consent required flag in a thread-safe manner.
+     */
+    suspend fun getConsentRequired(): Boolean
+
+    /**
+     * Set the consent required flag in a thread-safe manner.
+     */
+    suspend fun setConsentRequired(required: Boolean)
+
+    /**
+     * Get the consent given flag in a thread-safe manner.
+     */
+    suspend fun getConsentGiven(): Boolean
+
+    /**
+     * Set the consent given flag in a thread-safe manner.
+     */
+    suspend fun setConsentGiven(value: Boolean)
+
+    /**
+     * Get the disable GMS missing prompt flag in a thread-safe manner.
+     */
+    suspend fun getDisableGMSMissingPrompt(): Boolean
+
+    /**
+     * Set the disable GMS missing prompt flag in a thread-safe manner.
+     */
+    suspend fun setDisableGMSMissingPrompt(value: Boolean)
+
+    /**
+     * Login a user with external ID and optional JWT token (suspend version).
+     * Handles initialization automatically.
+     *
+     * @param externalId The external ID of the user that is to be logged in.
+     * @param jwtBearerToken The optional JWT bearer token generated by your backend to establish
+     * trust for the login operation.  Required when identity verification has been enabled.
+     * See [Identity Verification | OneSignal](https://documentation.onesignal.com/docs/identity-verification)
+     */
+    suspend fun loginSuspend(
+        externalId: String,
+        jwtBearerToken: String? = null,
+    )
+
+    /**
+     * Logout the current user (suspend version).
+     */
+    suspend fun logoutSuspend()
 }