use foreground service for android version >= 26

build.gradle

@@ -7,7 +7,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.0.0'
+        classpath 'com.android.tools.build:gradle:7.1.0'
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
     }
@@ -16,7 +16,7 @@ apply plugin: 'java-library'
 
 ext{
 
-    compileSdkVersion = 24
+    compileSdkVersion = 31
     buildToolsVersion = '23.0.3'
 
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 #Tue Dec 07 18:39:23 IST 2021
 distributionBase=GRADLE_USER_HOME
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.0.2-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.2-bin.zip
 distributionPath=wrapper/dists
 zipStorePath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME

org.eclipse.paho.android.service/build.gradle

@@ -9,7 +9,7 @@ android {
 
     defaultConfig {
         minSdkVersion 9
-        targetSdkVersion 24
+        targetSdkVersion 31
 
         testApplicationId "org.eclipse.paho.android.service.test"
     }

org.eclipse.paho.android.service/src/main/java/org/eclipse/paho/android/service/MqttAndroidClient.java

@@ -48,12 +48,14 @@
 import org.eclipse.paho.client.mqttv3.MqttToken;
 import org.eclipse.paho.client.mqttv3.internal.wire.MqttWireMessage;
 
+import android.app.Notification;
 import android.content.BroadcastReceiver;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.ServiceConnection;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.IBinder;
 import android.support.v4.content.LocalBroadcastManager;
@@ -157,6 +159,10 @@ public void onServiceDisconnected(ComponentName name) {
 	private volatile boolean receiverRegistered = false;
 	private volatile boolean bindedService = false;
 
+	// Foreground notification
+	private int foregroundServiceNotificationId = 1;
+	private Notification foregroundServiceNotification;
+
 	/**
 	 * Constructor - create an MqttAndroidClient that can be used to communicate with an MQTT server on android
 	 *
@@ -412,7 +418,25 @@ public IMqttToken connect(MqttConnectOptions options, Object userContext,
 		if (mqttService == null) { // First time - must bind to the service
 			Intent serviceStartIntent = new Intent();
 			serviceStartIntent.setClassName(myContext, SERVICE_NAME);
-			Object service = myContext.startService(serviceStartIntent);
+			Object service = null;
+			if (Build.VERSION.SDK_INT >= 26 && foregroundServiceNotification != null) {
+				serviceStartIntent.putExtra(
+						MqttService.PAHO_MQTT_FOREGROUND_SERVICE_NOTIFICATION,
+						foregroundServiceNotification);
+				serviceStartIntent.putExtra(
+						MqttService.PAHO_MQTT_FOREGROUND_SERVICE_NOTIFICATION_ID,
+						foregroundServiceNotificationId);
+				service = myContext.startForegroundService(serviceStartIntent);
+			} else {
+				try {
+					service = myContext.startService(serviceStartIntent);
+				} catch (Exception e) {
+					IMqttActionListener listener = token.getActionCallback();
+					if (listener != null) {
+						listener.onFailure(token, e);
+					}
+				}
+			}
 			if (service == null) {
 				IMqttActionListener listener = token.getActionCallback();
 				if (listener != null) {
@@ -1782,4 +1806,15 @@ public void registerResources(Context context){
 	public void sendNoWait(MqttWireMessage message, MqttToken token) throws MqttException {
 		mqttService.sendNoWait(clientHandle, message, token);
 	}
+
+	/**
+	 *
+	 * @param notification - ForegroundServiceNotification
+	 * @param id - ID of the foreground service notification.
+	 *
+	 */
+	public void setForegroundService(Notification notification, int id) {
+		this.foregroundServiceNotification = notification;
+		this.foregroundServiceNotificationId = id;
+	}
 }

org.eclipse.paho.android.service/src/main/java/org/eclipse/paho/android/service/MqttService.java

@@ -31,6 +31,7 @@
 import org.eclipse.paho.client.mqttv3.internal.wire.MqttWireMessage;
 
 import android.annotation.SuppressLint;
+import android.app.Notification;
 import android.app.Service;
 import android.content.BroadcastReceiver;
 import android.content.Context;
@@ -230,6 +231,9 @@ public class MqttService extends Service implements MqttTraceHandler {
     // Identifier for Intents, log messages, etc..
     static final String TAG = "MqttService";
 
+    static final String PAHO_MQTT_FOREGROUND_SERVICE_NOTIFICATION = MqttService.class.getSimpleName() + ".FOREGROUND_SERVICE_NOTIFICATION_ID";
+    static final String PAHO_MQTT_FOREGROUND_SERVICE_NOTIFICATION_ID = MqttService.class.getSimpleName() + ".FOREGROUND_SERVICE_NOTIFICATION";
+
     // callback id for making trace callbacks to the Activity
     // needs to be set by the activity as appropriate
     private String traceCallbackId;
@@ -620,6 +624,15 @@ public int onStartCommand(final Intent intent, int flags, final int startId) {
         // run till explicitly stopped, restart when
         // process restarted
         registerBroadcastReceivers();
+        if (Build.VERSION.SDK_INT >= 26 && intent != null) {
+            Notification foregroundServiceNotification
+                    = (Notification) (intent.getParcelableExtra(PAHO_MQTT_FOREGROUND_SERVICE_NOTIFICATION));
+            if (foregroundServiceNotification != null)
+                startForeground(
+                        intent.getIntExtra(PAHO_MQTT_FOREGROUND_SERVICE_NOTIFICATION_ID, 1),
+                        foregroundServiceNotification
+                );
+        }
 
         return START_STICKY;
     }