Android Code Snippet Setting up a foreground Bluetooth service on Android 12/13+ (SDK 36)

Struggling to get BT to work on SDK 36, and with some help of my friend Chat, we finally got it to work. I asked Chat to resume the points you have to pay attention to, if you want BT get to work on android 14+ Note: you dont need all the permissions as listed here, but Chat took my manifest to report.

Setting up a foreground Bluetooth service on Android 12/13+ (SDK 36)​

1. Manifest Service Declaration
Use AddApplicationText to declare the service with the correct foregroundServiceType attributes:

AddApplicationText(
  <service
      android:name=".blth"
      android:enabled="true"
      android:exported="false"
      android:foregroundServiceType="dataSync|connectedDevice"/>
)

• dataSync is commonly needed for general foreground operations.
• connectedDevice is required for Bluetooth-connected foreground services.
• Do not include parentheses or quotes incorrectly—must be valid XML.
• 2. Permissions
  Make sure you declare all necessary permissions for Bluetooth and foreground operation:
  
  AddPermission(android.permission.ACCESS_FINE_LOCATION)
  AddPermission(android.permission.BLUETOOTH_ADVERTISE)
  AddPermission(android.permission.BLUETOOTH_CONNECT)
  AddPermission(android.permission.BLUETOOTH_SCAN)
  AddPermission(android.permission.REQUEST_INSTALL_PACKAGES)
  AddPermission(android.permission.ACCESS_COARSE_LOCATION)
  AddPermission(android.permission.ACCESS_MOCK_LOCATION)
  AddPermission("android.permission.FOREGROUND_SERVICE")
  AddPermission("android.permission.FOREGROUND_SERVICE_CONNECTED_DEVICE")
  AddPermission(android.permission.ACCESS_NETWORK_STATE)
  AddPermission("android.permission.RECEIVE_BOOT_COMPLETED") 'for starting service after reboot
  AddPermission("android.permission.BIND_JOB_SERVICE")
  • FOREGROUND_SERVICE_CONNECTED_DEVICE is mandatory for SDK 36+ if using foregroundServiceType="connectedDevice".
  • 
    
  • 
    

  ---

  
  3. Service Start Implementation (B4A)
  
  
  When starting the service, use a JavaObject to call startForeground with the correct type:
• [*]Sub Service_Start (StartingIntent As Intent)
      If AStream.IsInitialized Then AStream.Close
      AStream.InitializePrefix(Main.serial1.InputStream, False, Main.serial1.OutputStream, "AStream")
  
      Notification1.Initialize
      Notification1.Icon = "icon"
      Notification1.Vibrate = False
      Notification1.AutoCancel = True
      Notification1.Sound = False
      Notification1.SetInfo(Main.progname, Main.ProgVersion, Main)
  
      Dim jo As JavaObject
      jo.InitializeContext
  
      If Sys.Sdk >= 29 Then
          ' Android 10 (API 29) ''method with 3 parameters
          Dim args(3) As Object
          args(0) = 1
          args(1) = Notification1
          args(2) = 16 ' FOREGROUND_SERVICE_TYPE_CONNECTED_DEVICE
          jo.RunMethod("startForeground", args)
      Else
          ' older versions, method with 2 parameters
          Dim args(2) As Object
          args(0) = 1
          args(1) = Notification1
          jo.RunMethod("startForeground", args)
      End If
  
      Log("BT service start")
  End Sub
  [*]
• • args(2) = 4 corresponds to FOREGROUND_SERVICE_TYPE_CONNECTED_DEVICE.
  • Make sure the notification is initialized before starting foreground.

  ---

  
  4. Common Pitfalls
  • Manifest Parsing Errors: Avoid wrapping the XML in parentheses or extra quotes in AddApplicationText.
  • Foreground Service Crash: Happens if foregroundServiceType in manifest does not match the type used in startForeground.
  • Missing Permissions: SDK 31+ enforces FOREGROUND_SERVICE_CONNECTED_DEVICE for Bluetooth-connected services.
  • Initialization: JavaObject.InitializeContext must use context, not Me.

  ---

  
  5. Notes
  • Tested on SDK 36 / Android 14: service starts correctly, no crash, and Bluetooth connection works.
  • Optional: consider handling auto-reconnect and updating notifications to keep the service robust.

 

[b4x-de]

Thank you for sharing this. Do you have an working example, that you can provide as source code? This might help us to learn from it.

 

[MbedAndroid]

follow erel's example and modifiy the necessary items. Here i got the bluetooth start i use, i dont have a testproject.
--->EDIT Modified the examples for compatible older devices

Sub mnuSearchDevices_Click
    If CheckLocationEnabled = False Then Return
    
    foundDevices.Clear
    
    Dim NeededPermissions As List
    NeededPermissions.Initialize
    
    If Sys.Sdk >= 31 Then
        ' Android 12+
        NeededPermissions.Add("android.permission.BLUETOOTH_SCAN")
        NeededPermissions.Add("android.permission.BLUETOOTH_CONNECT")
    Else
        ' Android 11 of lager
        NeededPermissions.Add(rp.PERMISSION_ACCESS_FINE_LOCATION)
        NeededPermissions.Add("android.permission.BLUETOOTH")
        NeededPermissions.Add("android.permission.BLUETOOTH_ADMIN")
    End If
    
    RequestNextPermission(NeededPermissions)
End Sub

Sub RequestNextPermission(Permissions As List)
    If Permissions.Size = 0 Then
        StartDiscoverySafe
        Return
    End If

    Dim perm As String = Permissions.Get(0)
    Permissions.RemoveAt(0)

    rp.CheckAndRequest(perm)
    Wait For Activity_PermissionResult (Permission As String, result1 As Boolean)

    If result1 = False Then
        ToastMessageShow("Permission denied: " & Permission, False)
        Return
    End If

    RequestNextPermission(Permissions)
End Sub

Sub CancelDiscoveryIfRunning
    Dim adapter As JavaObject
    adapter = adapter.InitializeStatic("android.bluetooth.BluetoothAdapter").RunMethod("getDefaultAdapter", Null)
    If adapter.IsInitialized Then
        Dim discovering As Boolean = adapter.RunMethod("isDiscovering", Null)
        If discovering Then
            adapter.RunMethod("cancelDiscovery", Null)
            Sleep(150) ' short pause
        End If
    End If
End Sub

Sub StartDiscoverySafe
    If admin.IsInitialized = False Then
        admin.Initialize("admin")
    End If

    If admin.IsInitialized = False Then
        MsgboxAsync(loca.Localize("BTDEVICENOTCOMPATIBLE"), loca.Localize("ERROR"))
        Return
    End If

    ' first stop discovery if it was already running
    CancelDiscoveryIfRunning

    Dim ok As Boolean = admin.StartDiscovery
    If ok = False Then
        ' second try might help after failing the first one
        CancelDiscoveryIfRunning
        Sleep(150)
        ok = admin.StartDiscovery
    End If

    If ok = False Then
        ToastMessageShow(loca.Localize("ERRORDISCOVERY"), True)
    Else
        ProgressDialogShow(loca.Localize("SEARCHDEVICE") & "...")
    End If
End Sub