Android Code Snippet Haptic feedback in B4A: 4 approaches compared

I recently went down a rabbit hole comparing the different ways to trigger haptic feedback (vibration) in B4A, and ended up decompiling Phone.jar (CFR) and reading the .b4xlib source of XUI Views directly, instead of guessing. Sharing the findings here in case it saves someone else the trouble.

Four approaches, all Android:

	VIBRATE permission	Needs a View	Cross-platform
A. PhoneVibrate	YES	NO	NO
B. performHaptic	NO	YES	NO
C. VibrationEffect	YES	NO	NO
D. XUIViewsUtils	NO	YES	YES

A. Phone library — PhoneVibrate.Vibrate(TimeMs)​

'Alternative: .Vibrate(TimeMs As Long) on the PhoneVibrate object
'from the Phone library (needs android.permission.VIBRATE)
I decompiled Phone.jar to see what's actually inside. This is the real implementation:

public static class Phone.PhoneVibrate {
    public static void Vibrate(BA ba, long TimeMs) {
        Vibrator v = (Vibrator) ba.context.getSystemService("vibrator");
        v.vibrate(TimeMs);
    }
}

It's a bare call to the legacy Vibrator.vibrate(long), no attributes, no settings check whatsoever in the code. Two things worth knowing if you use this:

• On a LongClick, if your listener returns True, Android automatically fires its own performHapticFeedback(LONG_PRESS) right after your Sub runs — and that second vibration overrides yours. So your custom TimeMs is only respected on a plain Click, not on a LongClick (where you get the system's fixed long-press pattern instead, same as option B).
  
• Empirically, both the Click and the LongClick paths only vibrate if the system's "haptic feedback" setting is enabled — even though the decompiled code shows no such check. So this gating happens at the Android framework/OEM level for the unattributed legacy call, not in B4A code.

B. Manual JavaObject — performHapticFeedback​

Public Sub TriggerHapticLongPress(v As View)
        Try
                ' performHapticFeedback flags (per AOSP HapticFeedbackConstants):
                ' 0 = LONG_PRESS   (press-and-hold feedback)
                ' 1 = VIRTUAL_KEY  (standard tap feedback)   <- flag actually used below
                ' 3 = KEYBOARD_TAP (very light feedback)
                Dim jo As JavaObject = v
                jo.RunMethod("performHapticFeedback", Array As Object(1))
        Catch
                Log("Error triggering haptic feedback: " & LastException)
        End Try
End Sub

No permission needed. Respects both View.hapticFeedbackEnabled and the system's touch-feedback setting, per Android docs.

C. Manual JavaObject — VibrationEffect (full control)​

Private Sub TriggerHapticFeedback
        Try
                Dim sdkInt As Int = GetSdkInt
                Dim ctx As JavaObject
                ctx.InitializeContext
                Dim duration As Long = 150
                Dim amplitude As Int = -1
                Dim effect As JavaObject
                effect = effect.InitializeStatic("android.os.VibrationEffect") _
                        .RunMethod("createOneShot", Array As Object(duration, amplitude))

                If sdkInt >= 31 Then
                        ' VibratorManager -> getDefaultVibrator
                        ' (sdkInt >= 33 additionally uses VibrationAttributes.createForUsage)

                Else If sdkInt >= 26 Then
                        ' Vibrator.vibrate(effect)
                Else
                        ' Vibrator.vibrate(legacyDuration)  ' same call as option A
                End If

        Catch
                Log("Vibration error: " & LastException.Message)
        End Try
End Sub

Needs VIBRATE permission and 3–4 SDK branches to maintain, but it's the only option that gives you real control over duration/amplitude while explicitly ignoring the "haptic feedback" system setting (it only respects Silent/DND).

D. XUI Views — XUIViewsUtils.PerformHapticFeedback​

Depends on XUI (per the library's own manifest.txt: B4A.DependsOn=BitmapCreator, XUI, DateUtils, xCustomListView, IME, JavaObject, B4XFormatter). I unzipped the .b4xlib (it's just a zip) and read XUIViewsUtils.bas directly — no decompiling needed, it's plain source:

Public Sub PerformHapticFeedback (View As B4XView)
    Initialize
   #if B4A
    Dim jo As JavaObject = View
    jo.RunMethod("performHapticFeedback", Array(1))
    #Else if B4i
    If FeedbackGenerator.IsInitialized Then
        FeedbackGenerator.RunMethod("impactOccurred", Null)
    End If
    #end if
End Sub

On Android, this is functionally identical to option B — same method, same flag, no extra settings logic. The only real reason to use it over your own implementation is the #if B4i branch, which uses UIImpactFeedbackGenerator natively on iOS. Usage:

' A plain B4A View works here thanks to the XUI dependency
Sub btnConfirm_Click
        XUIViewsUtils.PerformHapticFeedback(btnConfirm)
End Sub

Checking the setting before vibrating (for A, B, D)​

Since A, B and D all depend on the system's haptic feedback setting, this pair of Subs checks it and can send the user to the right settings screen:

' Checks whether touch feedback is enabled in the system settings
Public Sub IsHapticFeedbackEnabled As Boolean
        Try
                Dim ctxt As JavaObject
                ctxt.InitializeContext
                Dim cr As JavaObject = ctxt.RunMethod("getContentResolver", Null)
                Dim settingsSystem As JavaObject
                settingsSystem.InitializeStatic("android.provider.Settings$System")

                Dim hapticOn As Int = settingsSystem.RunMethod( _
                        "getInt", Array As Object(cr, "haptic_feedback_enabled", 0))
                Return hapticOn = 1
        Catch
                Log("Error reading haptic feedback state: " & LastException)
                Return True ' Assume True when in doubt, to avoid false warnings
        End Try
End Sub

' Opens Android's sound/vibration settings screen
Public Sub OpenHapticSettings
        Dim ctxt As JavaObject
        ctxt.InitializeContext

        Dim actions() As String = Array As String( _
                "android.settings.SOUND_SETTINGS", _
                "android.settings.VIBRATION_SETTINGS", _
                "android.provider.Settings.ACTION_SOUND_SETTINGS", _
                "android.settings.SETTINGS" _
        )

        For Each act As String In actions
                If TryStartIntent(ctxt, act) Then
                        Return
                End If
        Next

        ToastMessageShow("Could not open settings automatically", False)
End Sub

Private Sub TryStartIntent(ctxt As JavaObject, actionName As String) As Boolean
        Try
                Dim joIntent As JavaObject
                joIntent.InitializeNewInstance("android.content.Intent", Array(actionName))
                joIntent.RunMethod("addFlags", Array(0x10000000)) ' FLAG_ACTIVITY_NEW_TASK
                ctxt.RunMethod("startActivity", Array(joIntent))
                Return True
        Catch
                Return False
        End Try
End Sub

Doesn't add any permission (it's a read-only getInt) or dependency beyond JavaObject, which all four options already use. Usage pattern:

If HapticManager.IsHapticFeedbackEnabled Then
        ' trigger the vibration normally
Else
        ' optional: warn the user or call HapticManager.OpenHapticSettings
End If

Note this check doesn't add anything useful for option C — it explicitly ignores that setting, so testing it wouldn't change its behaviour.

TL;DR​

• Want the simplest, permission-free option and don't care about the exact pattern → B.
• Want full control over duration/amplitude and don't want it gated by the haptic-feedback setting → C, at the cost of maintaining SDK branches.
• Building for Android + iOS → D (identical to B on Android, native on iOS).
• A doesn't offer any verified advantage over B or D: it needs an extra permission and, on top of that, still ends up gated by the same system setting.

Happy to share the full write-up (with the decompiled bytecode and the .bas source side by side) if anyone wants more detail.

 

[Erel]

1 Better not to post decompiled code. In the case of Phone library it is simple - the code is available here: https://github.com/AnywhereSoftware/B4A/tree/master/Libs_Phone/src/anywheresoftware/b4a/phone

2. My recommendation is actually D. Simple, part of a common library, and cross platform.

 

[GeoT]

Ok.
Thanks, Erel.
So, to be more specific, Option A would be:

Dim pv As PhoneVibrate
pv.Vibrate(100)

 

[GeoT]

Oops! I see.
The Java code is in that GitHub repository.
Thanks.