ViewPager2: Can't select particular fragment programmatically

Question

I'm trying to select particular fragment say, 2nd or 3rd fragment in ViewPager2 programmatically. It's not working properly. Sometimes it works, sometimes not. Although It's working for TabLayout every time.

What I have tried:

I have tried using ViewPager2.post like paymentViewpager.post { paymentViewpager.currentItem = 1 }.
Tried adding paymentViewpager.setCurrentItem(tab.position, true) in TabLayoutMediator callback.
I have double checked that I'm calling paymentViewpager.setCurrentItem after adapter is being set.

Code is like below.

In onCreate of an Activity

if (!isGuestUser) {
        getPaymentMethod()
        viewModel.getMyProfile()
    } else {
        val adapter = SecureCheckoutPaymentSelectionAdapter(
                activity = this,
                callback = this,
                gPayCallback = this,
                paypalCallBack = this,
                cardPaymentList = arrayListOf(),
                gPayPaymentDetail = arrayListOf(),
                payPalPaymentDetail = arrayListOf(),
                isPaymentMethodPresent = false,
                itemsCount = THREE,
                userType = userType,
                isGuestUser
        )
        binding.includeSecureCheckoutPaymentDetails.paymentViewpager.adapter = adapter

        initTabLayout()
    }

private fun initTabLayout() {
    TabLayoutMediator(binding.includeSecureCheckoutPaymentDetails.paymentTab, binding.includeSecureCheckoutPaymentDetails.paymentViewpager) { tab, position ->
        val view = DataBindingUtil.inflate<LayoutTabImageBinding>(LayoutInflater.from(this), R.layout.layout_tab_image, tab.view, true)

        when (position) {
            0 -> {
                view.icon.setImageDrawable(ContextCompat.getDrawable(this, R.drawable.card_payment))
            }
            1 -> {
                view.icon.setBackgroundResource(R.drawable.google_pay_primary_logo)
            }
            else -> {
                view.icon.setImageDrawable(ContextCompat.getDrawable(this, R.drawable.paypal_card))
            }
        }
        tab.customView = view.root
        binding.includeSecureCheckoutPaymentDetails.paymentViewpager.setCurrentItem(tab.position, true)
    }.attach()
}

When API response comes after a while, I need to select 2nd Fragment of ViewPager2. Below code executes in that function.

val adapter = SecureCheckoutPaymentSelectionAdapter(
                                activity = this,
                                callback = this,
                                gPayCallback = this,
                                paypalCallBack = this,
                                cardPaymentList = if (userType == PERSONAL_USER_TYPE) paymentSavedResponse.personalCards as ArrayList<PaymentMethod>
                                else paymentSavedResponse.businessCards as ArrayList<PaymentMethod>,
                                gPayPaymentDetail = paymentSavedResponse.googlePay as ArrayList<GooglePay>,
                                payPalPaymentDetail = paymentSavedResponse.paypalAccount,
                                isPaymentMethodPresent = paymentSavedResponse.paymentMethodPresent,
                                itemsCount = THREE,
                                userType = userType,
                                isGuestUser
                        )
                        binding.includeSecureCheckoutPaymentDetails.paymentViewpager.adapter = adapter

                        initTabLayout()
                        setViewPagerClick()

                        if (paymentSavedResponse.latestPaymentDetails?.paymentMethodPresent == true) {
                            Log.e("mk", "in paymentMethodPresent == true...")
                            when {
                                paymentSavedResponse.latestPaymentDetails.paymentMethod.size > ZERO -> {
                                    Log.e("mk", "in card...")
                                    binding.includeSecureCheckoutPaymentDetails.apply {
                                        paymentViewpager.currentItem = ZERO
                                        //paymentTab.selectTab(paymentTab.getTabAt(ZERO))
                                    }
                                }
                                paymentSavedResponse.latestPaymentDetails.googlePay.size > ZERO -> {
                                    Log.e("mk", "in GPay...")
                                    binding.includeSecureCheckoutPaymentDetails.apply {
                                        paymentViewpager.currentItem = ONE
                                        //paymentTab.selectTab(paymentTab.getTabAt(ONE))
                                    }
                                }
                                else -> {
                                    Log.e("mk", "in Else...")
                                    binding.includeSecureCheckoutPaymentDetails.apply {
                                        paymentViewpager.currentItem = TWO
                                        //paymentTab.selectTab(paymentTab.getTabAt(TWO))
                                    }
                                }
                            }
                        }

I have came across same question here which is don't have accepted answer yet. Any help would be appreciated.

Zain · Answer 1 · 2021-04-27T12:50:23.803

4

I came across this with ViewPager2, for me the reason was enabling the smoothScroll (second parameter in setCurrentItem) as enabling it makes the ViewPager goes to a wrong page

So the fix was to disable it:

binding.includeSecureCheckoutPaymentDetails.paymentViewpager.setCurrentItem(tab.position, false)

edited Apr 27 '21 at 12:50

answered Apr 27 '21 at 12:45

Zain

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Okay. Let me know if you require any further information from my side. – Maulik Dodia Apr 27 '21 at 12:57
Can you try `paymentViewpager.postDelayed()` with some delay – Zain Apr 27 '21 at 13:05
I had tried, although let me try one more time. @Zain – Maulik Dodia Apr 27 '21 at 13:15
I have tried with 500 and 1000 milliseconds, it rarely doesn't work. Most of the times It is working. Is this a proper solution? @Zain – Maulik Dodia Apr 27 '21 at 13:43
No it should be something like 100msec or 200ms as max, greater than that shouldn't be proper solution, we just need to make sure that's not pending on any other UI thing in the main thread loop... there must be something else causing this – Zain Apr 27 '21 at 14:01
Okay. I will check with max 200ms. Thanks for the help. @Zain – Maulik Dodia Apr 27 '21 at 14:16
@MaulikDodia Can you also log down the `tab.position` and see if it's already correct before setting it to the `viewPager` – Zain Apr 27 '21 at 14:27
`tab.position` is everytime `-1` and I have noticed that It is with 500ms of delay, It is working like 80% of the times. Not all the time. @Zain – Maulik Dodia Apr 28 '21 at 04:50
Cool now we knew why the viewpager went to wrong fragment... Can you use *position* instead of *tab.position* – Zain Apr 28 '21 at 08:09
I will try and let you know. @Zain – Maulik Dodia Apr 28 '21 at 09:38

ViewPager2: Can't select particular fragment programmatically

1 Answers1