Wrong tab indicator in ViewPager / TabLayout support libraries when dynamically deleting tabs

Question

Wrong tab indicator in ViewPager / TabLayout support libraries when dynamically deleting tabs

OK, I was working with new Support Library

ViewPager

and TabLayout

, and in my application I dynamically add and remove tabs based on what the user SearchView

was open / closed.

My work execution; however, an indicator appears with a tab indicator. The correct slice of the tab is displayed, but the tab indicator is under the wrong tab.

I tested a lot to check if this was my problem, but then I thought it was a bug in the support library. I submitted a bug report to Google , but the status of the report was marked asuserError.

So a google developer gave me an idea of what to do. I tried the fix; however, nothing to fix. I've done some independent testing in the last few hours based on what he said the correct behavior depends on whether ViewPager

OnPageChangedListener

.

I added more information to my bug report, but since it was flagged as userError, I don't know if the developer will answer. That is why I am here now.

Screen recording

Here is the screen recording of the problem {NOTE: Clicking this link will automatically load the screen recording [. mp4] }. Pay attention to the indicator of the tab. It should go to the previous displayed tab, but it doesn't.

Questions

1. Correct indicator, incorrect displayed fragment

    @Override
    public boolean onMenuItemActionCollapse(final MenuItem item) {

        clearAllTabs();
        addTabs(displayedTabs);

        viewPager.setCurrentItem(previousTabPosition, true);

        tabLayout.removeAllTabs();
        tabLayout.setupWithViewPager(viewPager);

        return true;

    }

StackTrace:

First go to the second tab, click on SearchView, then close SearchView ....

On MenuItemCompat.OnActionExpandListener::onMenuItemActionCollapse(...)

    clearAllTabs()           [A, B, C, Search] -> []
    addTabs(displayedTabs)   [] -> [A, B, C]

    ViewPager.OnPageChangeListener::OnPageSelected(2)
    ViewPager.OnPageChangeListener::OnPageScrolled(2, 0.0, 0)

    viewPager.setCurrentItem(1, true)

    ViewPager.OnPageChangeListener::onPageScrollStateChanged(2)
    ViewPager.OnPageChangeListener::onPageSelected(1)

    tabLayout.removeAllTabs()
    tabLayout.setupWithViewPager(viewPager);

    ViewPager.OnPageChangeListener::onPageSelected(0) [NOTE: this statement does not fire if Tab A was displayed before opening SearchView]

    return true

    ViewPager.OnPageChangeListener::onPageScrolled(0, 0.0, 0)

    // UI display is updated (Tab 1 fragment is displayed, but tab indicator is on 2nd Tab)

    ViewPager.OnPageChangeListener::onPageScrollStateChanged(0)

2. Correct displayed snippet, incorrect tab indicator

    @Override
    public boolean onMenuItemActionCollapse(final MenuItem item) {

        clearAllTabs();
        addTabs(displayedTabs);

        tabLayout.removeAllTabs();
        tabLayout.setupWithViewPager(viewPager);

        viewPager.setCurrentItem(previousTabPosition, true);

        return true;

    }

StackTrace:

First go to the second tab, click on SearchView, then close SearchView ....

On MenuItemCompat.OnActionExpandListener::onMenuItemActionCollapse(...)
    clearAllTabs()           [A, B, C, Search] -> []
    addTabs(displayedTabs)   [] -> [A, B, C]

    ViewPager.OnPageChangeListener::OnPageSelected(2)
    ViewPager.OnPageChangeListener::OnPageScrolled(2, 0.0, 0)

    tabLayout.removeAllTabs()
    tabLayout.setupWithViewPager(viewPager);

    ViewPager.OnPageChangeListener::onPageScrollStateChanged(2)
    ViewPager.OnPageChangeListener::onPageSelected(0)

    viewPager.setCurrentItem(1, true)

    ViewPager.OnPageChangeListener::onPageSelected(1)

    return true

    ViewPager.OnPageChangeListener::onPageScrolled(1, 0.0, 0)

    // UI display is updated (Tab 2 fragment is displayed, but tab indicator is on 3rd Tab)

    ViewPager.OnPageChangeListener::onPageScrollStateChanged(0)