Set selected tab indicator in Java code

Question

I have a NavigationView that I want to setup to work along with a ViewPager and a TabLayout.

A click on an item from the NavigationView shall :

1. Take the user to the corresponding fragment

2. Set the TabLayout indicator accordingly

I managed to accomplish the first task using mViewPager.setCurrentItem() but I am unable to fix the second one. I tried :

1. To retrieve the tab via the TabLayout and "select" it :

   mTabLayout.getTabAt(TAB_POSITION).select();
   

   but it was a bust. (Tab indicator)

2. to call mTabLayout.setupWithViewPager(mViewPager); after each click on an item but same result. (TabLayout tab selection).

EDIT - code :

    mViewPager = (ViewPager) findViewById(R.id.viewpager);
    mViewPager.setAdapter(mAdapter);
    mTabLayout = (TabLayout) findViewById(R.id.tablayout);
    mTabLayout.setupWithViewPager(mViewPager);

    mViewPager.addOnPageChangeListener(new PageChangeListener()); 

..... .....

class PageChangeListener implements ViewPager.OnPageChangeListener {

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

    }

    @Override
    public void onPageSelected(int position) {
        switch (position) {
            case 0:
                mTabLayout.getTabAt(0).select();
                break;
            case 1:
                mFloatingAddButton.setVisibility(View.VISIBLE);
                mTabLayout.getTabAt(1).select();
                break;
            default:
                mFloatingAddButton.setVisibility(View.INVISIBLE);
                mTabLayout.getTabAt(2).select();
                break;
        }
    }

    @Override
    public void onPageScrollStateChanged(int state) {

    }
}

How can I manage to tie everything together ?

Answer 1

In the method setupWithViewPager of class TabLayout, we can see that a callback is set on the view pager :

viewPager.addOnPageChangeListener(new TabLayoutOnPageChangeListener(this));

In the class TabLayoutOnPageChangeListener, here is the method onPageSelected :

public void onPageSelected(int position) {
final TabLayout tabLayout = mTabLayoutRef.get();
            if (tabLayout != null && tabLayout.getSelectedTabPosition() != position) {
                // Select the tab, only updating the indicator if we're not being dragged/settled
                // (since onPageScrolled will handle that).
                tabLayout.selectTab(tabLayout.getTabAt(position),
                        mScrollState == ViewPager.SCROLL_STATE_IDLE);
            }
        }

So here we can see that the tablayout should select the good tab when the viewpager changes its content.

Did you call setupWithViewPager right after setting the adapter of your ViewPager ?