Change image on Tab in TabLayout when Selected

Question

I am using Design TabLayout,

Answer 1

add the setOnTabSelectedListener to the tabLayout object

i named mine navigation

navigation.setOnTabSelectedListener(
            new TabLayout.ViewPagerOnTabSelectedListener(mainView) {

                @Override
                public void onTabSelected(TabLayout.Tab tab) {
                    super.onTabSelected(tab);

                    // 1. get the custom View you've added
                    View tabView = tab.getCustomView();

                    // get inflated children Views the icon and the label by their id
                    TextView tab_label = (TextView) tabView.findViewById(R.id.nav_label);
                    ImageView tab_icon = (ImageView) tabView.findViewById(R.id.nav_icon);

                    // change the label color, by getting the color resource value
                    tab_label.setTextColor(getResources().getColor(R.color.active_color));
                    // change the image Resource
                    // i defined all icons in an array ordered in order of tabs appearances
                    // call tab.getPosition() to get active tab index.
                    tab_icon.setImageResource(navIconsActive[tab.getPosition()]);
                }

                // do as the above the opposite way to reset tab when state is changed 
                // as it not the active one any more
                @Override
                public void onTabUnselected(TabLayout.Tab tab) {
                    super.onTabUnselected(tab);
                    View tabView = tab.getCustomView();
                    TextView tab_label = (TextView) tabView.findViewById(R.id.nav_label);
                    ImageView tab_icon = (ImageView) tabView.findViewById(R.id.nav_icon);

                    // back to the black color
                    tab_label.setTextColor(getResources().getColor(R.color.dark_grey));
                    // and the icon resouce to the old black image 
                    // also via array that holds the icon resources in order 
                    // and get the one of this tab's position
                    tab_icon.setImageResource(navIcons[tab.getPosition()]);
                }

                @Override
                public void onTabReselected(TabLayout.Tab tab) {
                    super.onTabReselected(tab);
                }
            }
    );

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that will do the job perfectly , and you can pad yourself in the back as i did myself :D