open activity on specific tab selected

Question

I want to implement Tablayout addOnTabSelectedListener to open a new Activity on a certain tab click. There are 3 tabs and at present they are connected with fragments. I want to start an activity when I click position 1 tab. I can do that in onTabSelected but before opening activity it shows the fragment attached to that same position. How to remove that fragment?

public class MainActivity extends AppCompatActivity {

    private TabLayout tabs;
    private ViewPager viewpager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        tabs = (TabLayout)findViewById(R.id.tabs);
        viewpager = (ViewPager)findViewById(R.id.viewpager);
        setupViewPager(viewpager);


        tabs.addTab(tabs.newTab());
        tabs.addTab(tabs.newTab());
        tabs.addTab(tabs.newTab());

        tabs.setupWithViewPager(viewpager);

        tabs.addOnTabSelectedListener(onTabSelectedListener(viewpager));

    }

    private TabLayout.OnTabSelectedListener onTabSelectedListener(final ViewPager viewPager) {

        return new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

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

            }
        };
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new Frag1(), "ONE");
        adapter.addFragment(new Frag2(), "TWO");
        adapter.addFragment(new Frag3(), "THREE");
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabs));
        onTabSelectedListener(viewPager);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }


        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
}


    private TabLayout.OnTabSelectedListener onTabSelectedListener(final ViewPager viewPager) {

        return new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

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

            }
        };
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new Frag1(), "ONE");
        adapter.addFragment(new Frag2(), "TWO");
        adapter.addFragment(new Frag3(), "THREE");
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabs));
        onTabSelectedListener(viewPager);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }


        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }

}

Answer 1

try this:

use a FragmentStatePagerAdapter instead the reason for this is that the FragmentPagerAdapter will keep all the views that it loads into memory forever. Where the FragmentStatePagerAdapter disposes of views that fall outside the current

Also Override the adapter method getItemPosition

For example:

    private class ViewPagerAdapter extends FragmentStatePagerAdapter {

    //... your existing code

    @Override
    public int getItemPosition(Object object){
        return PagerAdapter.POSITION_NONE;
    }

}

source

it will recreate your fragment each time instead of loading them from memory first..

To start activity do it in your particular fragment's onCreate()

Hope this helps..

Answer 2

I had same requirement, what i did is overlap textview on center of TabLayout using RelativeLayout & apply click event on textview. I can not post my layout please refer demo image