ViewPager does not respond to tab upon clicking

Question

I tried to add a tab with a fragment in my activity but it does not respond or event display.

Here is my code below.

This is my MAIN ACTIVITY:

private void setupTabLayout() {
    TabLayout tabLayout = findViewById(R.id.tab_layout);
    tabLayout.addTab(tabLayout.newTab().setText("COMMENTS"));
    tabLayout.addTab(tabLayout.newTab().setText("ATTACHMENTS"));
    tabLayout.addTab(tabLayout.newTab().setText("AUDIT TRAIL"));
    tabLayout.addTab(tabLayout.newTab().setText("APPROVERS"));

    final ViewPager viewPager = findViewById(R.id.pager);
    final PagerAdapter adapter = new com.example.android.ontrack.adapters.PagerAdapter(getSupportFragmentManager(),tabLayout.getTabCount());
    viewPager.setAdapter(adapter);
    viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
    tabLayout.addOnTabSelectedListener(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) {

        }
    });
}



Here is my XML code:

 <android.support.v4.widget.NestedScrollView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginBottom="@dimen/margin"
                android:fillViewport="true">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <android.support.design.widget.TabLayout
                    android:id="@+id/tab_layout"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginBottom="@dimen/margin"
                    android:paddingLeft="@dimen/padding"
                    android:paddingRight="@dimen/padding"
                    android:background="@color/blue"
                    android:fillViewport="true"
                    app:tabMode="scrollable"
                    app:tabIndicatorColor="@android:color/white"
                    app:tabSelectedTextColor="@android:color/white"
                    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

                    <android.support.v4.view.ViewPager
                        android:id="@+id/pager"
                        android:layout_width="match_parent"
                        android:layout_height="match_parent" />

            </RelativeLayout>

            </android.support.v4.widget.NestedScrollView>

And this is my PagerAdapter:

public class PagerAdapter extends  FragmentStatePagerAdapter {
    int mNumOfTabs;

    public PagerAdapter(FragmentManager fm, int mNumOfTabs) {
        super(fm);
        this.mNumOfTabs = mNumOfTabs;
    }

    @Override
    public Fragment getItem(int position) {

        switch (position) {
            case 0:
                CommentsFragment tab1 =  new CommentsFragment();
                return tab1;
            case 1:
                AttachmentsFragment tab2 = new AttachmentsFragment();
                return tab2;
            case 2:
                AuditTrailFragment tab3 = new AuditTrailFragment();
                return tab3;
            case 3:
                ApproversFragment tab4 = new ApproversFragment();
                return tab4;
            default:
                return null;
        }
    }

    @Override
    public int getCount() {
        return mNumOfTabs;
    }
}

Please read [Under what circumstances may I add “urgent” or other similar phrases to my question, in order to obtain faster answers?](//meta.stackoverflow.com/q/326569) - the summary is that this is not an ideal way to address volunteers, and is probably counterproductive to obtaining answers. Please refrain from adding this to your questions. — halfer, Feb 11 '18 at 13:14
You have [two answers here](https://stackoverflow.com/a/48601167) and [one here](https://stackoverflow.com/a/48605933) that you have forgotten to reply to. Voting, acceptance and commenting are not mandatory on the Stack Overflow platform, but if you develop a reputation for someone who takes help without any response at all, people may stop helping you. — halfer, Feb 11 '18 at 13:18

Pavneet_Singh · Answer 1 · 2018-02-11T14:18:58.223

3

From Docs

You just need to call tabLayout.setupWithViewPager(viewPager);

and seems like there is an issue in XML, you TabLayout should be inside ViewPager

because

viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

mean you want to change the tab and every tab is hosting a fragment.

Update : You have removed the code to add tabs, as shown in the github link, posted in comments.

// add these lines again
TabLayout tabLayout = findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("COMMENTS"));
tabLayout.addTab(tabLayout.newTab().setText("ATTACHMENTS"));
tabLayout.addTab(tabLayout.newTab().setText("AUDIT TRAIL"));
tabLayout.addTab(tabLayout.newTab().setText("APPROVERS"));
ViewPager viewPager = (ViewPager)findViewById(R.id.viewPager);
viewPager.setAdapter(new CustomFragmentPagerAdapter(getSupportFragmentManager()));
viewPager.setCurrentItem(2);
tabLayout.setupWithViewPager(viewPager);
//... code of listener etc

edited Feb 11 '18 at 14:18

answered Feb 11 '18 at 13:32

Pavneet_Singh

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It does not work. my tab names are gone. tabLayout.setupWithViewPager(viewPager); viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout)); tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() – niel Feb 11 '18 at 13:38
have you changed the xml? – Pavneet_Singh Feb 11 '18 at 13:39
you tablyout should be inside viewpager ,[look here for example](https://developer.android.com/reference/android/support/design/widget/TabLayout.html) – Pavneet_Singh Feb 11 '18 at 13:42
@niel seems like XML layout issue , try changing `android:layout_width="wrap_content"` to `android:layout_width="match_parent"` in tablayout – Pavneet_Singh Feb 11 '18 at 13:56
my tabs are still gone. – niel Feb 11 '18 at 14:01
Here's a sample of mine for this. It should work. https://github.com/ElifBon/FragmentAdapterProject – quick release Feb 11 '18 at 14:06
you removed the code of adding tab by mistake , try update – Pavneet_Singh Feb 11 '18 at 14:09
tabLayout.setupWithViewPager(viewPager); - I removed that code then it shows now but still my pager does not. – niel Feb 11 '18 at 14:43

score 1 · Answer 2 · answered Feb 11 '18 at 14:17

Here's sample of mine for this. It should work. https://github.com/ElifBon/FragmentAdapterProject

xml:

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <android.support.design.widget.TabLayout
        android:id="@+id/tabLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"></ViewPager>
</LinearLayout>

Your activity:

 TabLayout tabLayout = (TabLayout)findViewById(R.id.tabLayout);
 ViewPager viewPager = (ViewPager)findViewById(R.id.viewPager);
 viewPager.setAdapter(new CustomFragmentPagerAdapter(getSupportFragmentManager()));
 viewPager.setCurrentItem(2);
 tabLayout.setupWithViewPager(viewPager);

 tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
     @Override
     public void onTabSelected(TabLayout.Tab tab) {
         // TODO : Something
     }

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

     }

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

     }
 });

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

    }

    @Override
    public void onPageSelected(int position) {
        // TODO : Something
    }

    @Override
    public void onPageScrollStateChanged(int state) {

    }
});

Adapter:

private class CustomFragmentPagerAdapter extends FragmentPagerAdapter{

Fragment1 fragment1;
Fragment2 fragment2;
Fragment3 fragment3;

    public  CustomFragmentPagerAdapter(android.support.v4.app.FragmentManager fm){
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        if(position == 0){
            if(fragment1 == null){
                fragment1 = Fragment1.getInstance();
            }
            return  fragment1;
        }else if(position == 1){
            if(fragment2 == null){
                fragment2 = Fragment2.getInstance();
            }
            return fragment2;
        }else if(position == 2){
            if(fragment3 == null){
                fragment3 = Fragment3.getInstance();
            }
            return fragment3;
        }else{
            return null;
        }
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return "Title - " + String.valueOf(position);
    }

    @Override
    public int getCount() {
        return 3;
    }
}

ViewPager does not respond to tab upon clicking

2 Answers2