cwac-pager | CWAC-Pager : Power to the PagerAdapter | Android library

public class MainActivity extends AppCompatActivity implements TabLayout.OnTabSelectedListener {

    private ViewPager viewPager;
    private ArrayPagerAdapter pagerAdapter;
    private TabLayout tabLayout;

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

        setSupportActionBar((Toolbar) findViewById(R.id.app_toolbar));

        tabLayout = findViewById(R.id.tab_layout);
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        viewPager = findViewById(R.id.pager);
        pagerAdapter = new CustomPagerAdapter(getSupportFragmentManager(), new ArrayList<PageDescriptor>());
        viewPager.setAdapter(pagerAdapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.addOnTabSelectedListener(this);
    }

    @Override
    public void onStart() {
        super.onStart();
        pagerAdapter.add(new TestPageDescriptor());
        tabLayout.addTab(tabLayout.newTab().setText("Hello"));
        // Uncomment the following lines to make the app crash
        pagerAdapter.add(new TestPageDescriptor()); // CRASH
        tabLayout.addTab(tabLayout.newTab().setText("Hello2"));
    }

    @Override
    public void onStop() {
        super.onStop();
        // Remove all the tabs (required in my main application, not in this test)
        tabLayout.removeAllTabs();
        for (int i = 0; i < pagerAdapter.getCount(); i++) {
            pagerAdapter.remove(i);
        }
    }

    @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 class CustomPagerAdapter extends ArrayPagerAdapter<Fragment> {

        CustomPagerAdapter(FragmentManager fragmentManager, List<PageDescriptor> descriptors) {
            super(fragmentManager, descriptors);
        }

        @Override
        protected Fragment createFragment(PageDescriptor desc) {
            return new TestFragment();
        }
    }

    private class TestPageDescriptor extends SimplePageDescriptor {

        TestPageDescriptor() {
            super("Test","TestHey");
        }
    }
}

public class TestFragment extends Fragment {

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.test_frag, container, false);
    }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="me.test.myapplication.MainActivity"
    android:orientation="vertical">

    <android.support.v7.widget.Toolbar
        android:id="@+id/app_toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        app:title="@string/app_name" />

    <android.support.design.widget.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        android:elevation="4dp"
        android:minHeight="?attr/actionBarSize"/>

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

I/Process: Sending signal. PID: 3877 SIG: 9
Application terminated.