Android: Changing fragments with ViewPager

Question

I'm using PagerSlidingTabStrip library for ViewPager https://github.com/astuetz/PagerSlidingTabStrip. I want to change the fragments while scrolling. I achieved that with the below code.

MainActivity.java

public class MainActivity extends SherlockFragmentActivity {

private MyPagerAdapter adapter;
ViewPager pager;
private PagerSlidingTabStrip tabs;

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

    tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
    pager = (ViewPager) findViewById(R.id.pager);
    adapter = new MyPagerAdapter(getSupportFragmentManager());

    pager.setAdapter(adapter);

    final int pageMargin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 4, getResources()
            .getDisplayMetrics());
    pager.setPageMargin(pageMargin);

    tabs.setViewPager(pager);

}

public class MyPagerAdapter extends FragmentPagerAdapter {
    private final String[] TITLES = {"First","Second","Third"};
    private SherlockFragment[] fragments = new SherlockFragment[] { new FirstFragment(), new SecondFragment(), new ThirdFragment()};

    public MyPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return TITLES[position];
    }

    @Override
    public int getCount() {
        return TITLES.length;
    }

    @Override
    public Fragment getItem(int position) {
        return fragments[position];
    }

}
}

FirstFragment.java

public class FirstFragment extends SherlockFragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    final View v = inflater.inflate(R.layout.fragment_main, container, false);
    Toast.makeText(getSherlockActivity(), "This is from first", Toast.LENGTH_SHORT).show();
    return v;
}
}

SecondFragment.java

public class SecondFragment extends SherlockFragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    final View v = inflater.inflate(R.layout.fragment_main, container, false);
    Toast.makeText(getSherlockActivity(), "SecondFragment", Toast.LENGTH_SHORT).show();
    return v;
}
}

ThirdFragment.java

public class ThirdFragment extends SherlockFragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    final View v = inflater.inflate(R.layout.fragment_main, container, false);
    Toast.makeText(getSherlockActivity(), "ThirdFragment", Toast.LENGTH_SHORT).show();
    return v;
}
}

I got the three fragments and I'm testing them with Toasts.

When the application opens with the MainActivity, FirstFragment is attached to the Activity , but it shows two toasts, one from Firstragment and other from SecondFragment , and when I scroll to second tab, it shows the toast of ThirdFragment.

So, I figured its going like this. If I scroll from left to right , the fragment right to the current fragment is displayed and if I scroll from right to left, the fragment left to the current fragment is displayed. Please help.

Thanks.

Answer 1

It's because of fragments caching. When you visit some fragments, sibling fragments to it also being created (onCreate() called).