IssueTracker

If you create a ViewPager and add an OnPageChangeLsitener you might expect the listener to be called whenever a (new) page is displayed - even for page 0 straight after creation. However it isn't.

Use case: I have an activity that has a five page ViewPager.
In the onResume() method of that activity, I check for an intent parameter specifying which page to display and call pager.setCurrentItem(n, false) to select that page.

The ViewPager also has an OnPageChangeListener to watch for page changes and will tweak the page content (it highlights a field on the page).

The trouble is, if we have just created the ViewPager, and if the page selected is page 0, the OnPageChangeListener won't be called.  Obviously this is because the ViewPager defaults to page 0 and doesn't think the page has changed.

IMO the listener ought to be called immediately after creation (with page set to 0).

At the moment, the work around is that I have to check which page is currently displayed and call the listener myself if necessary.


public class FooActivity extends Activity
{
   @Override
   public void onCreate(Bundle savedInstanceState)
   {
      super.onCreate(savedInstanceState);

      setContentView(R.layout.view_pager);

      ViewPager  pager = (ViewPager) findViewById(R.id.view_pager);
      pager.setAdapter(new FooPagerAdapter(this));

      pager.setOnPageChangeListener(new OnPageChangeListener() {
         
         @Override
         public void onPageSelected(int position)
         {
/**/Log.d("foo", "**** onPageSelected = "+position);
         }

         @Override
         public void onPageScrolled(int arg0, float arg1, int arg2) {}
         @Override
         public void onPageScrollStateChanged(int arg0) {}
      });
   }


   @Override
   protected void  onResume()
   {
      super.onResume();

      int page = getIntent().getIntExtra("page", 0))
      ViewPager  pager = (ViewPager) findViewById(R.id.view_pager);
      pager.setCurrentItem(page, false);
   }

}


Android: 4.03