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POViewPager re-instantiates items out of order after screen rotation
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copied!<p>I'm using a <code>ViewPager</code> that contains several ListViews, with code similar to that in the answer for <a href="https://stackoverflow.com/questions/7440012/infinite-viewpager">Infinite ViewPager</a>. The idea is to have something like the day view for the Google Calendar app (whose source seems to be unavailable; only the default calendar app's is but it uses a <code>ViewSwitcher</code>) - I want to make it seem like the user can swipe infinitely left and right, but there are actually only 3 items in the <code>ViewPager</code>, and when the user hits page 0 or 2, we set 1 as the current page and update accordingly.</p> <p>Now, this all works. However, strangely, when the phone is rotated and the activity is rebuilt (I'm avoiding using <code>configChanges</code> for now), the pages in the app are instantiated again, but out of order. Instead of 0->1->2, the order is 1->0->2, and this screws up the order of the pages in the app.</p> <p><strong>My Fragment, in <code>onActivityCreated()</code>:</strong></p> <pre><code>mPagerAdapter = new ContinuousPagerAdapter(R.layout.my_listview, this); // set the adapter mViewPager = (ViewPager) getView().findViewById(R.id.agendaViewPager); mViewPager.setOffscreenPageLimit(3); mViewPager.setOnPageChangeListener(this); mViewPager.setAdapter(mPagerAdapter); mViewPager.setSaveEnabled(false); // ... mViewPager.setCurrentItem(1, false); loadData(); </code></pre> <p><strong>The Pager Adapter:</strong></p> <pre><code>import android.content.Context; import android.os.Parcelable; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.util.Log; import android.view.LayoutInflater; import android.view.View; public class ContinuousPagerAdapter extends PagerAdapter { OnPageInstantiatedListener pListener; ViewPager container; int childLayoutResId; @SuppressWarnings("unused") private ContinuousPagerAdapter() { } /** * @param childLayoutResId Layout resource ID of the children to be inflated */ public ContinuousPagerAdapter(int childLayoutResId, OnPageInstantiatedListener pListener) { this.childLayoutResId = childLayoutResId; this.pListener = pListener; } @Override public int getCount() { return 3; } @Override public boolean isViewFromObject(View view, Object object) { return view == object; } @Override public Object instantiateItem(View container, int position) { this.container = (ViewPager) container; // inflate a new child view LayoutInflater li = (LayoutInflater) container.getContext().getSystemService( Context.LAYOUT_INFLATER_SERVICE); View childView = li.inflate(childLayoutResId, null, false); // add it to the view pager and return int count = this.container.getChildCount(); int actualPos = count > position ? position : count; this.container.addView(childView, actualPos); pListener.onPageInstantiated(actualPos); // sometimes use 0 instead of actualPos, with different but still inconsistent results return childView; } @Override public void destroyItem(View container, int position, Object object) { ((ViewPager) container).removeViewAt(position); } public static interface OnPageInstantiatedListener { public void onPageInstantiated(int position); } /** * Needed to ensure all the items are instantiated */ @Override public int getItemPosition(Object object) { return POSITION_NONE; } @Override public Parcelable saveState() { return null; } @Override public void restoreState(Parcelable state, ClassLoader loader) { } @Override public void finishUpdate(View container) { } } </code></pre> <p>I don't understand why the pages are instantiated in the 1->0->2 order after rotation. I'm not saving state either. Any insights into this would be helpful.</p>

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