Question

I’m trying to build a viewpager for the first time. I’m populating an ArrayList of views in the main onCreate method and passing it to the constructor of the PagerAdapter. The activity launches fine and I can see the ViewPager (or at least its background) but none of the views appear in it, I just see the blank background. I’ve tried inflating layout XMLs that I know are working in other widgets, so it can’t be a problem there. I’m guessing it has something to do with the way I have the instantiateObject method written. Anyway, here is my adapter:

    public class StoryAdapter extends PagerAdapter {
    private Context ctx;
    private ViewBuilder viewBuilder;

    public StoryAdapter(Context ctx, ArrayList<View> views){
        this.ctx = ctx;
    }


    @Override
    public int getCount() {         
        return views.size();
    }

    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public Object instantiateItem(View arg0, int arg1) {
            View v = views.get(arg1);
            ((ViewPager) arg0).addView(v);
            return v;
            }

    @Override
    public void destroyItem(View pager, int arg1, Object view) {
    ((ViewPager) pager).removeView((View) view);

}
}

and here is my onCreate():

public class ShowStory extends Activity {
public int totalPages;
Button backBtn;
public String text;
public ArrayList<View> views;

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

    backBtn = (Button)findViewById(R.id.backBtn);

    backBtn.setOnClickListener(new OnClickListener() {
        public void onClick(View view){
            Intent intent = new Intent();
            setResult(RESULT_CANCELED, intent);        
            finish();       
        }
    });
    ViewPager vp = (ViewPager)findViewById(R.id.storyFlipper);
    views = new ArrayList<View>();

    View v0 = getLayoutInflater().inflate(R.layout.galleryview, null);

    TextView v0t = (TextView)v0.findViewById(R.id.headline);
    v0t.setText("COVER1");

    View v1 = getLayoutInflater().inflate(R.layout.coverpage, null);
//      TextView v1t = (TextView)findViewById(R.id.coverText);
//      v1t.setText("COVER2");      

    View v2 = getLayoutInflater().inflate(R.layout.coverpage, null);
//      TextView v2t = (TextView)findViewById(R.id.coverText);
//      v2t.setText("COVER3");  

views.add(v0);
views.add(v1);
views.add(v2);  


    StoryAdapter sa = new StoryAdapter(this, views);        
    vp.setAdapter(sa);

PS I’m doing this mainly for educational purposes, this is obviously a very simple example. Any help will be greatly appreciated!

——Edit: I tried what you suggested:

        @Override
    public Object instantiateItem(View collection, int position) {
    LayoutInflater inflater = (LayoutInflater) collection.getContext()
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    int resId = 0;
    switch (position) {

    case 0:
        resId = R.layout.coverpage;
        break;
    case 1:
        resId = R.layout.coverpage;
        break;
    case 2:
        resId = R.layout.coverpage;
        break;
    case 3:
        resId = R.layout.coverpage;
        break;

    }
    View view = inflater.inflate(resId, null);
    ((ViewPager) collection).addView(view, 0);
    return view;

    }

and have the same result – I see the blank background of the viewpager, but no views appear

Answer 1

I figured it out – it was because I didn’t have anything in the isViewFromObject method. Replacing null with

return arg0 == (View) arg1;

solved the problem.