Replace Fragment inside a ViewPager

Question

I\'m trying to use Fragment with a ViewPager using the FragmentPagerAdapter. What I\'m looking for to achieve is to replace a fragment, positioned

Answer 1

I found simple solution, which works fine even if you want add new fragments in the middle or replace current fragment. In my solution you should override getItemId() which should return unique id for each fragment. Not position as by default.

There is it:

public class DynamicPagerAdapter extends FragmentPagerAdapter {

private ArrayList mPages = new ArrayList();
private ArrayList mFragments = new ArrayList();

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

public void replacePage(int position, Page page) {
    mPages.set(position, page);
    notifyDataSetChanged();
}

public void setPages(ArrayList pages) {
    mPages = pages;
    notifyDataSetChanged();
}

@Override
public Fragment getItem(int position) {
    if (mPages.get(position).mPageType == PageType.FIRST) {
        return FirstFragment.newInstance(mPages.get(position));
    } else {
        return SecondFragment.newInstance(mPages.get(position));
    }
}

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

@Override
public long getItemId(int position) {
    // return unique id
    return mPages.get(position).getId();
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
    Fragment fragment = (Fragment) super.instantiateItem(container, position);
    while (mFragments.size() <= position) {
        mFragments.add(null);
    }
    mFragments.set(position, fragment);
    return fragment;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    super.destroyItem(container, position, object);
    mFragments.set(position, null);
}

@Override
public int getItemPosition(Object object) {
    PagerFragment pagerFragment = (PagerFragment) object;
    Page page = pagerFragment.getPage();
    int position = mFragments.indexOf(pagerFragment);
    if (page.equals(mPages.get(position))) {
        return POSITION_UNCHANGED;
    } else {
        return POSITION_NONE;
    }
}
}

Notice: In this example FirstFragment and SecondFragment extends abstract class PageFragment, which has method getPage().