CODEWITHSUNDEEP
javaandroidandroid-viewpager
Yuri Misyac
Yuri Misyac

Reputation: 4909

Update fragment on view pager when they stand visible to user

I have 50 pages and need to constantly update the current fragment, ChangeListener work fine but first refresh don't work, how to implement a fragment refresh when it becomes visible to the user ?

MyPagerAdapter adapter = new MyPagerAdapter(getChildFragmentManager(), data);
mViewPager.setAdapter(adapter);
int position = data.size() - 1;
adapter.getFragment(position).refresh();
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}

    @Override
    public void onPageSelected(int position) {
        adapter.getFragment(position).refresh();
    }

    @Override
    public void onPageScrollStateChanged(int state) {}
});

PageAdapter

private class MyPagerAdapter extends FragmentStatePagerAdapter {

    private final List<DateTime> mData;
    private Map<Integer, PagerFragment> mMap = new HashMap<>();

    public MyPagerAdapter(FragmentManager fm, List<DateTime> data) {
        super(fm);
        mData = data;
    }

    @Override
    public Fragment getItem(int position) {
        return PagerFragment.newInstance(mData.get(position));
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        PagerFragment f = (PagerFragment) super.instantiateItem(container, position);
        mMap.put(position, f);
        return f;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        super.destroyItem(container, position, object);
        mMap.remove(position);
    }

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

    public PagerFragment getFragment(int position) {
        return mMap.get(position);
    }
}

Upvotes: 1

Views: 93

Answers (1)

Yuri Misyac
Yuri Misyac

Reputation: 4909

The first ask is not correct, I needed "Update fragment when they stand visible to user on view pager" and I found an answer:

Edit:

public abstract class PageFragment extends Fragment {

protected Boolean mVisibleToUserFlag = null;

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

    if (mVisibleToUserFlag != null && mVisibleToUserFlag) {
        onVisible();
    }
}

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);

    if (isVisibleToUser && (mVisibleToUserFlag == null || mVisibleToUserFlag == false)) {
        mVisibleToUserFlag = true;
        if (isResumed()) {
            onVisible();
        }
    } else if (!isVisibleToUser && mVisibleToUserFlag == null) {
        mVisibleToUserFlag = false;
    } else if (!isVisibleToUser && mVisibleToUserFlag) {
        onHide();
        mVisibleToUserFlag = false;
    }
}

@Override
public void onDestroyView() {
    super.onDestroyView();

    mVisibleToUserFlag = null;
}

/**
 * This method invoked when page stand visible to user.
 */
public abstract void onVisible();

/**
 * This method invoked then page change state visibility change to hidden.
 */
public abstract void onHide();

}

Upvotes: 1

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