Delete a Fragment from ViewPager

Question

I have a ViewPager, and there's a button when clicked, deletes the current fragment from the PagerAdapter, and prevents the user from swiping there. I researched and found this Remove Fragment Page from ViewPager in Android to be the closest to what I want.

In my fragment to be deleted:

       @Override
        public void onClick(View v) {
            db.delete(count); //SqliteDatabase deletion
            displayActivity.removeCurrentFragment(0);
        }

My PagerAdapter
    public class PagerAdapter extends FragmentPagerAdapter {

long baseId = 0;
public static List<Fragment> fragmentArrayList = new ArrayList<Fragment>();

public PagerAdapter(FragmentManager fm){
    super(fm);
    fragmentArrayList.add(new FragmentOne());
    fragmentArrayList.add(new FragmentTwo());
    fragmentArrayList.add(new FragmentThree());
}
@Override
public Fragment getItem(int position) {
    return fragmentArrayList.get(position);
    }

}

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

@Override
public int getItemPosition(Object object){
    return PagerAdapter.POSITION_NONE;
}
@Override
public long getItemId(int position) {
    // give an ID different from position when position has been changed
    return baseId + position;
}

}

This is the activity (DisplayActivity) that hosts the pagerAdapter

public class DisplayActivity extends AppCompatActivity {

ViewPager viewPager;
PagerAdapter pagerAdapter;



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

    viewPager = (ViewPager) findViewById(R.id.pager);

    PagerAdapter pagerAdapter = new PagerAdapter(getSupportFragmentManager());
    viewPager.setAdapter(pagerAdapter);

}

public void removeCurrentFragment(int position){
    pagerAdapter.fragmentArrayList.remove(position);
    pagerAdapter.notifyDataSetChanged();
}

What did I do wrong here?

I'm getting an error of

 .removeCurrentFragment(int)' on a null object reference

So this error suggests that my method call removeCurrentFragment is referencing a null object, how do I fix it?

You should take a look at [this answer](http://stackoverflow.com/a/26944013/5287436) — Hai nguyen thanh, Nov 08 '16 at 01:29

score 0 · Answer 1 · answered Feb 21 '16 at 08:02

0

You have used

    PagerAdapter pagerAdapter = new PagerAdapter(getSupportFragmentManager());

so you are creating a new local variable instead of using your global variable. Instead change your line as

     pagerAdapter = new PagerAdapter(getSupportFragmentManager());

It should work.

answered Feb 21 '16 at 08:02

Ragesh Ramesh

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That makes sense, however, after changing I'm still getting the same error. – Jasmine Rain Feb 21 '16 at 15:15
Please paste your log – Ragesh Ramesh Feb 21 '16 at 17:22
java.lang.NullPointerException: Attempt to invoke virtual method 'void .DisplayActivity.removeCurrentFragment(int)' on a null object reference – Jasmine Rain Feb 21 '16 at 17:30

score 0 · Answer 2 · answered Feb 21 '16 at 08:07

Your onCreate method should look like this.

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

    viewPager = (ViewPager) findViewById(R.id.pager);

    pagerAdapter = new PagerAdapter(getSupportFragmentManager());
    viewPager.setAdapter(pagerAdapter);

}

Delete a Fragment from ViewPager

2 Answers2