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How to Remove Fragment from FragmentPagerAdapter?

I know there are some topics about this here already but I could not find a solution which I could get to work for my case.

I have a working sliding gallery using a custom FragmentActivity and FragmentPagerAdapter which holds a list of Fragments.

FragmentActivity

FragmentPagerAdapter

Within the FragmentActivity is a ImageView "delete". If clicked, the function deleteMedia() is called which then should remove the current Fragment and the following Fragment should be displayed.
How would I have to do that in my example?

FragmentActivity

ImageView

deleteMedia()

Fragment

Fragment

FragmentActivity:

public class GalleryPagerActivity extends FragmentActivity implements OnClickListener {

private Intent intent;
private SharedPreferences settings;
private PagerAdapter mPagerAdapter;
private ViewPager mPager;
private List<Fragment> fragments;
private List<WhiteboardMedia> wiList;

private int selectedPosition;
private LinearLayout llTop;
private TextView tvTop;
private ImageView delete;
private ImageView share;
private TextView tvCounter;
private TextView tvFilename;
private TextView tvFilesize;
private TextView tvDate;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

try {
super.setContentView(R.layout.gallery_pager);

intent = getIntent();

Type collectionType = new TypeToken<List<WhiteboardMedia>>(){}.getType();

wiList = gson.fromJson(intent.getStringExtra("wiList"), collectionType);
selectedPosition = intent.getIntExtra("position", 1);

llTop = (LinearLayout) findViewById(R.id.llTop);
llTop.setOnClickListener(this);
tvTop = (TextView) findViewById(R.id.tvTop);
tvTop.setOnClickListener(this);
delete = (ImageView) findViewById(R.id.imgDelete);
delete.setOnClickListener(this);
share = (ImageView) findViewById(R.id.imgShare);
share.setOnClickListener(this);

tvCounter = (TextView) findViewById(R.id.tvCounter);
tvFilename = (TextView) findViewById(R.id.tvFilename);
tvFilesize = (TextView) findViewById(R.id.tvFilesize);
tvDate = (TextView) findViewById(R.id.tvDate);

createContextMenu();
initDropbox();
} catch (Exception e) {
Log.e("GalleryPagerActivity", e.getLocalizedMessage());
}
}

/**
* Initialise the pager
*/
private void initialisePager() {
mPager = (ViewPager) super.findViewById(R.id.viewpager);
mPager.setAdapter(this.mPagerAdapter);
mPager.setOnPageChangeListener(new GalleryPageListener(tvCounter, tvFilename, tvFilesize, tvDate, wiList));

mPager.setCurrentItem(selectedPosition, true);
updatePage(selectedPosition);
}

public void updatePage(int position)
{
int focusedPage = position + 1;
Log.i("onPageSelected", "page selected " + position);

WhiteboardMedia wiImage = wiList.get(position);

String imageDate = "N/A";
try {
Date dateTaken= new Date(); //wiImage.getDate();
SimpleDateFormat sdf = new SimpleDateFormat("yy/MM/dd");
imageDate = sdf.format(dateTaken);
} catch (Exception e) {
}

try {
tvCounter.setText(focusedPage + "/" + wiList.size());
tvFilename.setText(wiImage.getFilename());
tvFilesize.setText(wiImage.getSize() + "a");
tvDate.setText(imageDate);
} catch (Exception e) {
}
}

@Override
protected void onResume() {
super.onResume();
}

@Override
public void onDestroy() {
super.onDestroy();
}

private WhiteboardMedia getActiveWhiteboardImage() {
return wiList.get(mPager.getCurrentItem());
}

private final int DELETE = 1;

@Override
public boolean onCreateOptionsMenu(Menu menu) {
menu.add(1, DELETE, 2, R.string.delete).setIcon(R.drawable.menu_btn_trash);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case DELETE:
deleteMedia();
return true;
}
return super.onContextItemSelected(item);
}

@Override
public void onClick(View v) {
if (v == delete) {
deleteMedia();
}
}

private void deleteMedia() {
// TODO delete the active Fragment and display the next Fragment in the list
}

/******************************************************************************
* Context Menu
*****************************************************************************/
private void createContextMenu() {
// context menu stuff
}

@Override
protected Dialog onCreateDialog(int id) {
// stuff
}

}


FragmentPagerAdapter:

public class GalleryPagerAdapter extends FragmentPagerAdapter {

private final List<Fragment> fragments;

public GalleryPagerAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments = fragments;
}

@Override
public Fragment getItem(int position) {
return this.fragments.get(position);
}

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


Thanks for help!

5 Answers
5

First, I suggest that you consider altering your FragmentPagerAdapter, to look more like the sample. You normally do not hold a list of fragments, any more than an ArrayAdapter normally holds a list of Views for the rows. Normally, you create the fragments on demand, and somebody else holds the list.

FragmentPagerAdapter

ArrayAdapter

Views

Then, to delete something, delete it from your model data (what the FragmentPagerAdapter normally wraps). Make sure that getCount() will then return the right number of items. Then, call notifyDataSetChanged() on the FragmentPagerAdapter, which should trigger a redraw of the ViewPager.

FragmentPagerAdapter

getCount()

notifyDataSetChanged()

FragmentPagerAdapter

ViewPager

for (int i = 0; i < wiList.size(); i++) { WhiteboardMedia tmpWi = wiList.get(i); if (tmpWi.getType() == IMAGE) { fragments.add(IMAGE); } else if () { fragments.add(AUDIO); } else if () { fragments.add(VIDEO); } } mAdapter = new MPagerAdapter(getSupportFragmentManager(), fragments);

getItem()

ArrayPagerAdapter

FragmentPagerAdapter

FragmentStatePager

FragmentPagerAdapter

that is the solution I'm using:

mViewPager : is the view you are using to set you Fragment

mViewPager = (YourViewPager) findViewById(R.id.myPager);


TABLE : is just a Integer list of the position of all my Fragments

public void destroyAllItem() {
int mPosition = mViewPager.getCurrentItem();
int mPositionMax = mViewPager.getCurrentItem()+1;
if (TABLE.size() > 0 && mPosition < TABLE.size()) {
if (mPosition > 0) {
mPosition--;
}

for (int i = mPosition; i < mPositionMax; i++) {
try {
Object objectobject = this.instantiateItem(mViewPager, TABLE.get(i).intValue());
if (objectobject != null)
destroyItem(mViewPager, TABLE.get(i).intValue(), objectobject);
} catch (Exception e) {
Log.i(TAG, "no more Fragment in FragmentPagerAdapter");
}
}
}
}

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

if (position <= getCount()) {
FragmentManager manager = ((Fragment) object).getFragmentManager();
FragmentTransaction trans = manager.beginTransaction();
trans.remove((Fragment) object);
trans.commit();
}
}


I found a solution ovverriding the method "onPostResume()" of the activity and calling the notifyDataSetChanged inside that.

@Override
protected void onPostResume() {
super.onPostResume();
if(this.mCustomPagerAdapter!=null){
this.mCustomPagerAdapter.notifyDataSetChanged();
}
}


If you are using FragmentPagerAdapter for adding and removing fragments at random position(not always at the end) dynamically, there is a method you need to taken more attention which is getItemId. By default, FragmentPagerAdapter uses position combines viewId as the tag name for fragments, however the position changes if you add or remove fragments. As a result, you may get an empty page because the position you are adding is occupied by an existing fragment. To solved this problem, override getItemId.

@Override
public long getItemId(int position) {
long itemId = ...; //Provide your unique ID here according to you logic
return itemId;
}


In my case, when i try to remove one item from the adapter, i will do as follow:

// get the position of item to remove
int position = getBinding().vp.getCurrentItem();
// remove the item from adapter
adapter.removeItem(position);
adapter.notifyDataSetChanged();
// minus one from the count
totalInvoice--;
updateTitle(getBinding().vp.getCurrentItem());
if (totalInvoice == 0) {
finish();
}
// set the adapter to view pager again
getBinding().vp.setAdapter(adapter);
// smooth scroll to given position
getBinding().vp.setCurrentItem(position);


The reason that i did above is that i find that even though you removed one from the data list, but the view of fragment still exist. So you have to let the view pager instantiate the view of given position. The answer above which trying to remove all fragments doesn't work for me. So, I find out the poor way of setting adapter to view pager again.

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