Click event from Adapter to Activity or Fragment in Android

Question

I have customized expandable list view showing in Navigation Drawer. I have a click listener in Adapter I would like to send click event from adapter to my activity or fragment.

Is this possible if so how do I go about doing it?

Here is a snippet of my adapter:

public class CustomAdapter implements ExpandableListAdapter {

    @Override
    public View getGroupView(int position, boolean isExpanded, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.menu_item, parent, false);
        }

        TextView text = (TextView) convertView.findViewById(android.R.id.text1);
        text.setText(items.get(position).getName());
        ImageView imageView = (ImageView) convertView.findViewById(R.id.imageIndicator);

        if (items.get(position).isHasChild() && items.get(position).getSubMenuItems().size() > 0)
            imageView.setVisibility(View.VISIBLE);
        else
            imageView.setVisibility(View.INVISIBLE);

        if (isExpanded)
            imageView.setImageResource(R.drawable.down);
        else
            imageView.setImageResource(R.drawable.next);

        return convertView;
    }

    @Override
    public View getChildView(final int childPosition, int groupPosition, boolean isExpanded, View convertView, final ViewGroup parent) {

        View view = convertView;

        if (view == null) {
            view = inflater.inflate(R.layout.expandable_list, parent, false);
        }
        ExpandableHeightListView childList = (ExpandableHeightListView) view.findViewById(R.id.childList);
        childList.setAdapter(new CustomAdapter(context, items.get(childPosition).getSubMenuItems()));
        childList.invalidate();
        parent.invalidate();

        final ExpandableHeightListView list = childList;
        childList.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            int previousItem = -1;

            @Override
            public void onGroupExpand(int groupPosition) {
                ArrayList<eMenuItem> tempItems = items.get(childPosition).getSubMenuItems();

                if (tempItems.get(groupPosition).getSubMenuItems().size() == 0) {
                    Toast.makeText(context, "Start Activity", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(context, "Clicked on " + tempItems.get(groupPosition).getName(), Toast.LENGTH_SHORT).show();
                }

                if (groupPosition != previousItem)
                    list.collapseGroup(previousItem);

                previousItem = groupPosition;
                list.invalidate();
                parent.invalidate();
            }
        });
        return view;
    }
}

WITH HELP FROM Jared Burrows - How to create interface between Fragment and adapter?

Added few things to my CustomAdapter and FragmentActivity

public class CustomAdapter implements ExpandableListAdapter {

public CustomAdapter(MainActivity fragmentactivity) 
{
    try 
    {
        this.mAdapterCallback = ((AdapterCallback) fragmentactivity);
    } 
    catch (ClassCastException e) 
    {
        throw new ClassCastException("Fragment must implement AdapterCallback.");
    }
}

public static interface AdapterCallback 
{
    void onMethodCallback();
}

    @Override
    public View getGroupView(int position, boolean isExpanded, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.menu_item, parent, false);
        }

        TextView text = (TextView) convertView.findViewById(android.R.id.text1);
        text.setText(items.get(position).getName());
        ImageView imageView = (ImageView) convertView.findViewById(R.id.imageIndicator);

        if (items.get(position).isHasChild() && items.get(position).getSubMenuItems().size() > 0)
            imageView.setVisibility(View.VISIBLE);
        else
            imageView.setVisibility(View.INVISIBLE);

        if (isExpanded)
            imageView.setImageResource(R.drawable.down);
        else
            imageView.setImageResource(R.drawable.next);

        return convertView;
    }

    @Override
    public View getChildView(final int childPosition, int groupPosition, boolean isExpanded, View convertView, final ViewGroup parent) {

        View view = convertView;

        if (view == null) {
            view = inflater.inflate(R.layout.expandable_list, parent, false);
        }
        ExpandableHeightListView childList = (ExpandableHeightListView) view.findViewById(R.id.childList);
        childList.setAdapter(new CustomAdapter(context, items.get(childPosition).getSubMenuItems()));
        childList.invalidate();
        parent.invalidate();

        final ExpandableHeightListView list = childList;
        childList.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            int previousItem = -1;

            @Override
            public void onGroupExpand(int groupPosition) {
                ArrayList<eMenuItem> tempItems = items.get(childPosition).getSubMenuItems();

                if (tempItems.get(groupPosition).getSubMenuItems().size() == 0) {
                    Log.e("value","position"+childPosition);
                Log.e("value","position"+groupPosition);
                Log.e("value","position"+tempItems.get(groupPosition).getName());

                mAdapterCallback.onMethodCallback();

                } else {
                    Toast.makeText(context, "Clicked on " + tempItems.get(groupPosition).getName(), Toast.LENGTH_SHORT).show();
                }

                if (groupPosition != previousItem)
                    list.collapseGroup(previousItem);

                previousItem = groupPosition;
                list.invalidate();
                parent.invalidate();
            }
        });
        return view;
    }
}

AND IN MY MAIN ACTIVITY:

public class MainActivity extends FragmentActivity implements AdapterCallback
{
 @Override
  protected void onCreate(Bundle savedInstanceState)
  {
    this.mMyAdapter = new CustomAdapter(this);
   }

And then added this outside Oncreate:

public void onMethodCallback() 
{
        Log.e("Call","VALUE");
 }
 }

but I am getting the NPE Error still.. This is strange when I don't use the callback I am not getting NPE but when I use the callback I am getting NPE: http://pastebin.com/wc2ByiFz

Paisley

is your adapter in a seperate class? – Crosshead

Wait i am writing the solution – Arabel

Just make the adapter an inner class of your fragment or activity – Crosshead

Now that you updated this question, where is at com.ylg.link.CustomAdapter$1.onGroupExpand(CustomAdapter.java:149)? – Karlakarlan

Exactly the place where I am calling the call back.. after the three logs. – Paisley

Always check for null or try exception just like my example. if (mAdapterCallback.onMethodCallback != null ) { mAdapterCallback.onMethodCallback(); }. Please pay closer attention to my example as it works. – Karlakarlan

Added try and catch. I still get NPE issue in exception. I am not able to get the results. – Paisley

Answer 1

   public class CustomAdapter implements ExpandableListAdapter {

    Activity yourActivity
     public CustomAdapter(Activity yourActivity)
                    {

            this.yourActivity= yourActivity;

                }

    @Override
    public View getGroupView(int position, boolean isExpanded, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.menu_item, parent, false);
        }

        TextView text = (TextView) convertView.findViewById(android.R.id.text1);
        text.setText(items.get(position).getName());
        ImageView imageView = (ImageView) convertView.findViewById(R.id.imageIndicator);

        if (items.get(position).isHasChild() && items.get(position).getSubMenuItems().size() > 0)
            imageView.setVisibility(View.VISIBLE);
        else
            imageView.setVisibility(View.INVISIBLE);

        if (isExpanded)
            imageView.setImageResource(R.drawable.down);
        else
            imageView.setImageResource(R.drawable.next);

        return convertView;
    }

    @Override
    public View getChildView(final int childPosition, int groupPosition, boolean isExpanded, View convertView, final ViewGroup parent) {

        View view = convertView;

        if (view == null) {
            view = inflater.inflate(R.layout.expandable_list, parent, false);
        }
        ExpandableHeightListView childList = (ExpandableHeightListView) view.findViewById(R.id.childList);
        childList.setAdapter(new CustomAdapter(context, items.get(childPosition).getSubMenuItems()));
        childList.invalidate();
        parent.invalidate();

        final ExpandableHeightListView list = childList;
        childList.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            int previousItem = -1;

            @Override
            public void onGroupExpand(int groupPosition) {
                ArrayList<eMenuItem> tempItems = items.get(childPosition).getSubMenuItems();

                if (tempItems.get(groupPosition).getSubMenuItems().size() == 0) {
                     yourActivity.onYourClick(groupPosition);
                } else {
                    Toast.makeText(context, "Clicked on " + tempItems.get(groupPosition).getName(), Toast.LENGTH_SHORT).show();
                }

                if (groupPosition != previousItem)
                    list.collapseGroup(previousItem);

                previousItem = groupPosition;
                list.invalidate();
                parent.invalidate();
            }
        });
        return view;
    }
}

//Your Fragment

    public class yourActivity extends FragmentActivity{
            public void onYourClick(int groupPosition){
            }

Arabel

@ Ammar aly : can you please give me an example? What do you mean by onYourClick and paramenters please? – Paisley

Onyourclick is the method that you will call as callback in your fragment or in activity – Arabel

How do I link fragment with the adpter? – Paisley

It gives error the method onYourClick(int) is undefined for the type Activity? – Paisley

do you have any activity make a method in it – Arabel

Like what do you want from it? – Paisley

It is exactly the same like what you have done. listFragment.openGridViewData(tempItems.get(groupPosition).getName(), childPosition); – Paisley

And in FragmentActivity: public void openGridViewData(String name, int position) – Paisley

if method is there then your not calling it properly check the activity reference in constructor – Arabel

did you make constructor in your adapter – Arabel

public CustomAdapter(FragmentActivity gridActivity) { this.gridActivity = gridActivity; } – Paisley

what is your class name the activity you are calling – Arabel

public CustomAdapter(ListFragment listFragment) { this.listFragment= listFragment; } – Arabel

Yep. I added it now I am getting 03-17 13:25:58.372: E/AndroidRuntime(8210): java.lang.NullPointerException 03-17 13:25:58.372: E/AndroidRuntime(8210): at com.ylk.link.CustomAdapter$1.onGroupExpand(CustomAdapter.java:149) 03-17 13:25:58.372: E/AndroidRuntime(8210): at android.widget.ExpandableListView.handleItemClick(ExpandableListView.java:696) – Paisley

Refer to this #23740734 – Arabel

I am not sure why this NullpinterException is coming up because I am getting the log value correctly when clicking on the item I am getting this error only when I am trying to send the gridActivity.openGridViewData(tempItems.get(groupPosition).getName(), groupPosition); - I add to casting to for Fragment.. Something like this: ((MainActivity) gridActivity).openGridViewData(tempItems.get(groupPosition).getName(), groupPosition); – Paisley