Thursday, May 19, 2011

Android Expandable ListView

A view that shows items in a vertically scrolling two-level list. This differs from the ListView by allowing two levels: groups which can individually be expanded to show its children. The items come from the ExpandableListAdapter associated with this view.

Steps to develop Expandable List :
-> Initialize the Expandable List View
-> Construct the Expandable List Adapter
-> Set the Adapter to Expandable List View


Initialize the Expandable List View
 ExpandableListView explvList;
 explvList = (ExpandableListView)findViewById(R.id.explvList);
Construct the Expandable List Adapter 
    public class ExpLvAdapter extends BaseExpandableListAdapter
    {
        @Override
        public Object getChild(int groupPosition, int childPosition)
        {           
            return childPosition;
        }

        @Override
        public long getChildId(int groupPosition, int childPosition)
        {
           
            return childPosition;
        }

        @Override
        public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent)
        {
            TextView tv = null;
            tv = new TextView(Home.this);
            tv.setText("ChildView "+groupPosition);           
            tv.setPadding(30, 0, 0, 0);
            return tv;
        }
        @Override
        public int getChildrenCount(int groupPosition)
        {   
            return children[groupPosition].length;
        }

        @Override
        public Object getGroup(int groupPosition)
        {
            return groupPosition;
        }

        @Override
        public int getGroupCount()
        {
           
            return 2;
        }

        @Override
        public long getGroupId(int groupPosition)
        {
           
            return groupPosition;
        }

        @Override
        public View getGroupView(int groupPosition, boolean isExpanded,
                View convertView, ViewGroup parent)
        {
            TextView tv = null;
            tv = new TextView(Home.this);
            tv.setText("GroupView "+groupPosition);           
            tv.setPadding(30, 0, 0, 0);
            return tv;
        }

        @Override
        public boolean hasStableIds()
        {
            return false;
        }

        @Override
        public boolean isChildSelectable(int groupPosition, int childPosition)
        {
           
            return true;
        }
    }


Set the Adapter to Expandable List View
explvList.setAdapter(new ExpLvAdapter());
Output:

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