How to Develop Expandable Lists on Android

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:

Installing Android Applications on your Mobile

In order to install android application on your device there are 2 Ways.
-> Directly from Android Market Place
-> Manually if We have .apk file
Directly form Android Market Place:
Go to below link (Link to Android Market place). There you find lot of categorized  applications. From that you will directly found install option.
https://market.android.com/
Manually if we have apk file:
-> Copy the apk file into SDCARD
->Install third party applications like Astro File Manager, Application Installer if you mobile do not contain any default Application Installer.
https://market.android.com/details?id=com.metago.astro&feature=search_result  (Link to Astro File Manager)
->After installing the app open the app.
->It list all the apps in the sdcard.
->Click on the that u want to install.
->There you found install button.
That's it.