ExpandableListView

>extends ListView

>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.

>Following is an demo application: Click Here to download source code

Main Activity

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.ExpandableListView;

import android.widget.ExpandableListView.OnChildClickListener;

import android.widget.Toast;

public class MainActivity extends Activity {

ExpandableListAdapter expandableListAdapter;

ExpandableListView expandableListView;

List<String> parentListHeader;

HashMap<String, List<String>> childListData;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main_layout);

initializeDisplayElements();

prepareExpandableListData();

expandableListAdapter = new ExpandableListAdapter(this,

parentListHeader, childListData);

expandableListView.setAdapter(expandableListAdapter);

expandableListView.setOnChildClickListener(new OnChildClickListener() {

@Override

public boolean onChildClick(ExpandableListView parent, View v,

int groupPosition, int childPosition, long id) {

Toast.makeText(

getApplicationContext(),

parentListHeader.get(groupPosition)

+ " : "

+ childListData.get(

parentListHeader.get(groupPosition))

.get(childPosition), Toast.LENGTH_SHORT)

.show();

return false;

}

});

}

/**

* This method is used to prepare the expandable list data parent and

* corresponding child items.

*/

private void prepareExpandableListData() {

parentListHeader = new ArrayList<String>();

childListData = new HashMap<String, List<String>>();

// adding parent data

parentListHeader.add("Micromax");

parentListHeader.add("Moto");

parentListHeader.add("Samsung");

// adding child data

List<String> micromax = new ArrayList<String>();

micromax.add("micromax Canvas Nitro");

micromax.add("micromax Canvas Knight");

micromax.add("micromax gold");

List<String> moto = new ArrayList<String>();

moto.add("moto-G");

moto.add("moto-E");

moto.add("moto-G2");

List<String> samsung = new ArrayList<String>();

samsung.add("samsung grand");

samsung.add("samsung Note 2");

samsung.add("samsung Galaxy");

childListData.put(parentListHeader.get(0), micromax);

childListData.put(parentListHeader.get(1), moto);

childListData.put(parentListHeader.get(2), samsung);

}

/**

* This method is used to initialize display elements present on layout

*/

private void initializeDisplayElements() {

expandableListView = (ExpandableListView) findViewById(R.id.expandableListView1);

}

}

 ExpandableListAdapter

import java.util.HashMap;

import java.util.List;

import com.example.expandablelist.R;

import android.content.Context;

import android.graphics.Typeface;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseExpandableListAdapter;

import android.widget.TextView;

public class ExpandableListAdapter extends BaseExpandableListAdapter {

private Context _context;

private List<String> _listDataHeader;

private HashMap<String, List<String>> _listDataChild;

public ExpandableListAdapter(Context context, List<String> listDataHeader,

HashMap<String, List<String>> listDataChild) {

this._context = context;

this._listDataHeader = listDataHeader;

this._listDataChild = listDataChild;

}

@Override

public Object getChild(int groupPosition, int childPosition) {

return this._listDataChild.get(this._listDataHeader.get(groupPosition))

.get(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) {

final String childText = (String) getChild(groupPosition, childPosition);

if (convertView == null) {

LayoutInflater infalInflater = (LayoutInflater) this._context

.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

convertView = infalInflater.inflate(R.layout.list_item, null);

}

TextView txtListChild = (TextView) convertView

.findViewById(R.id.lblListItem);

txtListChild.setText(childText);

return convertView;

}

@Override

public int getChildrenCount(int groupPosition) {

return this._listDataChild.get(this._listDataHeader.get(groupPosition))

.size();

}

@Override

public Object getGroup(int groupPosition) {

return this._listDataHeader.get(groupPosition);

}

@Override

public int getGroupCount() {

return this._listDataHeader.size();

}

@Override

public long getGroupId(int groupPosition) {

return groupPosition;

}

@Override

public View getGroupView(int groupPosition, boolean isExpanded,

View convertView, ViewGroup parent) {

String headerTitle = (String) getGroup(groupPosition);

if (convertView == null) {

LayoutInflater infalInflater = (LayoutInflater) this._context

.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

convertView = infalInflater.inflate(R.layout.list_group, null);

}

TextView lblListHeader = (TextView) convertView

.findViewById(R.id.lblListHeader);

lblListHeader.setTypeface(null, Typeface.BOLD);

lblListHeader.setText(headerTitle);

return convertView;

}

@Override

public boolean hasStableIds() {

// TODO Auto-generated method stub

return false;

}

@Override

public boolean isChildSelectable(int groupPosition, int childPosition) {

// TODO Auto-generated method stub

return true;

}

}