Expandable ListView - Android

Expandable ListView:

•  Expandable ListView is used to group, that can individually expanded to show its children.
•  When the user touches the header it has the ability to expand and collapse the group.
•   In this example you can learn how to create a simple expandable listview as shown below. 

                                                

       1)Lets start a new project in eclipse as we created for earlier projects
       2)we need three xml to create a expandable list view,first xml is for the main list view ,second xml is for the list group and the third xml is for  child list view.
      3)Design your activity_main.xml with Expandable listview as shown below
                                                  

    4)Create a list_group.xml for the listview group and code as follows
                                                 

   5)Create another xml file named list_item.xml it contaoin only listview item.
                                                   

  6)Here we are going to use a custom adapter class to create the expandable listview,create a new class file named Expandablelistadpater.java and extend this from Baseexpandablelistadapter.java

  7)This Baseexpandablelistadapter provide some requierd methods to render listview

• Getgroupview( )-listgroup header view are returned
• Getchildview ( )-listchild view are returned

ExpandableListView.java:
 

 package com.example.expandablelist;
import java.util.HashMap;
import java.util.List;

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 int getGroupCount() {
        // TODO Auto-generated method stub
        return this._listDataHeader.size();    
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        // TODO Auto-generated method stub
        return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                .size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        // TODO Auto-generated method stub
        return this._listDataHeader.get(groupPosition);
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                .get(childPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        // TODO Auto-generated method stub
        return groupPosition;    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        // TODO Auto-generated method stub
        return childPosition;
    }

    @Override
    public boolean hasStableIds() {
        // TODO Auto-generated method stub
        return false;
    }

    @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.textView1);
        lblListHeader.setTypeface(null, Typeface.BOLD);
        lblListHeader.setText(headerTitle);

        return convertView;
    }

    @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.textView1);

        txtListChild.setText(childText);
        return convertView;
        // TODO Auto-generated method stub
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        // TODO Auto-generated method stub
        return false;
    }

}

   8) Next its time to code the main activity  

                 here i split and post the main activity ibn to two files 

                                                

                                                                            

   9)Add these three lines at  the end of the main activity which is used for header and child data 

               listDataChild.put(listDataHeader.get(0), top250);
            listDataChild.put(listDataHeader.get(1), nowShowing);

listDataChild.put(listDataHeader.get(2),comingSoon);     

 10)Now its time to run and test the project ,check with your emulator or device .