Expandable ListView

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:layout_height="match_parent"
    tools:context="com.tutorialscafe.readallsms.MainActivity">

    <ExpandableListView
        android:childDivider="#0000"
        android:layout_margin="10dp"
        android:id="@+id/lvExp"
        android:layout_height="match_parent"
        android:layout_width="match_parent"/>

</LinearLayout>

ActivityMainExpandableListView.java

package com.tutorialscafe.readallsms;


import android.app.Activity;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

/**
 * ReadAllSMS
 * Created by Ali Tamoor on 6/1/2017.
 */

public class MainActivity extends AppCompatActivity{

    ExpandableListAdapter listAdapter;
    ExpandableListView expListView;
    List<String> listDataHeader;
    HashMap<String, List<String>> listDataChild;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        expListView = (ExpandableListView) findViewById(R.id.lvExp);
        prepareListData();
        listAdapter = new ExpandableListAdapter(this, listDataHeader, listDataChild);
        expListView.setAdapter(listAdapter);

        expListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
            @Override
            public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
                Toast.makeText(MainActivity.this, " " + listAdapter.getChild(groupPosition,childPosition), Toast.LENGTH_SHORT).show();
                return true;
            }
        });
    }

    private void prepareListData() {
        listDataHeader = new ArrayList<String>();
        listDataChild = new HashMap<String, List<String>>();

        // Adding child data
        listDataHeader.add("1-Introduction");
        listDataHeader.add("2-Bsics of C++");
        listDataHeader.add("3-Program Structure");
        listDataHeader.add("4-Compund Data Types");
        listDataHeader.add("5-Classes");

        // Adding child data
        List<String> introduction = new ArrayList<String>();
        introduction.add("Compiler");

        List<String> basic = new ArrayList<String>();
        basic.add("Constrol Structure");
        basic.add("Functions");
        basic.add("Overloads and Teplates");
        basic.add("Name Visibilities");

        List<String> structure = new ArrayList<String>();
        structure.add("Arrays");
        structure.add("Charater Sequesnce");
        structure.add("Pointers");
        structure.add("Dynamic Memory");
        structure.add("Data Structure");
        structure.add("Other Data Types");

        List<String> datatupes = new ArrayList<String>();
        datatupes.add("Arrays");
        datatupes.add("Charater Sequesnce");
        datatupes.add("Pointers");
        datatupes.add("Dynamic Memory");
        datatupes.add("Data Structure");
        datatupes.add("Other Data Types");

        List<String> classes = new ArrayList<String>();
        classes.add("CLasses (I)");
        classes.add("Classes (II)");
        classes.add("Special Members");
        classes.add("Friendship and inhereitence");
        classes.add("Polymorphism");

        listDataChild.put(listDataHeader.get(0), introduction); // Header, Child data
        listDataChild.put(listDataHeader.get(1), basic);
        listDataChild.put(listDataHeader.get(2), structure);
        listDataChild.put(listDataHeader.get(3), datatupes);
        listDataChild.put(listDataHeader.get(4), classes);
    }
}

ExpandableListViewAdapter.java

package com.tutorialscafe.readallsms;

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;

import java.util.HashMap;
import java.util.List;

/**
 * ReadAllSMS
 * Created by Ali Tamoor on 6/3/2017.
 */


public class ExpandableListAdapter extends BaseExpandableListAdapter {

    private Context _context;
    private List<String> _listDataHeader; // header titles
    // child data in format of header title, child title
    private HashMap<String, List<String>> _listDataChild;

    public ExpandableListAdapter(Context context, List<String> listDataHeader,
                                 HashMap<String, List<String>> listChildData) {
        this._context = context;
        this._listDataHeader = listDataHeader;
        this._listDataChild = listChildData;
    }

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

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

    @Override
    public View getChildView(int groupPosition, final 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() {
        return false;
    }

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

lexpandable_list_group_view.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="2dp"
    android:background="#58D68D">


    <TextView
        android:paddingLeft="40dp"
        android:height="50dp"
        android:gravity="center_vertical"
        android:text="Here your Group Goes"
        android:id="@+id/lblListHeader"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="17dp"
        android:textColor="#FFFF" />

</LinearLayout>

list_view_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="50dip"
    android:orientation="vertical" >

    <TextView
        android:background="#F0F3F4"
        android:layout_marginLeft="5dp"
        android:layout_marginRight="5dp"
        android:gravity="center_vertical"
        android:text="@string/app_name"
        android:height="50dp"
        android:id="@+id/lblListItem"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="17dip"
        android:paddingTop="5dp"
        android:paddingBottom="5dp"
        android:paddingLeft="50dp"
         />

</LinearLayout>