Expandable Listview in Android Example

Android, ExpandableListView is a View that shows items in a vertically scrolling two level list. Different from the listview by allowing two level groups which can individually be expanded to show.Expandable listview is a parent and childview to expand to click parent view to display childview in android.

MainActivity.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.bhaumik.expandablelistwithactivity.MainActivity"
    android:background="@color/MainActivityBackground">



    <ExpandableListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/expand_view" />

</RelativeLayout>

Create XML File to Parent Item Display in Layout

PrentItem.xml

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

    <TextView
        android:id="@+id/tv_parent_item"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="@color/WhiteColor"
        android:text="Parent Item"
        android:textSize="20dp"
        android:padding="5dp"
        android:layout_marginLeft="20dp"/>
</LinearLayout>

Create XML Layout file to Child Item in Listview

ChildItem.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/child_item_bg">
    <TextView
        android:id="@+id/tv_child_item"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textColor="@color/BlackColor"
        android:text="Child Item"
        android:textSize="20dp"
        android:padding="8dp"
        android:layout_marginLeft="80dp"/>
</LinearLayout>

MainActivity.java

package com.bhaumik.expandablelistwithactivity;

import android.content.Intent;
import android.media.MediaPlayer;
import android.support.design.widget.TabLayout;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.transition.Explode;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.Toast;

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

public class MainActivity extends FragmentActivity {

    ExpandableListView expandableListView;

    List<String> main_title = new ArrayList<>();
    List<String> android_list = new ArrayList<>();
    List<String> java_list = new ArrayList<>();
    List<String> php_list = new ArrayList<>();
    HashMap<String,List<String>> child_list = new HashMap<String,List<String>>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

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

        String[] cource_title = getResources().getStringArray(R.array.cource_title);
        String[] android_items = getResources().getStringArray(R.array.android_item);
        String[] java_items = getResources().getStringArray(R.array.java_item);
        String[] php_items = getResources().getStringArray(R.array.php_item);

        for(String heading : cource_title)
        {
            main_title.add(heading);
        }
        for (String android : android_items)
        {
            android_list.add(android);
        }
        for (String java : java_items)
        {
            java_list.add(java);
        }
        for (String php : php_items)
        {
            php_list.add(php);
        }

        child_list.put(main_title.get(0),android_list);
        child_list.put(main_title.get(1),java_list);
        child_list.put(main_title.get(2),php_list);

        final MyAdapter myAdapter = new MyAdapter(MainActivity.this,main_title,child_list);
        expandableListView.setAdapter(myAdapter);

    }
}

Create Adapter to set Parent And Child item Data in listview.

MyAdapter.java

package com.bhaumik.expandablelistwithactivity;

import android.content.Context;
import android.content.Intent;
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;

/**
 * Created by Bhaumik on 3/23/2017.
 */

public class MyAdapter extends BaseExpandableListAdapter{

    Context context;
    List<String> cource_title;
    HashMap<String,List<String>> child_title;

    public MyAdapter(Context context, List<String> cource_title, HashMap<String, List<String>> child_title) {
        this.context = context;
        this.cource_title = cource_title;
        this.child_title = child_title;
    }

    @Override
    public int getGroupCount() {
        return cource_title.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return child_title.get(cource_title.get(groupPosition)).size();
    }

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

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return child_title.get(cource_title.get(groupPosition)).get(childPosition);
    }

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

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

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

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

        String titles = (String) this.getGroup(groupPosition);

        if(convertView == null)
        {
            LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
            convertView = layoutInflater.inflate(R.layout.parent_item,null);
        }
        TextView textView = (TextView) convertView.findViewById(R.id.tv_parent_item);
        textView.setText(titles);

        return convertView;
    }

    @Override
    public View getChildView(final int groupPosition, final int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {

        String titles = (String) this.getChild(groupPosition,childPosition);

        if(convertView == null)
        {
            LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
            convertView = layoutInflater.inflate(R.layout.child_item,null);
        }
        TextView textView = (TextView) convertView.findViewById(R.id.tv_child_item);
        textView.setText(titles);

        textView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(context,DetailActivity.class);
                intent.putExtra("text",child_title.get(cource_title.get(groupPosition)).get(childPosition));
                context.startActivity(intent);
            }
        });
        return convertView;
    }

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