ExpandableListView example

android.widget.ExpandableListView display two-level ListView: groups which can individually be expanded to show its children. The items come from the ExpandableListAdapter associated with this view.

Example:

ExpandableListView example

Create our custom MyBaseExpandableListAdapter extends BaseExpandableListAdapter, MyBaseExpandableListAdapter.java

package com.example.androidexpandablelistview;

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

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;

public class MyBaseExpandableListAdapter extends BaseExpandableListAdapter {
 
 private Context context;
    private List<String> listGroup;
    private HashMap<String, List<String>> listChild;

 public MyBaseExpandableListAdapter(Context c, List<String> lg,
            HashMap<String, List<String>> lc) {
  context = c;
  listGroup = lg;
  listChild = lc;
 }

 @Override
 public Object getChild(int groupPosition, int childPosition) {
  return listChild.get(listGroup.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) {
  
        if (convertView == null) {
            LayoutInflater infalInflater = 
              (LayoutInflater)context
              .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = infalInflater.inflate(R.layout.item_layout, null);
        }
 
        TextView textViewItem = 
          (TextView)convertView.findViewById(R.id.item);
        
        String text = (String)getChild(groupPosition, childPosition);
 
        textViewItem.setText(text);
        return convertView;
 }

 @Override
 public int getChildrenCount(int groupPosition) {
  return listChild.get(listGroup.get(groupPosition)).size();
 }

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

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

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

 @Override
 public View getGroupView(int groupPosition, 
   boolean isExpanded, View convertView, 
   ViewGroup parent) {
  
        if (convertView == null) {
            LayoutInflater infalInflater = (LayoutInflater)context
              .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = infalInflater.inflate(R.layout.group_layout, null);
        }
        
        String textGroup = (String)getGroup(groupPosition);
 
        TextView textViewGroup = (TextView)convertView.findViewById(R.id.group);
        textViewGroup.setText(textGroup);
 
        return convertView;
 }

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

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

}

/res/layout/group_layout.xml, layout of view of groups.

<?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:background="#000000"
    android:orientation="vertical"
    android:padding="8dp" >

    <TextView
        android:id="@+id/group"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textColor="@android:color/white"
        android:textStyle="bold" />

</LinearLayout>

/res/layout/item_layout.xml, the layout of the view of children.

<?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="55dip"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/item"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textStyle="italic" />

</LinearLayout>

/res/layout/activity_main.xml, main layout of our activity, with <ExpandableListView>.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="android-coding.blogspot.com"
        android:textStyle="bold" />

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

</LinearLayout>

MainActivity.java

package com.example.androidexpandablelistview;

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

import android.os.Bundle;
import android.app.Activity;
import android.widget.ExpandableListView;

public class MainActivity extends Activity {
 
 MyBaseExpandableListAdapter myBaseExpandableListAdapter;
    ExpandableListView myExpandableListView;
    List<String> myListForGroup;
    HashMap<String, List<String>> myMapForChild;
 

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  
  myExpandableListView = (ExpandableListView)
    findViewById(R.id.myexpandablelistview);
 
        initData();
 
        myBaseExpandableListAdapter = new 
          MyBaseExpandableListAdapter(this, myListForGroup, myMapForChild);
 
        myExpandableListView.setAdapter(myBaseExpandableListAdapter);
 }
 
 private void initData() {
  myListForGroup = new ArrayList<String>();
  myMapForChild = new HashMap<String, List<String>>();

        List<String> listGroupA = new ArrayList<String>();
        listGroupA.add("A - 1");
        listGroupA.add("A - 2");
        listGroupA.add("A - 3");

        List<String> listGroupB = new ArrayList<String>();
        listGroupB.add("B - 1");
 
        List<String> listGroupC = new ArrayList<String>();
        listGroupC.add("C - 1");
        listGroupC.add("C - 2");
        
        myListForGroup.add("Group A");
        myListForGroup.add("Group B");
        myListForGroup.add("Group C");
        
        myMapForChild.put(myListForGroup.get(0), listGroupA);
        myMapForChild.put(myListForGroup.get(1), listGroupB);
        myMapForChild.put(myListForGroup.get(2), listGroupC);
    }

}

Next: Detect user action on ExpandableListView, with various Listeners