Simple Expandable List Example

Description:
This example shows how to create Expandable list using simple default adapter.

Algorithm:

1.) Create a new project by File-> New -> Android Project name it SimpleExpandableListExample.

2.) Run for output.

Steps:

1.) Create a project named SimpleExpandableListExample and set the information as stated in the image.

Build Target: Android 2.3.3
Application Name: SimpleExpandableListExample
Package Name: com.example
Activity Name: SimpleExpandableListExampleActivity
Min SDK Version: 10

2.) Open SimpleExpandableListExampleActivity.java file and write following code there:

package com.example;

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

import android.app.ExpandableListActivity;
import android.os.Bundle;
import android.widget.ExpandableListAdapter;
import android.widget.SimpleExpandableListAdapter;

public class SimpleExpandableListExampleActivity extends ExpandableListActivity {
    private static final String NAME = "NAME";
    private static final String IS_EVEN = "IS_EVEN";
    
    private ExpandableListAdapter mAdapter;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        List<Map<String, String>> groupData = new ArrayList<Map<String, String>>();
        List<List<Map<String, String>>> childData = new ArrayList<List<Map<String, String>>>();
        for (int i = 0; i < 20; i++) {
            Map<String, String> curGroupMap = new HashMap<String, String>();
            groupData.add(curGroupMap);
            curGroupMap.put(NAME, "Item " + i);
            curGroupMap.put(IS_EVEN, (i % 2 == 0) ? "This group is even" : "This group is odd");
            
            List<Map<String, String>> children = new ArrayList<Map<String, String>>();
            for (int j = 0; j < 5; j++) {
                Map<String, String> curChildMap = new HashMap<String, String>();
                children.add(curChildMap);
               // curChildMap.put(NAME, "Child " + j);
                curChildMap.put(IS_EVEN, (j % 2 == 0) ? "Hello " + j: "Good Morning "+ j);
            }
            childData.add(children);
        }
        
        // Set up our adapter
        mAdapter = new SimpleExpandableListAdapter(
                this,
                groupData,
                android.R.layout.simple_expandable_list_item_1,
                new String[] { NAME, IS_EVEN },
                new int[] { android.R.id.text1, android.R.id.text2 },
                childData,
                android.R.layout.simple_expandable_list_item_2,
                new String[] { NAME, IS_EVEN },
                new int[] { android.R.id.text1, android.R.id.text2 }
                );
        setListAdapter(mAdapter);
    }

}

3.) Compile and build the project.

About the Author

Leave a Reply 7 comments

Jose - May 27, 2012 Reply

Hi.

I need that my class extends also from Activity, in my View appears more data, no only an ExpandableListActivity. How could I do this?

Thanks.

ariel - September 22, 2012 Reply

Muchas gracias… de gran utilidad :)

Michael - October 25, 2012 Reply

I’ve read hundreds (if not thousands) of tutorials and examples while developing Android applications, but I never wrote any comment if anything helped me – yes I will change that about myself.

After realizing that this saved my damned day I just wanted to say: Thank you!

Sagar - November 7, 2012 Reply

Is it possible to open expandableList on a button click in a activity ? I did succeed but list is hidden and not shown completely. For example like drop down list.

-coffee- - May 26, 2013 Reply

Thanks a lot! One question: where will the strings “This group is even” and “This group is odd” go?

Gonzalo - August 7, 2013 Reply

At last, a simple example of an expandable list, it is difficult to find them.
Just a couple of things:
* You are using a simple_expandable_list_item_1 for the main list, which have just one TextView, but you use two text for each item of the main list; so, the second one(key=IS_EVEN), it is not used (This group is even/odd).
* Secondly, you use a simple_expandable_list_item_2 for the children, these are the lists that are inside the main list; but you just put of them inside the children the list, the other is simply commented (// curChildMap.put(NAME, “Child ” + j)). I suppose you just want to use one of them, and this is because it appear a blank line inside each child item.
Anyway, thank you for your example.

Shashi Kumar - September 24, 2013 Reply

Best tutorial I’ve ever come across.

Hats off to you. Thank you.

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