Question

Can we have 3 different ExpandableLists in same layout i.e., in main.xml? If so can we use them differently in terms of android:list?

I have a requirement that I need to implement 3 individual expandableLists in the same layout. Can it be done?

Answer 1

Yes you can. I imagine simply using different ids would be more straight forward than android:list. But I wonder, are you trying to achieve an expandable list with 3 group rows and 1 group of child rows under each? Such that these are connected and look seamless? If so you can do it with one expandable list. Just an fyi. If that was your intention, I’ll get you a sample code to show you how it’s done. It’s very easy.

EDIT: The reason you are getting that error is because you’re most probably trying to use an expandablelistactivity class, which assumes (practically) that there will only be one expandable list in the activity. You should use a regular activity class. Here is what i’ve just tested and works.

package com.mango.stackoverflow;

import android.os.Bundle;
import android.app.Activity;
import android.view.Gravity;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.BaseExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ExpandableListView TestExpandListView1 = (ExpandableListView) findViewById(R.id.expandableListView1);
        ExpandableListView TestExpandListView2 = (ExpandableListView) findViewById(R.id.expandableListView2);
        ExpandableListView TestExpandListView3 = (ExpandableListView) findViewById(R.id.expandableListView3);
        TestExpandableListAdapter TestExpandAdapter = new TestExpandableListAdapter();
        TestExpandListView1.setAdapter(TestExpandAdapter);
        TestExpandListView2.setAdapter(TestExpandAdapter);
        TestExpandListView3.setAdapter(TestExpandAdapter);
    }


    public class TestExpandableListAdapter extends BaseExpandableListAdapter {

        private String[] groups = { "People Names -- 1st GROUP", "Dog Names", "Cat Names", "Fish Names" };
        private String[][] children = {
                { "Arnold", "Barry", "Chuck", "David" },
                { "Ace", "Bandit", "Cha-Cha", "Deuce" },
                { "Fluffy", "Snuggles" },
                { "Goldy", "Bubbles" }
        };

        public Object getChild(int groupPosition, int childPosition) {
            return children[groupPosition][childPosition];
        }

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

        public int getChildrenCount(int groupPosition) {
            return children[groupPosition].length;
        }

        public TextView getGenericView() {
            // Layout parameters for the ExpandableListView
            AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
                    ViewGroup.LayoutParams.MATCH_PARENT, 64);

            TextView textView = new TextView(MainActivity.this);
            textView.setLayoutParams(lp);
            // Center the text vertically
            textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
            // Set the text starting position
            textView.setPadding(36, 0, 0, 0);
            return textView;
        }

        public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
                View convertView, ViewGroup parent) {
            TextView textView = getGenericView();
            textView.setText(getChild(groupPosition, childPosition).toString());
            return textView;
        }

        public Object getGroup(int groupPosition) {
            return groups[groupPosition];
        }

        public int getGroupCount() {
            return groups.length;
        }

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

        public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
                ViewGroup parent) {
            TextView textView = getGenericView();
            textView.setText(getGroup(groupPosition).toString());
            return textView;
        }

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

        public boolean hasStableIds() {
            return true;
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
}

I’m posting the xml as well, in case I wasn’t being clear about the id instantiation (PLEASE take note — Although i used “wrap_content” for the layout_height in the xml for the sake of speed, it is DEFINITELY not best practices to do so for expandablelistviews or any listview, it uses much more resources than the other alternatives would):

<RelativeLayout 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" >

    <ExpandableListView
        android:id="@+id/expandableListView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" >
    </ExpandableListView>

        <ExpandableListView
        android:id="@+id/expandableListView2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/expandableListView1" >
    </ExpandableListView>

                <ExpandableListView
        android:id="@+id/expandableListView3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/expandableListView2" >
    </ExpandableListView>


</RelativeLayout>

And here is a picture

• That being posted, I don’t want to instruct you how to do your code, but just to level with you. having this many expandable listviews in one activity, especially if you’re inflating views is not going to be the most… elegant implemention. I don’t know what you’re trying to do, but if they are to be connected like mine were or even just in a vertical panel, then it can be done with just one and be much more efficient.