Android Blog: March 2013

The following code explains you people's how to create the simple expandable list view.

first The Launcher Activity:
1.MyActivity.Java

import android.app.Activity;
import android.app.ExpandableListActivity;
import android.content.Context;
import android.os.Bundle;
import android.widget.ExpandableListView;

import java.util.ArrayList;

public class MyActivity extends Activity {
    private ExpandableListView mExpandableList;

    Context context;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        context=this;
mExpandableList = (ExpandableListView)findViewById(R.id.expandable_list);
 mExpandableList.setGroupIndicator(getResources().getDrawable(R.drawable.expandiconempty));
  ArrayList<Parent> arrayParents = new ArrayList<Parent>();
 ArrayList<String> arrayChildren = new ArrayList<String>();
//here we set the parents and the children
 for (int i = 0; i < 2; i++){
   //for each "i" create a new Parent object to set the title and the children
 Parent parent = new Parent();
 parent.setTitle("Parent " + i);
arrayChildren = new ArrayList<String>();
 for (int j = 0; j < 5; j++) {
arrayChildren.add("Child " + j);
}
parent.setArrayChildren(arrayChildren);
//in this array we add the Parent object. We will use the arrayParents at the setAdapter
 arrayParents.add(parent);
}
//sets the adapter that provides data to the list.
mExpandableList.setAdapter(new MyCustomAdapter(MyActivity.this,arrayParents));
mExpandableList.expandGroup(0);
mExpandableList.expandGroup(1);

    }
}

The custom Adapter class which binds the parent list-view ad child list-view with the adapters.

import android.content.Context;
import android.database.DataSetObserver;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;
import java.util.ArrayList;
public class MyCustomAdapter extends BaseExpandableListAdapter {
    private LayoutInflater inflater;
    private ArrayList<Parent> mParent;
    public MyCustomAdapter(Context context, ArrayList<Parent> parent){
        mParent = parent;
        inflater = LayoutInflater.from(context);
    }
    @Override
    //counts the number of group/parent items so the list knows how many times calls getGroupView() method
    public int getGroupCount() {
        return mParent.size();
    }

    @Override
    //counts the number of children items so the list knows how many times calls getChildView() method
    public int getChildrenCount(int i) {
        return mParent.get(i).getArrayChildren().size();
    }

    @Override
    //gets the title of each parent/group
    public Object getGroup(int i) {
        return mParent.get(i).getTitle();
    }
    @Override
    //gets the name of each item
    public Object getChild(int i, int i1) {
        return mParent.get(i).getArrayChildren().get(i1);
    }
    @Override
    public long getGroupId(int i) {
        return i;
    }
    @Override
    public long getChildId(int i, int i1) {
        return i1;
    }
    @Override
    public boolean hasStableIds() {
        return true;
    }
    @Override
    //in this method you must set the text to see the parent/group on the list
    public View getGroupView(int i, boolean b, View view, ViewGroup viewGroup) {

        if (view == null)

  {
            view = inflater.inflate(R.layout.parent, viewGroup,false);
        }


        TextView textView = (TextView) view.findViewById(R.id.list_item_text_view);
        //"i" is the position of the parent/group in the list
        textView.setText(getGroup(i).toString());

        //return the entire view
        return view;
    }

    @Override
    //in this method you must set the text to see the children on the list
    public View getChildView(int i, int i1, boolean b, View view, ViewGroup viewGroup) {
        if (view == null) {
            view = inflater.inflate(R.layout.child, viewGroup,false);
        }

        TextView textView = (TextView) view.findViewById(R.id.list_item_text_child);
        //"i" is the position of the parent/group in the list and 
        //"i1" is the position of the child
        textView.setText(mParent.get(i).getArrayChildren().get(i1));

        //return the entire view
        return view;
    }

    @Override
    public boolean isChildSelectable(int i, int i1) {
        return true;
    }

    @Override
    public void registerDataSetObserver(DataSetObserver observer) {
        /* used to make the notifyDataSetChanged() method work */
        super.registerDataSetObserver(observer);
    }
}

Parent Class with  setter and getter methods.

import java.util.ArrayList;

public class Parent {
    private String mTitle;
    private ArrayList<String> mArrayChildren;

    public String getTitle() {
        return mTitle;
    }

    public void setTitle(String mTitle) {
        this.mTitle = mTitle;
    }

    public ArrayList<String> getArrayChildren() {
        return mArrayChildren;
    }

    public void setArrayChildren(ArrayList<String> mArrayChildren) {
        this.mArrayChildren = mArrayChildren;
    }
}

main design file .

1.main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent"
        >
    <ExpandableListView android:id="@+id/expandable_list"
                        android:layout_width="fill_parent"
                        android:layout_height="fill_parent"
                        android:transcriptMode="alwaysScroll"
                        android:cacheColorHint="#00000000"

                        android:listSelector="@android:color/transparent"/>
</LinearLayout>

2. child.xml will be look like this .

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/list_item_child"
        android:gravity="center_vertical">


    <TextView android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:id="@+id/list_item_text_child"
              android:textSize="20sp"
              android:padding="10dp"
              android:layout_marginLeft="5dp"/>


</LinearLayout>

3. Parent.xml will be like this .

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/list_item">

<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:id="@+id/list_item_text_view"
android:textSize="20sp"
android:padding="10dp"
android:layout_weight="1"
android:layout_marginLeft="35dp" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="button"
android:focusable="false"
android:layout_gravity="right"
android:focusableInTouchMode="false"
android:id="@+id/button"/>

</LinearLayout>

one more thing both  child and parent .xml files will be your own custom files.

so you can design with you .

 happy coding....

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