如何在Android ListView中添加子项？

我已经使用以下布局和ListActivity类从 Vogella.com获取了android listView.

RowLayout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://scheR_522_11845@as.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >

    <ImageView
        android:id="@+id/icon"
        android:layout_width="22px"
        android:layout_height="22px"
        android:layout_marginLeft="4px"
        android:layout_marginRight="10px"
        android:layout_marginTop="4px"
        android:src="@drawable/icon" >
    </ImageView>

    <TextView
        android:id="@+id/label"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@+id/label"
        android:textSize="20px" >
    </TextView>

</LinearLayout>

@H_865_2@myListActivity.java

package de.vogella.android.listactivity;

import android.app.ListActivity;
import android.os.bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class MyListActivity extends ListActivity {
  public void onCreate(Bundle iciclE) {
    super.onCreate(iciclE);
    String[] values = new String[] { "Android","iPhone","WindowsMobile","BlackBerry","WebOS","Ubuntu","Windows7","Max OS X","Linux","OS/2" };
    // use your own layout
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.rowlayout,R.id.label,values);
    setlistadapter(adapter);
  }

  @Override
  protected void onListItemClick(ListView l,View v,int position,long id) {
    String item = (String) getlistadapter().getItem(position);
    Toast.makeText(this,item + " SELEcted",Toast.LENGTH_LONG).show();
  }
}

我想在textView下面添加一个子项,并将全文部分保留在每行的中心.我该怎么做？