我无法创建第二个ListItem

Question

我有一个列表和一个包含子项的列表项。但我需要第二个listitem和第二个listitem的子项。那么如何在项目中添加第二，第三......项目和子项目？ *抱歉我的英语很差。

    package com.deneeme.deneme;

import java.util.ArrayList;

import com.deneeme.deneme.R;

import android.app.Activity;
import android.os.Bundle;
import android.util.SparseArray;
import android.view.Menu;
import android.widget.ExpandableListView;
import android.widget.TextView;

public class MainActivity extends Activity {
  // more efficient than HashMap for mapping integers to objects
  SparseArray<Group> groups = new SparseArray<Group>();

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    createData();
    ExpandableListView listView = (ExpandableListView) findViewById(R.id.listView);
    MyExpandableListAdapter adapter = new MyExpandableListAdapter(this,
        groups);
    listView.setAdapter(adapter);
  }

  public void createData() {
    for (int a = 0; a < 1; a++) {
      Group group = new Group("Elma");
      for (int b = 0; b < 1; b++) {
        group.children.add("E1");
        group.children.add("E2");
        group.children.add("E3");
      }
      groups.append(a, group);
    }
  }
}