Android 关于ExpandableListView二级菜单的问题

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

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:padding="15dp" >

<TextView
android:id="@+id/tv_group"
android:layout_width="match_parent"
android:layout_height="40dp"
android:textColor="#000000"
android:layout_marginLeft="10dp"
android:textSize="15sp"
android:gravity="left|center_vertical"
/>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
>

<TextView
android:id="@+id/user_name"
android:layout_width="match_parent"
android:layout_height="40dp"
android:textColor="#000000"
android:textSize="15sp"
android:layout_marginLeft="10dp"
android:gravity="left|center_vertical"
/>
</LinearLayout>

package com.example.text;

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

import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.TextView;

public class MainActivity extends Activity {
private ExpandableListView expandableListView;
private List<Map<String, Object>> data_list = new ArrayList<Map<String, Object>>();
private List<Map<String, Object>> data_list1 = new ArrayList<Map<String, Object>>();
private String[] content = { "设备", "设备", "设备", "设备", "设备", "设备", "设备",
"设备", "设备", "设备" };
private String[] content1 = { "机型类别", "机型类别", "机型类别", "机型类别", "机型类别",
"机型类别", "机型类别" };
private MyAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

expandableListView = (ExpandableListView) findViewById(R.id.expandableListView);
data();
data1();
adapter = new MyAdapter(data_list, data_list1);
expandableListView.setAdapter(adapter);

}

public class MyAdapter extends BaseExpandableListAdapter {
List<Map<String, Object>> data_list;
List<Map<String, Object>> data_list1;

public MyAdapter(List<Map<String, Object>> data_list,
List<Map<String, Object>> data_list1) {
this.data_list = data_list;
this.data_list1 = data_list1;
}

@Override
public int getGroupCount() {
return data_list1.size();
}

@Override
public int getChildrenCount(int groupPosition) {
return data_list.size();
}

@Override
public Object getGroup(int groupPosition) {
return data_list1.get(groupPosition);
}

@Override
public Object getChild(int groupPosition, int childPosition) {
return data_list.get(groupPosition).get(childPosition);
}

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

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

@Override
public boolean hasStableIds() {
return true;
}

/**
* 显示：group
*/
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
ViewGroupHolder holder;
if (convertView == null) {
convertView = LayoutInflater.from(MainActivity.this).inflate(
R.layout.lv_group, null);
holder = new ViewGroupHolder();
holder.tv_group = (TextView) convertView
.findViewById(R.id.tv_group);
convertView.setTag(holder);
} else {
holder = (ViewGroupHolder) convertView.getTag();
}
holder.tv_group.setText((String) data_list1.get(groupPosition).get(
"content1"));
return convertView;

}

/**
* 显示：child
*/
@Override
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
ViewChildrenHolder holder;
if (convertView == null) {
convertView = LayoutInflater.from(MainActivity.this).inflate(
R.layout.lv_children, null);
holder = new ViewChildrenHolder();
holder.tv_name = (TextView) convertView
.findViewById(R.id.user_name);

convertView.setTag(holder);
} else {
holder = (ViewChildrenHolder) convertView.getTag();
}
holder.tv_name.setText((String) data_list.get(childPosition).get(
"content"));

return convertView;
}

class ViewGroupHolder {
TextView tv_group;
}

class ViewChildrenHolder {
TextView tv_name;
}

@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return false;
}

}

private void data() {
for (int i = 0; i < content.length; i++) {
Map<String, Object> map = new HashMap<String, Object>();
map.put("content", content[i]);
data_list.add(map);
}
}

private void data1() {
for (int j = 0; j < content1.length; j++) {
Map<String, Object> map1 = new HashMap<String, Object>();
map1.put("content1", content1[j]);
data_list1.add(map1);
}
}
}