ExpandableListView可以显示一个视图垂直滚动显示两级列表中的条目，这不同于列表视图（ListView）。ExpandableListView允许有两个层次：一级列表中有二级列表。
比如在手机设置中，对于分类，有很好的效果。手机版QQ也是这样的效果。

完整代码下载

demo

效果图片

使用ExpandableListView的整体思路

（1）给ExpandableListView设置适配器，那么必须先设置数据源。

（2）数据源，就是此处的适配器类ExpandableAdapter，此方法继承了BaseExpandableListAdapter，需要重写里面的10个方法。
数据源中，用到了自定义的View布局，此时根据自己的需求，来设置组和子项的布局样式。
getChildView()和getGroupView()方法设置自定义布局。

（3）数据源设置好，直接给ExpandableListView.setAdapter()即可实现此收缩功能。ExpandableListView的完整代码实现

完整代码：

activity_main.xml：在里面放置一个ExpandableListView控件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingBottom="@dimen/activity_vertical_margin"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"><ExpandableListViewandroid:id="@+id/expandableListView"android:layout_width="match_parent"android:layout_height="wrap_content"/></RelativeLayout>

item_group.xml：一级列表的item的布局

<?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="wrap_content"android:background="#cccccc"android:orientation="horizontal"><TextViewandroid:id="@+id/tv_group"android:layout_width="wrap_content"android:layout_height="30dp"android:gravity="center"android:text="group text"android:textColor="#000000"/></LinearLayout>

item_child.xml：二级列表的item的布局

<?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="wrap_content"android:gravity="center"android:orientation="horizontal"><ImageViewandroid:id="@+id/iv_child"android:layout_width="30dp"android:layout_height="30dp"android:src="@mipmap/ic_launcher"/><TextViewandroid:id="@+id/tv_child"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="item text"android:textColor="#000000"/></LinearLayout>

MainActivity.java：

package com.example.recyview;import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;public class MainActivity extends Activity {//Viewprivate ExpandableListView expandableListView;//Model：定义的数据private String[] groups = {"A", "B", "C"};//注意，字符数组不要写成{{"A1,A2,A3,A4"}, {"B1,B2,B3,B4，B5"}, {"C1,C2,C3,C4"}}private String[][] childs = {{"A1", "A2", "A3", "A4"}, {"A1", "A2", "A3", "B4"}, {"A1", "A2", "A3", "C4"}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);expandableListView = (ExpandableListView) findViewById(R.id.expandableListView);expandableListView.setAdapter(new MyExpandableListView());expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {@Overridepublic boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {Toast.makeText(MainActivity.this, "子条目"+childPosition, Toast.LENGTH_SHORT).show();return true;}});}//为ExpandableListView自定义适配器class MyExpandableListView extends BaseExpandableListAdapter {//返回一级列表的个数@Overridepublic int getGroupCount() {return groups.length;}//返回每个二级列表的个数@Overridepublic int getChildrenCount(int groupPosition) { //参数groupPosition表示第几个一级列表Log.d("smyhvae", "-->" + groupPosition);return childs[groupPosition].length;}//返回一级列表的单个item（返回的是对象）@Overridepublic Object getGroup(int groupPosition) {return groups[groupPosition];}//返回二级列表中的单个item（返回的是对象）@Overridepublic Object getChild(int groupPosition, int childPosition) {return childs[groupPosition][childPosition];  //不要误写成groups[groupPosition][childPosition]}@Overridepublic long getGroupId(int groupPosition) {return groupPosition;}@Overridepublic long getChildId(int groupPosition, int childPosition) {return childPosition;}//每个item的id是否是固定？一般为true@Overridepublic boolean hasStableIds() {return true;}//【重要】填充一级列表@Overridepublic View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {if (convertView == null) {convertView = getLayoutInflater().inflate(R.layout.item_group, null);} else {}TextView tv_group = (TextView) convertView.findViewById(R.id.tv_group);tv_group.setText(groups[groupPosition]);return convertView;}//【重要】填充二级列表@Overridepublic View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {if (convertView == null) {convertView = getLayoutInflater().inflate(R.layout.item_child, null);}ImageView iv_child = (ImageView) convertView.findViewById(R.id.iv_child);TextView tv_child = (TextView) convertView.findViewById(R.id.tv_child);//iv_child.setImageResource(resId);tv_child.setText(childs[groupPosition][childPosition]);return convertView;}//二级列表中的item是否能够被选中？可以改为true@Overridepublic boolean isChildSelectable(int groupPosition, int childPosition) {return true;}}}