第一步创建布局

主布局

<ExpandableListView
    android:id="@+id/expend_list"
    android:layout_width="match_parent"
    android:layout_height="match_parent"></ExpandableListView>

父item布局

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/label_group_normal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@android:color/holo_blue_light"
    android:gravity="center_vertical"
    android:paddingBottom="8dp"
    android:paddingLeft="32dp"
    android:paddingTop="8dp"
    android:textColor="@android:color/white"
    android:textSize="20sp"
    tools:text="测试数据"/>

子item布局

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/expand_child"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:textSize="16sp"
    android:paddingTop="8dp"
    android:paddingBottom="8dp"
    tools:text="测试数据"/>

第二步适配器

    public class MyExtendableListViewAdapter extends BaseExpandableListAdapter {

        @Override
        // 获取分组的个数
        public int getGroupCount() {
            return groupString.length;
        }

        //获取指定分组中的子选项的个数
        @Override
        public int getChildrenCount(int groupPosition) {
            return childString[groupPosition].length;
        }

        //        获取指定的分组数据
        @Override
        public Object getGroup(int groupPosition) {
            return groupString[groupPosition];
        }

        //获取指定分组中的指定子选项数据
        @Override
        public Object getChild(int groupPosition, int childPosition) {
            return childString[groupPosition][childPosition];
        }

        //获取指定分组的ID, 这个ID必须是唯一的
        @Override
        public long getGroupId(int groupPosition) {
            return groupPosition;
        }

        //获取子选项的ID, 这个ID必须是唯一的
        @Override
        public long getChildId(int groupPosition, int childPosition) {
            return childPosition;
        }

        //分组和子选项是否持有稳定的ID, 就是说底层数据的改变会不会影响到它们
        @Override
        public boolean hasStableIds() {
            return true;
        }
        /**
         *
         * 获取显示指定组的视图对象
         *
         * @param groupPosition 组位置
         * @param isExpanded 该组是展开状态还是伸缩状态
         * @param convertView 重用已有的视图对象
         * @param parent 返回的视图对象始终依附于的视图组
         */
// 获取显示指定分组的视图
        @Override
        public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
            GroupViewHolder groupViewHolder;
            if (convertView == null){
                convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.partent_item,parent,false);
                groupViewHolder = new GroupViewHolder();
                groupViewHolder.tvTitle = (TextView)convertView.findViewById(R.id.label_group_normal);
                convertView.setTag(groupViewHolder);
            }else {
                groupViewHolder = (GroupViewHolder)convertView.getTag();
            }
            groupViewHolder.tvTitle.setText(groupString[groupPosition]);
            return convertView;
        }
        /**
         *
         * 获取一个视图对象，显示指定组中的指定子元素数据。
         *
         * @param groupPosition 组位置
         * @param childPosition 子元素位置
         * @param isLastChild 子元素是否处于组中的最后一个
         * @param convertView 重用已有的视图(View)对象
         * @param parent 返回的视图(View)对象始终依附于的视图组
         * @return
         * @see android.widget.ExpandableListAdapter#getChildView(int, int, boolean, android.view.View,
         *      android.view.ViewGroup)
         */

        //取得显示给定分组给定子位置的数据用的视图
        @Override
        public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
            ChildViewHolder childViewHolder;
            if (convertView==null){
                convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.child_item,parent,false);
                childViewHolder = new ChildViewHolder();
                childViewHolder.tvTitle = (TextView)convertView.findViewById(R.id.expand_child);
                convertView.setTag(childViewHolder);

            }else {
                childViewHolder = (ChildViewHolder) convertView.getTag();
            }
            childViewHolder.tvTitle.setText(childString[groupPosition][childPosition]);
            return convertView;
        }

        //指定位置上的子元素是否可选中
        @Override
        public boolean isChildSelectable(int groupPosition, int childPosition) {
            return true;
        }

         class GroupViewHolder {
            TextView tvTitle;
        }

         class ChildViewHolder {
            TextView tvTitle;

        }
    }

第三步使用及设置数据源

public String[] groupString = {"射手", "辅助", "坦克", "法师"};
public String[][] childString = {
        {"孙尚香", "后羿", "马可波罗", "狄仁杰"},
        {"孙膑", "蔡文姬", "鬼谷子", "杨玉环"},
        {"张飞", "廉颇", "牛魔", "项羽"},
        {"诸葛亮", "王昭君", "安琪拉", "干将"}

};

expandableListView=findViewById(R.id.expend_list);
expandableListView.setAdapter(new MyExtendableListViewAdapter());
//设置分组的监听
expandableListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
    @Override
    public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
        Toast.makeText(getApplicationContext(), groupString[groupPosition], Toast.LENGTH_SHORT).show();
        return false;
    }

});
expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
    @Override
    public void onGroupExpand(int groupPosition) {
        int count = new MyExtendableListViewAdapter().getGroupCount();
        for(int i = 0;i < count;i++){
            if (i!=groupPosition){
                expandableListView.collapseGroup(i);
            }
        }
    }
});
//设置子项布局监听
expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
    @Override
    public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
        Toast.makeText(getApplicationContext(), childString[groupPosition][childPosition], Toast.LENGTH_SHORT).show();
        return true;

    }
});

其中设置单个展开代码为：

expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
    @Override
    public void onGroupExpand(int groupPosition) {
        int count = new MyExtendableListViewAdapter().getGroupCount();
        for(int i = 0;i < count;i++){
            if (i!=groupPosition){
                expandableListView.collapseGroup(i);
            }
        }
    }
});

设置箭头在右边在主布局和父item布局中加入

android:layoutDirection="rtl"