ExpandableListView 安卓二级菜单

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    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"
    tools:context="com.smyhvae.expandablelistviewdemo.MainActivity">


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


</RelativeLayout>

<?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">

    <TextView
        android:id="@+id/tv_group"
        android:layout_width="wrap_content"
        android:layout_height="30dp"
        android:gravity="center"
        android:text="group text"
        />

</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="wrap_content"
              android:orientation="horizontal"
              android:gravity="center" >

    <ImageView
        android:id="@+id/iv_child"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:src="@mipmap/ic_launcher" />
    <TextView
        android:id="@+id/tv_child"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="item text" />


</LinearLayout>

package com.smyhvae.expandablelistviewdemo;

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;

public class MainActivity extends Activity {

    //View
    private 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"}};


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        expandableListView = (ExpandableListView) findViewById(R.id.expandableListView);

        expandableListView.setAdapter(new MyExpandableListView());

    }


    //为ExpandableListView自定义适配器
        class MyExpandableListView extends BaseExpandableListAdapter {

        //返回一级列表的个数
        @Override
        public int getGroupCount() {
            return groups.length;
        }

        //返回每个二级列表的个数
        @Override
        public 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）
        @Override
        public Object getGroup(int groupPosition) {
            return groups[groupPosition];
        }

        //返回二级列表中的单个item（返回的是对象）
        @Override
        public Object getChild(int groupPosition, int childPosition) {
            return childs[groupPosition][childPosition];  //不要误写成groups[groupPosition][childPosition]
        }

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

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

        //每个item的id是否是固定？一般为true
        @Override
        public boolean hasStableIds() {
            return true;
        }

        //【重要】填充一级列表
        @Override
        public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

            if (convertView == null) {
                convertView = getLayoutInflater().inflate(R.layout.item_group, null);
            }
            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
        @Override
        public 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
        @Override
        public boolean isChildSelectable(int groupPosition, int childPosition) {
            return true;
        }
    }


}