expandablelistView 可展开的列表

这个东西用法基本固定，不知道能不能做三级的展开。

界面代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ExpandableListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:childIndicator="@mipmap/ic_launcher"
        android:childIndicatorStart="380dp"
        android:childIndicatorEnd="410dp"/>
</LinearLayout>

主程序代码

package com.example.expandablelistview

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.Gravity
import android.view.View
import android.view.ViewGroup
import android.widget.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val adapter = object:BaseExpandableListAdapter()
        {
            internal var logos = intArrayOf(R.drawable.p, R.drawable.z, R.drawable.t)
            private val armTypes = arrayOf("神族兵种", "虫族兵种", "人族兵种")
            private val arms = arrayOf(arrayOf("狂战士", "龙骑士", "黑暗圣堂", "电兵"),
                arrayOf("小狗", "刺蛇", "飞龙", "自爆飞机"),
                arrayOf("机枪兵", "护士MM", "幽灵"))
            private val textView: TextView
                get()
                {
                    val textView = TextView(this@MainActivity)
                    val lp = AbsListView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                        ViewGroup.LayoutParams.WRAP_CONTENT)
                    textView.layoutParams = lp
                    textView.gravity = Gravity.CENTER_VERTICAL or Gravity.START
                    textView.setPadding(36, 10, 0, 10)
                    textView.textSize = 20f
                    return textView
                }
            // 获取指定组位置、指定子列表项处的子列表项数据
            override fun getChild(groupPosition: Int, childPosition: Int): Any
            {
                return arms[groupPosition][childPosition]
            }

            override fun getChildId(groupPosition: Int, childPosition: Int): Long
            {
                return childPosition.toLong()
            }

            override fun getChildrenCount(groupPosition: Int): Int
            {
                return arms[groupPosition].size
            }

            // 该方法决定每个子选项的外观
            override fun getChildView(groupPosition: Int, childPosition: Int,
                                      isLastChild: Boolean, convertView: View?, parent: ViewGroup): View
            {
                val textView: TextView
                if (convertView == null)
                {
                    textView = this.textView
                    textView.text = getChild(groupPosition, childPosition).toString()
                }
                else
                {
                    textView = convertView as TextView
                }
                return textView
            }

            // 获取指定组位置处的组数据
            override fun getGroup(groupPosition: Int): Any
            {
                return armTypes[groupPosition]
            }

            override fun getGroupCount(): Int
            {
                return armTypes.size
            }

            override fun getGroupId(groupPosition: Int): Long
            {
                return groupPosition.toLong()
            }

            // 该方法决定每个组选项的外观
            override fun getGroupView(groupPosition: Int, isExpanded: Boolean,
                                      convertView: View?, parent: ViewGroup): View
            {
                val ll: LinearLayout
                if (convertView == null)
                {
                    ll = LinearLayout(this@MainActivity)
                    ll.orientation = LinearLayout.HORIZONTAL
                    val logo = ImageView(this@MainActivity)
                    logo.setImageResource(logos[groupPosition])
                    ll.addView(logo)
                    val textView = this.textView
                    textView.text = getGroup(groupPosition).toString()
                    ll.addView(textView)
                }
                else
                {
                    ll = convertView as LinearLayout
                }
                return ll
            }

            override fun isChildSelectable(groupPosition: Int, childPosition: Int): Boolean
            {
                return true
            }

            override fun hasStableIds(): Boolean
            {
                return true
            }
        }
        val expandListView = findViewById<ExpandableListView>(R.id.list)
        expandListView.setAdapter(adapter)
    }
}