<?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>

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)

    }

}