ListView的item折叠功能实现，使用ExpandableListView

来酷狗面试的时候面试官问过我，如果要显示/隐藏ListView的某个Item项目中的某些内容，我会怎么做。

我当时的回答是，做一个布局文件里面把所有要用到的项目都写上，哪个不需要了就将他设为gone就可以了。

今天在看代码的时候发现，原来有ExpandableListView这个东西，很明显，我当时的回答有点太浅层次了。

ExpandableListView见名知意，专门用于实现可收缩的ListView，即其中的item有父子item。实现的效果大致如下，使用ExpandableListView来做父子Item实现起来相当容易。

ExpandableListView使用ExpandableListAdapter来做为其适配器，ExpandableListAdapter也有其基础适配器BaseExpandableListAdapter；

具体代码如下：

package com.wallj.listviewdemo;import android.R.color;import android.os.Bundle;import android.app.Activity;import android.view.View;import android.view.ViewGroup;import android.widget.BaseExpandableListAdapter;import android.widget.ExpandableListAdapter;import android.widget.ExpandableListView;import android.widget.TextView;public class ExpandableListViewDemo extends Activity {ExpandableListView mExpdListView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_expandable_list_view_demo);mExpdListView = (ExpandableListView) findViewById(R.id.exListView);mExpdListView.setAdapter(mExAdapter);}ExpandableListAdapter mExAdapter = new BaseExpandableListAdapter() {private String[] generalsTypes = new String[] { "魏", "蜀", "吴" };private String[][] generals = new String[][] {                { "夏侯惇", "甄姬", "许褚", "郭嘉", "司马懿", "杨修" },                { "马超", "张飞", "刘备", "诸葛亮", "黄月英", "赵云" },                { "吕蒙", "陆逊", "孙权", "周瑜", "孙尚香" }        };@Overridepublic boolean isChildSelectable(int arg0, int arg1) {return false;}@Overridepublic boolean hasStableIds() {return true;}@Overridepublic View getGroupView(int arg0, boolean arg1, View arg2, ViewGroup arg3) {if(arg2 == null){arg2 = new TextView(ExpandableListViewDemo.this);((TextView)arg2).setTextSize(30);}((TextView)arg2).setText(generalsTypes[arg0]);return arg2;}@Overridepublic long getGroupId(int arg0) {return arg0;}@Overridepublic int getGroupCount() {return generalsTypes.length;}@Overridepublic Object getGroup(int arg0) {return generalsTypes[arg0];}@Overridepublic int getChildrenCount(int arg0) {return generals[arg0].length;}@Overridepublic View getChildView(int arg0, int arg1, boolean arg2, View arg3,ViewGroup arg4) {if(arg3 == null){arg3 = new TextView(ExpandableListViewDemo.this);}((TextView)arg3).setText(generals[arg0][arg1]);return arg3;}@Overridepublic long getChildId(int arg0, int arg1) {return arg1;}@Overridepublic Object getChild(int arg0, int arg1) {return generals[arg0][arg1];}};}