ExpandableListView的用法

ExpandableListView组件是android中一个比较常用的组件，当点击一个父item的时候可以将它的子item显示出来，像手机QQ中的好友列表就是实现的类型效果。使用ExpandableListView组件的关键就是设置它的adapter，这个adapter必须继承BaseExpandbaleListAdapter类，所以实现运用ExpandableListView的核心就是学会继承这个BaseExpanableListAdapter类。

下面是一个小demo：

activvity_main.xml:

 <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"
     tools:context=".MainActivity" >

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

 </RelativeLayout>

layout_parent.xml:(父item运用的样式)

 <?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="match_parent"
     android:orientation="vertical" >

     <TextView
         android:id="@+id/parent_textview"
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:layout_gravity="center"
         android:gravity="center" />

 </LinearLayout>

layout_children.xml:(子item运用的样式)

 <?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="match_parent"
     android:orientation="vertical" >

     <TextView
         android:id="@+id/second_textview"
         android:layout_width="match_parent"
         android:layout_height="40dp"
         android:layout_gravity="center"
         android:gravity="center" />

 </LinearLayout>

MainActivity.java:

 package com.example.android_expandablelistview;

 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 import android.app.Activity;
 import android.content.Context;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.BaseExpandableListAdapter;
 import android.widget.ExpandableListView;
 import android.widget.TextView;

 public class MainActivity extends Activity {

     ExpandableListView mainlistview = null;
     List<String> parent = null;
     Map<String, List<String>> map = null;

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

         initData();
         mainlistview.setAdapter(new MyAdapter());
     }

     // 初始化数据
     public void initData() {
         parent = new ArrayList<String>();
         parent.add("parent1");
         parent.add("parent2");
         parent.add("parent3");

         map = new HashMap<String, List<String>>();

         List<String> list1 = new ArrayList<String>();
         list1.add("child1-1");
         list1.add("child1-2");
         list1.add("child1-3");
         map.put("parent1", list1);

         List<String> list2 = new ArrayList<String>();
         list2.add("child2-1");
         list2.add("child2-2");
         list2.add("child2-3");
         map.put("parent2", list2);

         List<String> list3 = new ArrayList<String>();
         list3.add("child3-1");
         list3.add("child3-2");
         list3.add("child3-3");
         map.put("parent3", list3);

     }

     class MyAdapter extends BaseExpandableListAdapter {

         //得到子item需要关联的数据
         @Override
         public Object getChild(int groupPosition, int childPosition) {
             String key = parent.get(groupPosition);
             return (map.get(key).get(childPosition));
         }

         //得到子item的ID
         @Override
         public long getChildId(int groupPosition, int childPosition) {
             return childPosition;
         }

         //设置子item的组件
         @Override
         public View getChildView(int groupPosition, int childPosition,
                 boolean isLastChild, View convertView, ViewGroup parent) {
             String key = MainActivity.this.parent.get(groupPosition);
             String info = map.get(key).get(childPosition);
             if (convertView == null) {
                 LayoutInflater inflater = (LayoutInflater) MainActivity.this
                         .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                 convertView = inflater.inflate(R.layout.layout_children, null);
             }
             TextView tv = (TextView) convertView
                     .findViewById(R.id.second_textview);
             tv.setText(info);
             return tv;
         }

         //获取当前父item下的子item的个数
         @Override
         public int getChildrenCount(int groupPosition) {
             String key = parent.get(groupPosition);
             int size=map.get(key).size();
             return size;
         }
       //获取当前父item的数据
         @Override
         public Object getGroup(int groupPosition) {
             return parent.get(groupPosition);
         }

         @Override
         public int getGroupCount() {
             return parent.size();
         }

         @Override
         public long getGroupId(int groupPosition) {
             return groupPosition;
         }
        //设置父item组件
         @Override
         public View getGroupView(int groupPosition, boolean isExpanded,
                 View convertView, ViewGroup parent) {
             if (convertView == null) {
                 LayoutInflater inflater = (LayoutInflater) MainActivity.this
                         .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                 convertView = inflater.inflate(R.layout.layout_parent, null);
             }
             TextView tv = (TextView) convertView
                     .findViewById(R.id.parent_textview);
             tv.setText(MainActivity.this.parent.get(groupPosition));
             return tv;
         }

         @Override
         public boolean hasStableIds() {
             return true;
         }

         @Override
         public boolean isChildSelectable(int groupPosition, int childPosition) {
             return true;
         }

     }
 }

最后的实现结果：