android ExpandableListView详解

ExpandableListView是android中可以实现下拉list的一个控件，是一个垂直滚动的心事两个级别列表项手风琴试图，列表项是来自ExpandableListViewaAdapter，组可以单独展开。

重要方法：

 expandGroup (int groupPos) ;//在分组列表视图中 展开一组，
 setSelectedGroup (int groupPosition) ;//设置选择指定的组。

 setSelectedChild (int groupPosition, int childPosition, boolean shouldExpandGroup);//设置选择指定的子项。

 getPackedPositionGroup (long packedPosition);//返回所选择的组

 getPackedPositionForChild (int groupPosition, int childPosition) ;//返回所选择的子项

 getPackedPositionType (long packedPosition);//返回所选择项的类型（Child,Group）

 isGroupExpanded (int groupPosition);//判断此组是否展开

expandableListView.setDivider();这个是设定每个Group之间的分割线。

expandableListView.setGroupIndicator();这个是设定每个Group之前的那个图标。

expandableListView.collapseGroup(int group); 将第group组收起

ExpandableListAdapter

一个接口，将基础数据链接到一个ExpandableListView。 此接口的实施将提供访问Child的数据（由组分类），并实例化的Child和Group。

1.重要方法

　　　　getChildId (int groupPosition, int childPosition) 获取与在给定组给予孩子相关的数据。

　　　　getChildrenCount (int groupPosition) 返回在指定Group的Child数目。

案例：

首先定义个一个布局文件expandablelistview.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:orientation="vertical" >
      <ExpandableListView
         android:id ="@+id/expandableListView"
         android:layout_width ="fill_parent"
         android:layout_height ="wrap_content"
         >
      </ExpandableListView>
 </LinearLayout>

 package com.test;

 import java.util.ArrayList;
 import java.util.List;

 import javax.security.auth.PrivateCredentialPermission;

 import android.app.Activity;
 import android.os.Bundle;
 import android.view.Gravity;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.Window;
 import android.widget.AbsListView;
 import android.widget.BaseExpandableListAdapter;
 import android.widget.ExpandableListView;
 import android.widget.TextView;

 public class ExpandableListViewDemo extends Activity {
     /** Called when the activity is first created. */

     //定义两个List用来控制Group和Child中的String;

     private  List<String>  groupArray;//组列表
     private  List<List<String>> childArray;//子列表
     private  ExpandableListView  expandableListView_one;

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 //        requestWindowFeature(Window.FEATURE_NO_TITLE);  //设置为无标题
         setContentView(R.layout.expandablelistview);
         expandableListView_one =(ExpandableListView)findViewById(R.id.expandableListView);
         groupArray =new ArrayList<String>();
         childArray = new ArrayList<List<String>>();

         /*-第一季-*/
         initdate();
         expandableListView_one.setAdapter(new ExpandableListViewaAdapter(ExpandableListViewDemo.this));

         /*-第二季-*/
 //        groupArray.add("移动开发");
 //        List<String> arrayList = new ArrayList<String>();
 //        arrayList.add("Android");
 //        arrayList.add("IOS");
 //        arrayList.add("Windows Phone");
 //        //组循环
 //        for(int index=0;index<groupArray.size();++index)
 //        {
 //            childArray.add(arrayList);
 //        }
 //        expandableListView_one.setAdapter(new ExpandableListViewaAdapter(ExpandableListViewDemo.this));

     }
     class ExpandableListViewaAdapter extends BaseExpandableListAdapter {
         Activity activity;
          public  ExpandableListViewaAdapter(Activity a)
             {
                 activity = a;
             }
        /*-----------------Child */
         @Override
         public Object getChild(int groupPosition, int childPosition) {
             // TODO Auto-generated method stub
             return childArray.get(groupPosition).get(childPosition);
         }

         @Override
         public long getChildId(int groupPosition, int childPosition) {
             // TODO Auto-generated method stub
             return childPosition;
         }

         @Override
         public View getChildView(int groupPosition, int childPosition,
                 boolean isLastChild, View convertView, ViewGroup parent) {

             String string =childArray.get(groupPosition).get(childPosition);

             return getGenericView(string);
         }

         @Override
         public int getChildrenCount(int groupPosition) {
             // TODO Auto-generated method stub
             return childArray.get(groupPosition).size();
         }
        /* ----------------------------Group */
         @Override
         public Object getGroup(int groupPosition) {
             // TODO Auto-generated method stub
             return getGroup(groupPosition);
         }

         @Override
         public int getGroupCount() {
             // TODO Auto-generated method stub
             return groupArray.size();
         }

         @Override
         public long getGroupId(int groupPosition) {
             // TODO Auto-generated method stub
             return groupPosition;
         }

         @Override
         public View getGroupView(int groupPosition, boolean isExpanded,
                 View convertView, ViewGroup parent) {

            String   string=groupArray.get(groupPosition);
            return getGenericView(string);
         }

         @Override
         public boolean hasStableIds() {
             // TODO Auto-generated method stub
             return false;
         }

         @Override
         public boolean isChildSelectable(int groupPosition, int childPosition)
         {
             // TODO Auto-generated method stub
             return true;
         }

         private TextView  getGenericView(String string )
         {
               AbsListView.LayoutParams  layoutParams =new AbsListView.LayoutParams(
                     ViewGroup.LayoutParams.MATCH_PARENT,
                     ViewGroup.LayoutParams.WRAP_CONTENT);

               TextView  textView =new TextView(activity);
               textView.setLayoutParams(layoutParams);

               textView.setGravity(Gravity.CENTER_VERTICAL |Gravity.LEFT);

               textView.setPadding(40, 0, 0, 0);
               textView.setText(string);
               return textView;
          }
     }

     private void initdate()
     {
         addInfo("语言", new String[]{"Oracle","Java","Linux","Jquery"});
         addInfo("男人的需求", new String[]{"金钱","事业","权力","女人","房子","车","球"});
     }
     private void addInfo(String group,String []child) {

         groupArray.add(group);

         List<String>  childItem =new ArrayList<String>();

         for(int index=0;index<child.length;index++)
         {
             childItem.add(child[index]);
         }
          childArray.add(childItem);
     }
 }