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);
    }
}