android ExpandableListView简单例子

   android中常常要用到ListView，有时也要用到ExpandableListView，如在手机设置中，对于分类有很好的效果，会用ListView的人一定会用ExpandableListView，因为
 ExpandableListView extends ListView的，下面来看个简单的例子
 
 运行效果图：
 

<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/expendlist"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
    </ExpandableListView>

 </RelativeLayout>

 //扩展ListView的头List布局文件
 <?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="wrap_content"
  android:orientation="horizontal" >

  <TextView
   android:id="@+id/txt"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content" />

  <ImageView
   android:id="@+id/img"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content" />
 </LinearLayout>

 //扩展ListView的子List布局文件
 <?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="horizontal"
  android:padding="10.0dp" >

  <ImageView
   android:id="@+id/img"
   android:layout_width="20.0dp"
   android:layout_height="20.0dp" />

  <TextView
   android:id="@+id/txt"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content" />

 </LinearLayout>

package com.example.test;

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

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

 public class MainActivity extends Activity {

 private ExpandableListView expandableListView;
 private List<String> group_list;
 private List<List<String>> item_list;
 private List<List<Integer>> item_list2;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  //随便一堆测试数据
  group_list = new ArrayList<String>();
  group_list.add("A");
  group_list.add("B");
  group_list.add("C");

  item_list = new ArrayList<List<String>>();
  item_list.add(group_list);
  item_list.add(group_list);
  item_list.add(group_list);

  List<Integer> tmp_list = new ArrayList<Integer>();
  tmp_list.add(R.drawable.ic_launcher);
  tmp_list.add(R.drawable.ic_launcher);
  tmp_list.add(R.drawable.ic_launcher);

  item_list2 = new ArrayList<List<Integer>>();
  item_list2.add(tmp_list);
  item_list2.add(tmp_list);
  item_list2.add(tmp_list);

  expandableListView = (ExpandableListView) findViewById(R.id.expendlist);
  expandableListView.setAdapter(new MyExpandableListViewAdapter(this));
 }

 //用过ListView的人一定很熟悉，只不过这里是BaseExpandableListAdapter
 class MyExpandableListViewAdapter extends BaseExpandableListAdapter {

  private Context context;

  public MyExpandableListViewAdapter(Context context) {
   this.context = context;
  }

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

  @Override
  public int getChildrenCount(int groupPosition) {
   return item_list.get(groupPosition).size();
  }

  @Override
  public Object getGroup(int groupPosition) {
   return group_list.get(groupPosition);
  }

  @Override
  public Object getChild(int groupPosition, int childPosition) {
   return item_list.get(groupPosition).get(childPosition);
  }

  @Override
  public long getGroupId(int groupPosition) {
   return groupPosition;
  }

  @Override
  public long getChildId(int groupPosition, int childPosition) {
   return childPosition;
  }

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

  @Override
  public View getGroupView(int groupPosition, boolean isExpanded,
    View convertView, ViewGroup parent) {
   GroupHolder groupHolder = null;
   if (convertView == null) {
    convertView = (View) getLayoutInflater().from(context).inflate(
      R.layout.expendlist_group, null);
    groupHolder = new GroupHolder();
    groupHolder.txt = (TextView) convertView.findViewById(R.id.txt);
    // groupHolder.img = (ImageView) convertView
    // .findViewById(R.id.img);
    convertView.setTag(groupHolder);
   } else {
    groupHolder = (GroupHolder) convertView.getTag();
   }
   groupHolder.txt.setText(group_list.get(groupPosition));
   return convertView;
  }

  @Override
  public View getChildView(int groupPosition, int childPosition,
    boolean isLastChild, View convertView, ViewGroup parent) {
   ItemHolder itemHolder = null;
   if (convertView == null) {
    convertView = (View) getLayoutInflater().from(context).inflate(
      R.layout.expendlist_item, null);
    itemHolder = new ItemHolder();
    itemHolder.txt = (TextView) convertView.findViewById(R.id.txt);
    itemHolder.img = (ImageView) convertView.findViewById(R.id.img);
    convertView.setTag(itemHolder);
   } else {
    itemHolder = (ItemHolder) convertView.getTag();
   }
   itemHolder.txt.setText(item_list.get(groupPosition).get(
     childPosition));
   itemHolder.img.setBackgroundResource(item_list2.get(groupPosition).get(
     childPosition));
   return convertView;
  }

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

 }

 class GroupHolder {
  public TextView txt;
  public ImageView img;
 }

 class ItemHolder {
  public ImageView img;
  public TextView txt;
 }
}

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