Android常用控件之ExpandableList的使用

先来看下什么是ExpandableListView

跟列表有点像，这种是可以折叠的列表，下面来看下是如何在代码中实现

一、在布局文件中声明一个ExpandableListView

<LinearLayout 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/android:list"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:drawSelectorOnTop="false" >
    </ExpandableListView>

    <TextView
        android:id="@id/android:empty"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/no_data" />

</LinearLayout>

二、为每个Group和Child定义一个布局

group.xml

<?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/groupTo"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:paddingLeft="50dp"
        android:paddingTop="5dp"
        android:paddingBottom="5dp"
        android:textSize="20sp"
        android:text="@string/no_data"/>
</LinearLayout>

child.xml

<?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/childTo"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:paddingLeft="60dp"
        android:paddingTop="10dp"
        android:paddingBottom="10dp"
        android:textSize="20sp"
        android:text="@string/no_data"/>
</LinearLayout>

以上两个文件只有缩进不一样，这样可以明显区分Group和Child

三、在代码中实现

package com.example.expandableList;

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

import android.app.ExpandableListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.SimpleExpandableListAdapter;
import android.widget.Toast;

import com.example.widgetdemo.R;

public class expandableList extends ExpandableListActivity {
	ExpandableListView expandableList = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.expandable);

		expandableList = getExpandableListView();

		// 写入当前组数
		List<Map<String, String>> groups = new ArrayList<Map<String, String>>();
		Map<String, String> group1 = new HashMap<String, String>();
		group1.put("group", "广东省");
		Map<String, String> group2 = new HashMap<String, String>();
		group2.put("group", "江西省");
		groups.add(group1);
		groups.add(group2);

		// 写入第一组的数据
		List<Map<String, String>> child1 = new ArrayList<Map<String, String>>();
		Map<String, String> childData1 = new HashMap<String, String>();
		childData1.put("child", "广州市");
		Map<String, String> childData2 = new HashMap<String, String>();
		childData2.put("child", "深圳市");
		Map<String, String> childData3 = new HashMap<String, String>();
		childData3.put("child", "东莞市");
		child1.add(childData1);
		child1.add(childData2);
		child1.add(childData3);
		// 写入第二组的数据
		List<Map<String, String>> child2 = new ArrayList<Map<String, String>>();
		Map<String, String> childData4 = new HashMap<String, String>();
		childData4.put("child", "赣州市");
		Map<String, String> childData5 = new HashMap<String, String>();
		childData5.put("child", "南昌市");
		Map<String, String> childData6 = new HashMap<String, String>();
		childData6.put("child", "九江市");
		Map<String, String> childData7 = new HashMap<String, String>();
		childData7.put("child", "吉安市");
		child2.add(childData4);
		child2.add(childData5);
		child2.add(childData6);
		child2.add(childData7);

		List<List<Map<String, String>>> childs = new ArrayList<List<Map<String, String>>>();
		childs.add(child1);
		childs.add(child2);

		SimpleExpandableListAdapter sela = new SimpleExpandableListAdapter(
				expandableList.this, groups, R.layout.group,
				new String[] { "group" }, new int[] { R.id.groupTo }, childs,
				R.layout.child, new String[] { "child" },
				new int[] { R.id.childTo });
		setListAdapter(sela);
		expandableList.setOnChildClickListener(new expandableListListener());
	}

	//为ExpandableListView编写监听器
	class expandableListListener implements OnChildClickListener {

		@Override
		public boolean onChildClick(ExpandableListView parent, View v,
				int groupPosition, int childPosition, long id) {
			// TODO Auto-generated method stub
			System.out.println("group = " + groupPosition + " child = "
					+ childPosition + " id = " + id);

			ExpandableListAdapter exAdapter = parent.getExpandableListAdapter();

			// 获得选中项的HashMap对象
			Map<String, String> childMap = (HashMap<String, String>) exAdapter
					.getChild(groupPosition, childPosition);
			String contentChild = childMap.get("child");
			Map<String, String> groupMap = (HashMap<String, String>) exAdapter
					.getGroup(groupPosition);
			String contentGroup = groupMap.get("group");
			Toast.makeText(
					getApplicationContext(),
					"你选择了第" + groupPosition + " 个Group， 第 " + childPosition
							+ " 个Child的值是：" + contentChild + " Group的值是 " + contentGroup,
					Toast.LENGTH_LONG).show();
			return false;
		}

	}
}

关于如何获取选中的值，我查看文档终于找到ExpandableListAdapter，在这个适配器有获取那个child和group的方法。

下面看下效果

最后还是传上源码

点击打开链接