ExpandableListView组件中CheckBox全选的使用（使用观察者模式）

ExpandableListView组件类似于手机QQ的好友分组组件，点击分组可展开显示分组下的子数据，很多时候我们会利用ExpandableListView实现子数据选中以及分组钟全部数据选中的功能，本篇博客就是介绍该功能的实现，以及观察者模式的使用。

首先看下实现截图：



然后贴下Activity代码：

package com.example.observer;

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

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.TextView;

import com.example.testdemo.R;

/**
* 观察者模式实现 ExpandableListView 的全选功能
* @author yhw
*
*/
public class ObserverActivity extends Activity implements OnChildClickListener{
private ExpandableListView expandableListView;
private ExpandAdapter expandAdapter;
private List<Group>groups;
private TextView textView;  //显示选中对象的view
private StringBuffer buffer;

private List<Object> selecteds=new ArrayList<Object>(); //存放选中对象的集合

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

expandableListView=(ExpandableListView) findViewById(R.id.expandablelistview);
textView=(TextView)findViewById(R.id.selectedview);
expandableListView.setOnChildClickListener(this);
buffer=new StringBuffer();
showData();
}

private final static String provinces[]={"陕西省","内蒙古","山西省","辽宁省"};
private final static String citys[][]={{"西安市","咸阳市","汉中市","榆林市","延安市"}
,{"呼和浩特","锡林郭勒","巴彦淖尔","鄂尔多斯"}
,{"太原市","吕梁市","大同市"}
,{"沈阳市","大连市"}};

private void showData(){
groups=new ArrayList<Group>();

for (int i = 0; i < provinces.length; i++) {
Group group=new Group();
group.setGroupName(provinces[i]);
group.setSelected(false);
List<Child> childs=new ArrayList<Child>();
for (int j = 0; j < citys[i].length; j++) {
Child child=new Child();
child.setSelected(false);
child.setChildName(citys[i][j]);
childs.add(child);

child.addObserver(group);
group.addObserver(child);
}
group.setChilds(childs);
groups.add(group);
}

if(expandAdapter==null){
expandAdapter=new ExpandAdapter(this, groups);
expandableListView.setAdapter(expandAdapter);
}else{
expandAdapter.notifyDataSetChanged();
}
}

@Override
public boolean onChildClick(ExpandableListView parent, View v,
int groupPosition, int childPosition, long id) {
Child child=groups.get(groupPosition).getChilds().get(childPosition);
child.changeChecked();
showSelected();
expandAdapter.notifyDataSetChanged();
return false;
}

/**显示选中的数据*/
public void showSelected(){
//清除
selecteds.clear();
buffer.delete(0, buffer.length());

for (Group group: groups) {
if(group.isSelected()){
selecteds.add(group);
}else{
for (Child child : group.getChilds()) {
if(child.isSelected()){
selecteds.add(child);
}
}
}
}

if(selecteds.size()>0){
for (Object  object : selecteds) {
if(object instanceof Group){
buffer.append(((Group)object).getGroupName()+"[组]、");
}
if(object instanceof Child){
buffer.append(((Child)object).getChildName()+"、");
}
}
textView.setText(buffer.toString());
}
}

}

布局文件xml代码：

<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"
android:padding="5dp"
android:orientation="vertical"
tools:context="com.example.observer.ObserverActivity" >

<TextView
android:id="@+id/selectedview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="16sp"/>

<ExpandableListView
android:id="@+id/expandablelistview"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:layout_marginTop="10dp"
android:groupIndicator="@null"/>

</LinearLayout>


最后是两个实体类的代码（两个实体类本身即属于观察者，又同时属于被观察者）：

分组实体需要继承Observable类和实现Observer接口

package com.example.observer;

import java.util.List;
import java.util.Observable;
import java.util.Observer;

import android.util.Log;

public class Group extends Observable implements Observer{

private String groupName;
private List<Child> childs;
private boolean isSelected;

public String getGroupName() {
return groupName;
}

public void setGroupName(String groupName) {
this.groupName = groupName;
}

public List<Child> getChilds() {
return childs;
}

public void setChilds(List<Child> childs) {
this.childs = childs;
}

public boolean isSelected() {
return isSelected;
}

public void setSelected(boolean isSelected) {
this.isSelected = isSelected;
}

public void changeChecked(){
isSelected=!isSelected;
setChanged();
notifyObservers(isSelected);
}

@Override
public void update(Observable observable, Object data) {
Log.i("YHW", "group update");
boolean flag=true;
for (Child child: childs) {
if(!child.isSelected()){
flag=false;
}
}
isSelected=flag;
}

}

子数据实体需要继承Observable类和实现Observer接口
<span style="color:#333333;">package com.example.observer;

import java.util.Observable;
import java.util.Observer;

import android.util.Log;

public class Child extends Observable implements Observer{

private String childName;
private boolean isSelected;

public String getChildName() {
return childName;
}

public void setChildName(String childName) {
this.childName = childName;
}

public boolean isSelected() {
return isSelected;
}

public void setSelected(boolean isSelected) {
this.isSelected = isSelected;
}

public void changeChecked(){
isSelected=!isSelected;
setChanged();
notifyObservers();
}

@Override
public void update(Observable observable,
968a
Object data) {
Log.i("YHW", "child update");
if(data instanceof Boolean){
isSelected=(Boolean) data;
}
}

}</span><span style="color:#ff0000;">
</span>

总结：
总体实现比较简单，就不做过多阐述了，主要就是通过观察者模式，实现分组数据和子数据之间互相监听选中与否