由于工作需要，今天简单研究了一下ExpandableListView，做了一个类似QQ列表的Demo，和大家分享一下。
效果图如下：
先来看看主布局文件：
<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"
android:background="#EDEDED"
tools:context="com.example.expandablelistview.MainActivity" >
<ExpandableListView
android:id="@+id/my_listview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="10dp"
android:divider="@null"
android:dividerHeight="8dip" >
</ExpandableListView>
</RelativeLayout>这里我们不使用系统默认的分隔线，两个组之间的距离为8dp.
对于ExpandableListView，系统为我们提供了专门的适配器BaseExpandableListAdapter，我们可以自定义一个适配器继承BaseExpandableListAdapter，实现该类中的一些方法即可。
代码如下：
public class MyAdapter extends BaseExpandableListAdapter {
private List<GroupBean> list;
private Context context;
public MyAdapter(List<GroupBean> list, Context context) {
this.list = list;
this.context = context;
}
public MyAdapter() {
}
@Override
public int getGroupCount() {
return list.size();
}
@Override
public int getChildrenCount(int groupPosition) {
return list.get(groupPosition).getChildren().size();
}
@Override
public Object getGroup(int groupPosition) {
return list.get(groupPosition);
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return list.get(groupPosition).getChildren().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 false;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
GroupHolder holder;
if (convertView == null) {
holder = new GroupHolder();
convertView = LayoutInflater.from(context).inflate(
R.layout.item_group, null);
holder.title = (TextView) convertView
.findViewById(R.id.group_title);
holder.iv = (ImageView) convertView.findViewById(R.id.group_ico);
convertView.setTag(holder);
} else {
holder = (GroupHolder) convertView.getTag();
}
holder.title.setText(list.get(groupPosition).getGroupName());
if (isExpanded) {
holder.iv.setImageResource(R.drawable.rounds_open);
} else {
holder.iv.setImageResource(R.drawable.rounds_close);
}
return convertView;
}
@Override
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
ChildHolder holder;
if (convertView == null) {
holder = new ChildHolder();
convertView = LayoutInflater.from(context).inflate(
R.layout.item_child, null);
holder.name = (TextView) convertView.findViewById(R.id.child_name);
holder.sign = (TextView) convertView.findViewById(R.id.child_sign);
convertView.setTag(holder);
} else {
holder = (ChildHolder) convertView.getTag();
}
ChildBean cb = list.get(groupPosition).getChildren().get(childPosition);
holder.name.setText(cb.getName());
holder.sign.setText("[签名]"+cb.getSign());
return convertView;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return false;
}
class GroupHolder {
TextView title;
ImageView iv;
}
class ChildHolder {
TextView name, sign;
}
}这里的代码有点长，我们稍微解释一下，先是构造方法中传入两个参数，一个是数据源list，另外一个是上下文，list是一个GroupBean集合，GroupBean如下：
public class GroupBean {
private String groupName;
private List<ChildBean> children;
public String getGroupName() {
return groupName;
}
public void setGroupName(String groupName) {
this.groupName = groupName;
}
public List<ChildBean> getChildren() {
return children;
}
public void setChildren(List<ChildBean> children) {
this.children = children;
}
public GroupBean(String groupName, List<ChildBean> children) {
this.groupName = groupName;
this.children = children;
}
public GroupBean() {
}
}很明显，GroupBean有两个属性，一个是组名字，另外一个是该组下子项的一个集合，这个ChildBean就是每个组下面的每一个对象的数据，ChildBean代码如下：
public class ChildBean {
private String name;
private String sign;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSign() {
return sign;
}
public void setSign(String sign) {
this.sign = sign;
}
public ChildBean(String name, String sign) {
this.name = name;
this.sign = sign;
}
public ChildBean() {
}
}说完list，下面就是getGroupCount()和getChildrenCount(),这个有点类似于我们使用BaseAdapter时的getCount(),不同的是这里分别要返回每个组的数量，以及组内成员的数量，那么组的数量当然就是list.size()，组内成员的数量由于每组不同，所以要先拿到每个组，再拿到该组里成员的数量，代码就是list.get(groupPosition).getChildren().size();。接下来的两个方法就是getGroup()和getChild(),这个类似于BaseAdapter中的getItem，我们返回的时候还是组和组内的子项分开返回，代码很简单，就不多说了。稍微长一点的方法就是getGroupView和getChildView，不多也都没啥逻辑，和我们在ListView中使用BaseAdapter中的getView方法差不多，不同的是数据赋值的时候有差别。
我个人觉得，使用ExpandableListView关键在于把数据结构搞清楚，Group和Child搞清楚了，其他的都很简单。
这里我把Group的布局和Child的布局贴出来给大家看看：
item_group.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="48dp"
android:background="@drawable/item_background_select" >
<TextView
android:id="@+id/group_title"
android:layout_width="wrap_content"
android:layout_height="48dp"
android:layout_marginLeft="36dp"
android:gravity="center"
android:text="好友分组"
android:textSize="18sp" />
<ImageView
android:id="@+id/group_ico"
android:layout_width="24dip"
android:layout_height="24dip"
android:layout_alignParentRight="true"
android:layout_marginBottom="12dp"
android:layout_marginLeft="24dp"
android:layout_marginRight="24dp"
android:layout_marginTop="12dp"
android:scaleType="centerInside"
android:src="@drawable/rounds_close" />
<TextView
android:id="@+id/split_lines"
android:layout_width="1dip"
android:layout_height="48dp"
android:layout_toLeftOf="@id/group_ico"
android:background="#E6E6E6" />
</RelativeLayout>item_child.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="36dp"
android:orientation="vertical" >
<TextView
android:id="@+id/child_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="10dip"
android:text="姓名"
android:textSize="18sp" />
<TextView
android:id="@+id/child_sign"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/child_name"
android:paddingLeft="10dip"
android:paddingRight="10dip"
android:text="签名"
android:textSize="12sp" />
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#B2DFEE" />
</RelativeLayout>这里还涉及到一个圆角方框，代码是这样的：
item_background_select.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
<corners android:radius="8dip" />
<solid android:color="#FFFFFFFF" />
</shape>好了，所有的准备工作都已经完成，下面看看怎么使用
public class MainActivity extends Activity {
private ExpandableListView mListView;
private MyAdapter adapter;
private List<GroupBean> list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化数据
initData();
mListView = (ExpandableListView) this.findViewById(R.id.my_listview);
adapter = new MyAdapter(list, this);
mListView.setAdapter(adapter);
mListView.setGroupIndicator(null);
// mListView.expandGroup(0);
}
private void initData() {
list = new ArrayList<GroupBean>();
{
List<ChildBean> list1 = new ArrayList<ChildBean>();
ChildBean cb1 = new ChildBean("妈妈", "123");
ChildBean cb2 = new ChildBean("爸爸", "456");
ChildBean cb3 = new ChildBean("爷爷", "789");
ChildBean cb4 = new ChildBean("妹妹", "000");
list1.add(cb1);
list1.add(cb2);
list1.add(cb3);
list1.add(cb4);
GroupBean gb1 = new GroupBean("家", list1);
list.add(gb1);
}
{
List<ChildBean> list1 = new ArrayList<ChildBean>();
ChildBean cb1 = new ChildBean("张三", "123");
ChildBean cb2 = new ChildBean("李四", "456");
ChildBean cb3 = new ChildBean("王五", "789");
ChildBean cb4 = new ChildBean("赵六", "000");
ChildBean cb5 = new ChildBean("风起", "1111");
ChildBean cb6 = new ChildBean("马坝", "222");
ChildBean cb7 = new ChildBean("迁就", "3333333");
list1.add(cb1);
list1.add(cb2);
list1.add(cb3);
list1.add(cb4);
list1.add(cb5);
list1.add(cb6);
list1.add(cb7);
GroupBean gb1 = new GroupBean("我的朋友", list1);
list.add(gb1);
}
{
List<ChildBean> list1 = new ArrayList<ChildBean>();
ChildBean cb1 = new ChildBean("Tom", "123");
ChildBean cb2 = new ChildBean("Jerry", "456");
ChildBean cb4 = new ChildBean("Bush", "000");
list1.add(cb1);
list1.add(cb2);
list1.add(cb4);
GroupBean gb1 = new GroupBean("国际友人", list1);
list.add(gb1);
}
{
List<ChildBean> list1 = new ArrayList<ChildBean>();
ChildBean cb1 = new ChildBean("赵工", "123");
ChildBean cb2 = new ChildBean("马工", "456");
ChildBean cb3 = new ChildBean("王工", "789");
ChildBean cb4 = new ChildBean("李工", "000");
ChildBean cb5 = new ChildBean("为工", "000");
list1.add(cb1);
list1.add(cb2);
list1.add(cb3);
list1.add(cb4);
list1.add(cb5);
GroupBean gb1 = new GroupBean("同事", list1);
list.add(gb1);
}
}
}这里有两行代码我稍微说一下mListView.setGroupIndicator(null);表示不使用系统提供的展开和收起的图标，mListView.expandGroup(0);表示默认打开第一项。
好了，就说这些，有问题欢迎留言讨论。
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