在网上看到一个例子，讲android中的expandablelistview，是一种可以扩展的listview，就是那种点击一下可以扩展出子项，再点一下收缩回去的显示list。因为需要查看一堆文件的目录结构，就使用了expandablelist以便于直观地看到结构形式。
顶层是group，第二层是child。实现ExpandableListView至少需要下面两个类。
一、ExpandableListView
一个垂直滚动的显示两个级别（Child,Group）列表项的视图，列表项来自ExpandableListAdapter 。组可以单独展开。
其所用到的重要方法如下：
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
二、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。
其里面重要方法：
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。
getChildView() 获取子视图（就是二级视图）
getChildView()获取父视图
当我们想做到自己的打开或者关闭的标记时，可以先设置一个selector.xml，然后再用ExpandableListView的实例去调用setGroupIndicator(this.getResources().getDrawable(R.drawable.expand_list_selector)); 这样就可以了。
下面就看下例子：
这个代码好像也是在eoe上下载下来的，具体也记不太清楚了，先看下效果图：
先给下代码，人家写的，咱们学习下：
public class ListViewActivity extends Activity
{
ExpandableListView expandableListView;
ListViewAdapter treeViewAdapter;
public String[] groups = { "列表1", "列表2", "列表3" };
public String[][] child = { { "" }, { "" }, { "", "" } };
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
treeViewAdapter = new ListViewAdapter(this,
ListViewAdapter.PaddingLeft >> 1);
expandableListView = (ExpandableListView) this
.findViewById(R.id.expandableListView);
List<ListViewAdapter.TreeNode> treeNode = treeViewAdapter.GetTreeNode();
for (int i = 0; i < groups.length; i++)
{
ListViewAdapter.TreeNode node = new ListViewAdapter.TreeNode();
node.parent = groups[i];
for (int ii = 0; ii < child[i].length; ii++)
{
node.childs.add(child[i][ii]);
}
treeNode.add(node);
}
treeViewAdapter.UpdateTreeNode(treeNode);
expandableListView.setAdapter(treeViewAdapter);
}
}
GridView的定义：
class MyGridView extends GridView { public MyGridView(android.content.Context context, android.util.AttributeSet attrs) { super(context, attrs); } /** * 设置不滚动 */ public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST); super.onMeasure(widthMeasureSpec, expandSpec); } }
adapter的代码：
public class ListViewAdapter extends BaseExpandableListAdapter implements
OnItemClickListener
{
public static final int ItemHeight = 48;// 每项的高度
public static final int PaddingLeft = 36;// 每项的高度
private int myPaddingLeft = 0;
private MyGridView toolbarGrid;
private String menu_toolbar_name_array[] = { "存储卡", "我的下载", "图书导入", "系统备份",
"系统恢复", "清除全部", "在线升级", "快速入门", "关于开卷", "退出系统", "在线升级", "快速入门",
"关于开卷", "退出系统", "关于开卷", "退出系统", "关于开卷", "退出系统", "关于开卷", "退出系统" };
private int menu_toolbar_image_array[] = { R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard, R.drawable.icon_sdcard,
R.drawable.icon_sdcard };
private List<TreeNode> treeNodes = new ArrayList<TreeNode>();
private Context parentContext;
private LayoutInflater layoutInflater;
static public class TreeNode
{
Object parent;
List<Object> childs = new ArrayList<Object>();
}
public ListViewAdapter(Context view, int myPaddingLeft)
{
parentContext = view;
this.myPaddingLeft = myPaddingLeft;
}
public List<TreeNode> GetTreeNode()
{
return treeNodes;
}
public void UpdateTreeNode(List<TreeNode> nodes)
{
treeNodes = nodes;
}
public void RemoveAll()
{
treeNodes.clear();
}
public Object getChild(int groupPosition, int childPosition)
{
return treeNodes.get(groupPosition).childs.get(childPosition);
}
public int getChildrenCount(int groupPosition)
{
return treeNodes.get(groupPosition).childs.size();
}
static public TextView getTextView(Context context)
{
AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT, ItemHeight);
TextView textView = new TextView(context);
textView.setLayoutParams(lp);
textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
return textView;
}
/**
* 可自定义ExpandableListView
*/
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent)
{
if (convertView == null)
{
layoutInflater = (LayoutInflater) parentContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = layoutInflater.inflate(R.layout.view, null);
toolbarGrid = (MyGridView) convertView
.findViewById(R.id.GridView_toolbar);
toolbarGrid.setNumColumns(4);// 设置每行列数
toolbarGrid.setGravity(Gravity.CENTER);// 位置居中
toolbarGrid.setHorizontalSpacing(10);// 水平间隔
toolbarGrid.setAdapter(getMenuAdapter(menu_toolbar_name_array,
menu_toolbar_image_array));// 设置菜单Adapter
toolbarGrid.setOnItemClickListener(this);
}
return convertView;
}
/**
* 可自定义list
*/
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent)
{
TextView textView = getTextView(this.parentContext);
textView.setText(getGroup(groupPosition).toString());
textView.setPadding(myPaddingLeft + PaddingLeft, 0, 0, 0);
return textView;
}
public long getChildId(int groupPosition, int childPosition)
{
return childPosition;
}
public Object getGroup(int groupPosition)
{
return treeNodes.get(groupPosition).parent;
}
public int getGroupCount()
{
return treeNodes.size();
}
public long getGroupId(int groupPosition)
{
return groupPosition;
}
public boolean isChildSelectable(int groupPosition, int childPosition)
{
return true;
}
public boolean hasStableIds()
{
return true;
}
/**
* 构造菜单Adapter
*
* @param menuNameArray
* 名称
* @param imageResourceArray
* 图片
* @return SimpleAdapter
*/
private SimpleAdapter getMenuAdapter(String[] menuNameArray,
int[] imageResourceArray)
{
ArrayList<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>();
for (int i = 0; i < menuNameArray.length; i++)
{
HashMap<String, Object> map = new HashMap<String, Object>();
map.put("itemImage", imageResourceArray[i]);
map.put("itemText", menuNameArray[i]);
data.add(map);
}
SimpleAdapter simperAdapter = new SimpleAdapter(parentContext, data,
R.layout.item_menu, new String[] { "itemImage", "itemText" },
new int[] { R.id.item_image, R.id.item_text });
return simperAdapter;
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id)
{
Toast.makeText(parentContext, "当前选中的是:" + position, Toast.LENGTH_SHORT)
.show();
}
}
里面比较简单的是listView，比较难的就是嵌套GridView吧!
定义文字和图片：
private String menu_toolbar_name_array[] = { "存储卡", "我的下载", "图书导入", "系统备份", "系统恢复", "清除全部", "在线升级", "快速入门", "关于开卷", "退出系统", "在线升级", "快速入门", "关于开卷", "退出系统", "关于开卷", "退出系统", "关于开卷", "退出系统", "关于开卷", "退出系统" }; private int menu_toolbar_image_array[] = { R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard, R.drawable.icon_sdcard };
里面很重要的是那个node,一定要看理解：
public List<TreeNode> GetTreeNode()
{
return treeNodes;
}
public void UpdateTreeNode(List<TreeNode> nodes)
{
treeNodes = nodes;
}
public void RemoveAll()
{
treeNodes.clear();
}
public Object getChild(int groupPosition, int childPosition)
{
return treeNodes.get(groupPosition).childs.get(childPosition);
}
public int getChildrenCount(int groupPosition)
{
return treeNodes.get(groupPosition).childs.size();
}
public Object getGroup(int groupPosition)
{
return treeNodes.get(groupPosition).parent;
}
public int getGroupCount()
{
return treeNodes.size();
}
adapter也挺简单：
private SimpleAdapter getMenuAdapter(String[] menuNameArray,
int[] imageResourceArray)
{
ArrayList<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>();
for (int i = 0; i < menuNameArray.length; i++)
{
HashMap<String, Object> map = new HashMap<String, Object>();
map.put("itemImage", imageResourceArray[i]);
map.put("itemText", menuNameArray[i]);
data.add(map);
}
SimpleAdapter simperAdapter = new SimpleAdapter(parentContext, data,
R.layout.item_menu, new String[] { "itemImage", "itemText" },
new int[] { R.id.item_image, R.id.item_text });
return simperAdapter;
}
