Android中级联列表ExpandableListView使用

     最近需要用到级联操作，一级菜单和二级菜单的显示，发现Android官方自带了一个控件，ExpandableListView，学了一下用法，还好比较简单，当然也要先写一个自定义的适配器去继承BaseExpandableListAdapter，并实现方法

public class MyAdapter extends BaseExpandableListAdapter{

	@Override
	public int getGroupCount() {
		return 0;
	}

	@Override
	public int getChildrenCount(int groupPosition) {
		return 0;
	}

	@Override
	public Object getGroup(int groupPosition) {
		return null;
	}

	@Override
	public Object getChild(int groupPosition, int childPosition) {
		return null;
	}

	@Override
	public long getGroupId(int groupPosition) {
		return 0;
	}

	@Override
	public long getChildId(int groupPosition, int childPosition) {
		return 0;
	}

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

	@Override
	public View getGroupView(int groupPosition, boolean isExpanded,
			View convertView, ViewGroup parent) {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public View getChildView(int groupPosition, int childPosition,
			boolean isLastChild, View convertView, ViewGroup parent) {
		return null;
	}

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

}

     一个个看，getGroupCount就是返回一级菜单的数目，getChildrenCount就是返回当前一级菜单下的二级菜单的数目，getGroup就是返回groupPosition所关联的data，getChild则是返回两个参数下关联的data，getGroupId直接返回groupPosition，getChildId如果没有要求也是直接返回childPosition，getGroupView和getChildView都是设置view显示的样子，可以在xml中自定义，也可以直接在代码中实例化。剩下的hasStableIds和isChildSelectable直接返回true就行。

    如果要展示的数据比较简单只有一项的话可以直接使用list集合，但是如果数据比较多，比如一个子view中同时显示内容和时间两个属性，就需要在list集合中嵌套一个map集合。在使用集合的时候要考虑将group的数据和child的数据关联起来，这样才能联动显示。先假设一个需求，比如qq的联系人界面，一级界面时好友分组，只有一个textview，二级界面做的简陋一点，一个imageview和一个textview，那么我们先开始写布局文件

res/layout/group.xml 一级菜单的布局

res/layout/child.xml  二级菜单的布局

在自定义的适配器中实例化

public class MyAdapter extends BaseExpandableListAdapter{
	
	private Context mContext;
	private List mGroups;
	private List>> mChilds;
	
	//构造函数中传入上下文对象,group的data,child的data
	public MyAdapter(Context context,List group,List>> child){
		this.mContext = context;
		this.mGroups = group;
		this.mChilds = child;
	}

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

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

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

	@Override
	public Object getChild(int groupPosition, int childPosition) {
		return mChilds.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) {
		LinearLayout mLinearGroup = (LinearLayout) LayoutInflater
				.from(mContext).inflate(R.layout.group, null);
		TextView grouptext = (TextView) mLinearGroup.findViewById(R.id.group_text);
		String text = mGroups.get(groupPosition);
		grouptext.setText(text);
		return mLinearGroup;
	}

	@Override
	public View getChildView(int groupPosition, int childPosition,
			boolean isLastChild, View convertView, ViewGroup parent) {
		LinearLayout mLinearChild = (LinearLayout) LayoutInflater
				.from(mContext).inflate(R.layout.child, null);
		ImageView childimg= (ImageView) mLinearChild.findViewById(R.id.child_img);
		Bitmap bitmap = (Bitmap) mChilds.get(groupPosition).get(childPosition).get("image");
		childimg.setImageBitmap(bitmap);
		TextView childtext = (TextView) mLinearChild.findViewById(R.id.child_txt);
		String text = (String) mChilds.get(groupPosition).get(childPosition).get("text");
		childtext.setText(text);
		return mLinearChild;
	}

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

}

然后在activity中进行调用

public class MainActivity extends Activity {

	private ExpandableListView mListView;
	private MyAdapter mAdapter;
	List group = null;
	List>> child = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		mListView = (ExpandableListView) findViewById(R.id.expand);
		initData();
		mAdapter = new MyAdapter(getApplicationContext(), group, child);
		mListView.setAdapter(mAdapter);
//		mListView.setGroupIndicator(null);  //设置箭头消失
	}

	/**
	 * 传入测试数据，实际获取方法类似
	 */
	private void initData() {
		group = new ArrayList();
		group.add("我的好友");
		group.add("我的家人");
		group.add("我的同学");
		Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
		child = new ArrayList>>();
		for (int i = 0; i < group.size(); i++) {
			List> lists = new ArrayList>();
			for (int j = 0; j < 6; j++) {
				Map map = new HashMap();
				map.put("image",bitmap );
				map.put("text", group.get(i)+j);
				lists.add(map);
			}
			child.add(lists);
		}
	}
}

效果如下：

源码下载链接：http://download.csdn.net/detail/u013926110/8973617