ExpandableListView是android中可以实现下拉list的一个控件，是一个垂直滚动的心事两个级别列表项手风琴试图，列表项是来自ExpandableListViewaAdapter，组可以单独展开。
重要方法：
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
expandableListView.setDivider();这个是设定每个Group之间的分割线。
expandableListView.setGroupIndicator();这个是设定每个Group之前的那个图标。
expandableListView.collapseGroup(int group); 将第group组收起
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。
1.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。
如下案例：
实现这样的效果需要自定义一个Adapter，自定义的Adapter继承BaseExpandableListAdapter，重写getGroupView和
getChildView方法时实例化自己的布局文件就可以了。下面是实现代码：
主布局文件 main.xml
<?xmlversion="1.0"encoding="utf-8"?> <LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" android:background="#ffffff" > <ExpandableListView android:id="@+id/elist" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#ffffff" /> </LinearLayout>
子视图布局文件 child_layout.xml
<?xmlversion="1.0"encoding="utf-8"?> <LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:paddingLeft="30dp" > <ImageView android:id="@+id/civ" android:layout_height="wrap_content" android:layout_width="wrap_content" android:src="@drawable/ren" android:padding="5dp" /> <TextView android:id="@+id/ctv" android:layout_height="wrap_content" android:layout_width="wrap_content" android:padding="5dp" android:textColor="#000000" /> </LinearLayout>
分组视图布局文件 group_layout.xml
<?xmlversion="1.0"encoding="utf-8"?> <RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/grlayout" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <TextView android:id="@+id/gtv" android:layout_width="wrap_content" android:layout_height="fill_parent" android:paddingLeft="20dp" android:textColor="#000000" /> <ImageView android:id="@+id/giv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_centerVertical="true" android:paddingRight="10dp" android:src="@drawable/jia" /> </RelativeLayout>
自定义适配器 MyElistAdapter.java
publicclass MyElistAdapter extends BaseExpandableListAdapter { // 分组数据 private String[] group = { "A组", "B组", "C组", "D组" }; private String[][] child = { { "A01", "A02", "A03" }, { "B01", "B02", "B03" }, { "C01", "C02", "C03" }, { "D04", "D05", "D06" } }; private Context mContext; public MyElistAdapter(Context mContext) { super(); this.mContext = mContext; } @Override public int getGroupCount() { return group.length; } @Override public int getChildrenCount(int groupPosition) { return child[groupPosition].length; } @Override public Object getGroup(int groupPosition) { return group[groupPosition]; } @Override public Object getChild(int groupPosition, int childPosition) { return child[groupPosition][childPosition]; } @Override public long getGroupId(int groupPosition) { return groupPosition; } @Override public long getChildId(int groupPosition, int childPosition) { returnchildPosition; } @Override public boolean hasStableIds() { return true; } @Override public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) { // 实例化布局文件 RelativeLayout glayout = (RelativeLayout) LayoutInflater.from(mContext) .inflate(R.layout.group_layout, null); ImageView iv = (ImageView) glayout.findViewById(R.id.giv); // 判断分组是否展开，分别传入不同的图片资源 if (isExpanded) { iv.setImageResource(R.drawable.jian); } else { iv.setImageResource(R.drawable.jia); } TextView tv = (TextView) glayout.findViewById(R.id.gtv); tv.setText(this.getGroup(groupPosition).toString()); return glayout; } @Override public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) { // 实例化布局文件 LinearLayout clayout = (LinearLayout) LayoutInflater.from(mContext) .inflate(R.layout.child_layout, null); TextView tv = (TextView) clayout.findViewById(R.id.ctv); tv.setText(getChild(groupPosition, childPosition).toString()); return clayout; } @Override public boolean isChildSelectable(int groupPosition, int childPosition) { return true; } }
MainActivity.java
publicclass ExpandableTestActivity extends Activity { private ExpandableListView elistview; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); elistview = (ExpandableListView) findViewById(R.id.elist); //这里要把系统自带的图标去掉 elistview.setGroupIndicator(null); elistview.setAdapter(new ElistAdapter(this)); // elistview.setChildDivider(null); // elistview.setDivider(null); } }