ExpandableListView（下拉列表）实现

package liu;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.BaseExpandableListAdapter;import android.widget.ExpandableListView;import android.widget.ExpandableListView.OnChildClickListener;import android.widget.ImageView;import android.widget.TextView;import android.widget.Toast;import com.example.demo_0330.R;public class ExpandableListView_Activity extends Activity {private ExpandableListView listview;private String[] groups = { "家人", "朋友", "亲戚" };private String[][] groupser = { { "关羽", "刘备", "张飞" },{ "孙悟空", "沙和尚", "猪八戒" }, { "旭哥", "琳哥", "徐哥" } };protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.expandablelistview_activity);listview = (ExpandableListView) findViewById(R.id.yi);listview.setAdapter(new adapter());//点击事件listview.setOnChildClickListener(new OnChildClickListener() {public boolean onChildClick(ExpandableListView parent, View v,int groupPosition, int childPosition, long id) {Toast.makeText(ExpandableListView_Activity.this, groupser[groupPosition][childPosition], 0).show();return false;}});}// 适配器class adapter extends BaseExpandableListAdapter {// 总的组数public int getGroupCount() {return groups.length;}// 子类的总数public int getChildrenCount(int groupPosition) {return groupser[groupPosition].length;}// 获取二级分类对象public Object getGroup(int groupPosition) {return groups[groupPosition];}// 获取二级分类里的对象public Object getChild(int groupPosition, int childPosition) {return groupser[groupPosition][groupPosition];}// 返回相应的idpublic long getGroupId(int groupPosition) {return groupPosition;}// 返回相应的idpublic long getChildId(int groupPosition, int childPosition) {return childPosition;}// 返回状态 可以用不重写public boolean hasStableIds() {// TODO Auto-generated method stubreturn false;}// 分组布局public View getGroupView(int groupPosition, boolean isExpanded,View convertView, ViewGroup parent) {if (convertView == null) {convertView = getLayoutInflater().inflate(R.layout.group_layout, null);}ImageView iv = (ImageView) convertView.findViewById(R.id.tupian);TextView tv = (TextView) convertView.findViewById(R.id.title);tv.setText(groups[groupPosition]);return convertView;}// 分组内部布局，每一组的布局public View getChildView(int groupPosition, int childPosition,boolean isLastChild, View convertView, ViewGroup parent) {if (convertView == null) {convertView = getLayoutInflater().inflate(R.layout.group_erji_layout, null);}ImageView iv = (ImageView) convertView.findViewById(R.id.tupian);TextView tv = (TextView) convertView.findViewById(R.id.title);tv.setText(groupser[groupPosition][childPosition]);return convertView;}// 二级是否可以被选中public boolean isChildSelectable(int groupPosition, int childPosition) {return true;}}}