ExpandableListView视图树简单应用

package com.example.tree;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsoluteLayout;
import android.widget.AbsoluteLayout.LayoutParams;
import android.widget.AbsListView;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;

public class TreeAdapter extends BaseExpandableListAdapter {
    private String[] groups;
    private String[][] chlids;
    private Context context;

    public TreeAdapter(String[] groups, String[][] chlids, Context context) {
        this.groups = groups;
        this.chlids = chlids;
        this.context = context;
    }
    //父项长度
    @Override
    public int getGroupCount() {
        // TODO Auto-generated method stub
        return groups.length;
    }
    //子项长度
    @Override
    public int getChildrenCount(int groupPosition) {
        // TODO Auto-generated method stub
        return chlids[groupPosition].length;
    }
    //返回父项对象
    @Override
    public Object getGroup(int groupPosition) {
        // TODO Auto-generated method stub
        return groups[groupPosition];
    }
    //返回子项对象
    @Override
    public Object getChild(int groupPosition, int childPosition) {
        // TODO Auto-generated method stub
        return chlids[groupPosition][childPosition];
    }
    //返回父项id
    @Override
    public long getGroupId(int groupPosition) {
        // TODO Auto-generated method stub
        return groupPosition;
    }
    //返回子项id
    @Override
    public long getChildId(int groupPosition, int childPosition) {
        // TODO Auto-generated method stub
        return childPosition;
    }
    
    @Override
    public boolean hasStableIds() {
        // TODO Auto-generated method stub
        return true;
    }
    //创建textview方法
    private TextView buildTextView() {
        AbsListView.LayoutParams p = new AbsListView.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT);
        TextView tv = new TextView(context);
        tv.setLayoutParams(p);
        tv.setTextSize(20);
        tv.setPadding(60, 5, 10, 5);
        return tv;
    }
    //返回父项视图
    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {
        TextView tv = buildTextView();
        tv.setText(groups[groupPosition].toString());
        return tv;
    }
    //返回子项视图
    @Override
    public View getChildView(int groupPosition, int childPosition,
            boolean isLastChild, View convertView, ViewGroup parent) {
        TextView tv = buildTextView();
        tv.setText(chlids[groupPosition][childPosition].toString());
        return tv;
    }
    //设置子项是否可以点击
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        // TODO Auto-generated method stub
        return true;
    }

}

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <ExpandableListView
        android:id="@+id/ex"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
       />

</RelativeLayout>

package com.example.tree;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnGroupClickListener;
import android.widget.ExpandableListView.OnGroupCollapseListener;
import android.widget.ExpandableListView.OnGroupExpandListener;
import android.widget.Toast;
import android.widget.ExpandableListView.OnChildClickListener;

public class MainActivity extends Activity {
    private ExpandableListView ex;
    private TreeAdapter adapter;
    private String[] groups = { "吉林", "辽宁", "黑龙江", "湖南" };
    private String[][] childs = { { "长春", "四平", "通话" }, { "大连", "沈阳" },
            { "绥芬河", "哈尔冰" }, { "长沙" } };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ex = (ExpandableListView) findViewById(R.id.ex);
        adapter = new TreeAdapter(groups, childs, this);
        //注册上下文菜单 
        //super.registerForContextMenu(ex);
        ex.setAdapter(adapter);
        // 子项的点击事件
        ex.setOnChildClickListener(new OnChildClickListener() {

            @Override
            public boolean onChildClick(ExpandableListView parent, View v,
                    int groupPosition, int childPosition, long id) {
                Toast.makeText(MainActivity.this,
                        childs[groupPosition][childPosition], 1000).show();
                return false;
            }
        });
        //父项点击事件
        ex.setOnGroupClickListener(new OnGroupClickListener() {
            
            @Override
            public boolean onGroupClick(ExpandableListView parent, View v,
                    int groupPosition, long id) {
                // TODO Auto-generated method stub
                Toast.makeText(MainActivity.this,
                        groups[groupPosition], 1000).show();
                return false;
            }
        });
        //父项关闭事件
        ex.setOnGroupCollapseListener(new OnGroupCollapseListener() {
            
            @Override
            public void onGroupCollapse(int groupPosition) {
                // TODO Auto-generated method stub
                Toast.makeText(MainActivity.this,
                        "关闭", 1000).show();
            }
        });
        //父项打开事件
        ex.setOnGroupExpandListener(new OnGroupExpandListener() {
            
            @Override
            public void onGroupExpand(int groupPosition) {
                // TODO Auto-generated method stub
                Toast.makeText(MainActivity.this,
                        "打开", 1000).show();
            }
        });
    }

}