Android（java）学习笔记197：使用ExpandableListView组件（ListView的扩展）

<LinearLayout 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:orientation="vertical"
    tools:context="com.himi.expandablelistview.MainActivity" >
    <TextView 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="QQ通讯录"
        android:textSize="30sp"
        android:textColor="#55ff0000"
        android:gravity="center_horizontal"
        />

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

</LinearLayout>

    private String[] groups = {"家人","同学","同事"};
    private String[][] childs = { {"老爸","老妈"}, {"刘德华","黎明","郭富城","张学友"}, {"马云","比尔盖茨",
        "巴菲特"} };
    private int[][] childs_imgs = { { R.drawable.img1, R.drawable.img2 },
            { R.drawable.img3, R.drawable.img4 , R.drawable.img5, R.drawable.img6},
            { R.drawable.img7, R.drawable.img8 , R.drawable.img9}
    };

package com.himi.expandablelistview.adpater;


import android.view.ViewGroup.LayoutParams;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.himi.expandablelistview.R;

/**
 * 自定义适配器MyExpandablelistviewAdapter
 * @author Administrator
 *
 */
public class MyExpandablelistviewAdapter extends BaseExpandableListAdapter {
    private Context context  ;
    private String[] groups = {"家人","同学","同事"};
    private String[][] childs = { {"老爸","老妈"}, {"刘德华","黎明","郭富城","张学友"}, {"马云","比尔盖茨",
        "巴菲特"} };
    private int[][] childs_imgs = { { R.drawable.img1, R.drawable.img2 },
            { R.drawable.img3, R.drawable.img4 , R.drawable.img5, R.drawable.img6},
            { R.drawable.img7, R.drawable.img8 , R.drawable.img9}
    };
    
    //引入一个字段context，方便Activity实例化MyExpandablelistviewAdapter
    public MyExpandablelistviewAdapter(Context context) {
         this.context = context;
    }

    //获取一级菜单的分组数目，比如这里就是3组："我的好友","同学","同事"
    public int getGroupCount() {
        return groups.length;
    }
    
    //获取每个一节菜单中二级菜单的分组数目,比如"家人"中有2个条目("老爸","老妈")
    public int getChildrenCount(int groupPosition) {
        return childs[groupPosition].length;
    }
   //获取每个一级菜单子项对象
    public String getGroup(int groupPosition) {
        return groups[groupPosition];
    }
    //获取每个二级菜单子项对象
    public String getChild(int groupPosition, int childPosition) {
        return childs[groupPosition][childPosition];
    }
    
    //获取每个一级菜单子项对象Id
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }
    //获取每个二级菜单子项对象Id
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }
 
    
    /**
     * hasStableIds有关于MyExpandablelistviewAdapter适配器刷新顺序
     * getGroupId和getChildId两个方法获取对象Id，获取到的Id,ExpandableListView会根据这个Id确定位置显示内容
     * 然而Id是否有效稳定是由hasStableIds决定的，也就是说：这个方法就是判断item的id是否稳定，
     * 如果有自己的id也就是true，那就是稳定，否则不稳定，则根据item位置来确定id
     * 
     */
    public boolean hasStableIds() {
        return true;
    }

    //渲染一级菜单
    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {
        if(convertView == null) {
        /**
         * LayoutInflater是一个抽象类，它的inflate方法可以把一个xml文件转化为View对象
         * 对于一个没有被载入或者想要动态载入的界面，都需要使用LayoutInflater.inflate()来载入
         * 刚刚说明了：LayoutInflater是一个抽象类,要获取LayoutInflater的实例;
         * 获得 LayoutInflater 实例的三种方式:
         *  1.LayoutInflater inflater = getLayoutInflater();  //调用Activity的getLayoutInflater()
         *  
         *  2.LayoutInflater localinflater =(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
         *  
         *  3. LayoutInflater inflater = LayoutInflater.from(context); 
         *  上面三种方法的本质是一样的
         */
             LayoutInflater minflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
             convertView = minflater.inflate(R.layout.group_item,null);     
        }
        TextView tv = (TextView) convertView.findViewById(R.id.textview_group);
        tv.setText(groups[groupPosition]);
        tv.setTextSize(25);
        tv.setPadding(15, 5, 0, 0);
        return convertView;
    }
    //渲染二级菜单
    public View getChildView(int groupPosition, int childPosition,
            boolean isLastChild, View convertView, ViewGroup parent) {
        if(convertView == null) {
             LayoutInflater minflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
             convertView = minflater.inflate(R.layout.child_item,null);     
        }
        ImageView iv = (ImageView) convertView.findViewById(R.id.imageview_child);
        TextView tv = (TextView) convertView.findViewById(R.id.textview_child);
        
        iv.setImageResource(childs_imgs[groupPosition][childPosition]);
        //导入的包为：import android.view.ViewGroup.LayoutParams;
        LayoutParams params = iv.getLayoutParams();
        params.width = 200;
        params.height = 200;
        iv.setLayoutParams(params);
        
        tv.setText(childs[groupPosition][childPosition]);
        //记得return convertView
        return convertView;
    }

    //true:让子项可选 ;     false:让子项不可选
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }

}

package com.himi.expandablelistview;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.Toast;

import com.himi.expandablelistview.adpater.MyExpandablelistviewAdapter;

public class MainActivity extends Activity {
    private ExpandableListView expan_listview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        expan_listview = (ExpandableListView) findViewById(R.id.expandablelv);
        expan_listview.setAdapter(new MyExpandablelistviewAdapter(this));
        expan_listview.setOnChildClickListener(new OnChildClickListener() {
            
            public boolean onChildClick(ExpandableListView parent, View v,
                    int groupPosition, int childPosition, long id) {

                 Toast.makeText(MainActivity.this, "你点击的是第"+(groupPosition+1)+"的菜单下的第"+(childPosition+1)+"选项", 0).show();
                return false;
            }
        });
    }
    

    
}