Android ListView使用BaseAdapter与ListView的优化 (转至 http://www.open-open.com/lib/view/open1339485728006.html)

publicclass MyListViewBase extends Activity {
    
    private ListView lv;
    //定义一个动态数组     
    ArrayList<HashMap<String, Object>>listItem;/** Called when the activity is first created. */ 
    
    @Override
    publicvoid onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        lv = (ListView) findViewById(R.id.lv);
        MyAdapter mAdapter = new MyAdapter(this);//得到一个MyAdapter对象 
        lv.setAdapter(mAdapter);//为ListView绑定Adapter 
        /**为ListView添加点击事件*/ 
        lv.setOnItemClickListener(new OnItemClickListener() {
            @Override
            publicvoid onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {
                Log.v("MyListViewBase", "你点击了ListView条目" + arg2);//在LogCat中输出信息                 
            }
        });
    }
    /**添加一个得到数据的方法，方便使用*/ 
    private ArrayList<HashMap<String, Object>> getDate(){
        ArrayList<HashMap<String, Object>> listItem = new ArrayList<HashMap<String,Object>>();
        /**为动态数组添加数据*/     
        for(int i=0;i<30;i++)  
         {  
             HashMap<String, Object> map = new HashMap<String, Object>();  
             map.put("ItemTitle", "第"+i+"行");  
             map.put("ItemText", "这是第"+i+"行");  
             listItem.add(map);  
         } 
        return listItem;
    }
    /** 新建一个类继承BaseAdapter，实现视图与数据的绑定
     */ 
    privateclass MyAdapter extends BaseAdapter {
        private LayoutInflater mInflater;//得到一个LayoutInfalter对象用来导入布局  
        
        /**构造函数*/ 
        public MyAdapter(Context context) {
            this.mInflater = LayoutInflater.from(context);
        }

        @Override
        publicint getCount() {
            return getDate().size();//返回数组的长度         
        }

        @Override
        public Object getItem(int position) {
            returnnull;
        }

        @Override
        publiclong getItemId(int position) {
            return 0;
        }
        
        /**书中详细解释该方法*/         
        @Override
        public View getView(finalint position, View convertView, ViewGroup parent) {
             ViewHolder holder;
            //观察convertView随ListView滚动情况             
             Log.v("MyListViewBase", "getView " + position + " " + convertView);
            if (convertView == null) {
                     convertView = mInflater.inflate(R.layout.item,null);
                     holder = new ViewHolder();
                    /**得到各个控件的对象*/                     
                    holder.title = (TextView) convertView.findViewById(R.id.ItemTitle);
                    holder.text = (TextView) convertView.findViewById(R.id.ItemText);
                    holder.bt = (Button) convertView.findViewById(R.id.ItemButton);
                    convertView.setTag(holder);//绑定ViewHolder对象                    
            }
            else{
                    holder = (ViewHolder)convertView.getTag();//取出ViewHolder对象                   
            }
            /**设置TextView显示的内容，即我们存放在动态数组中的数据*/             
            holder.title.setText(getDate().get(position).get("ItemTitle").toString());
            holder.text.setText(getDate().get(position).get("ItemText").toString());
            
            /**为Button添加点击事件*/              
            holder.bt.setOnClickListener(new OnClickListener() {
                @Override
                publicvoid onClick(View v) {
                    Log.v("MyListViewBase", "你点击了按钮" + position);//打印Button的点击信息                     
                }
            });
            
            return convertView;
        }
    
    }
    
    /**存放控件*/ 
    publicfinalclass ViewHolder{
        public TextView title;
        public TextView text;
        public Button   bt;
    }
}