Android学习笔记之viewholder

在adapter中通过使用静态内部类（viewholder）缓存组件的引用来防止ListView刷新时重新LayoutInflater跟findViewById从而达到优化的目的。示例如下：

 

 

@Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if(convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.menu_item_layout, null);
            viewHolder = new ViewHolder();
            viewHolder.btn_menu = (Button) convertView.findViewById(R.id.btn_menu);
            viewHolder.tv_title = (TextView)convertView.findViewById(R.id.tv_title);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder)convertView.getTag();
        }
        final int[] d= data.get(position);
        viewHolder.btn_menu.setBackgroundResource(d[0]);
        viewHolder.btn_menu.setFocusable(false);
        viewHolder.btn_menu.setFocusableInTouchMode(false);
        viewHolder.tv_title.setText(d[1]);
        viewHolder.tv_title.setTextSize(12);
        viewHolder.tv_title.setTextColor(Color.WHITE);
        final View t_View = convertView;
        viewHolder.btn_menu.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                if(mItemListener != null) {
                    mItemListener.onClickListener(position, t_View);
                }
            }
        });
        
        return convertView;
    }
    
    public static class ViewHolder {
        public Button btn_menu;
        public TextView tv_title;
    }