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;

    }