convertView cannot be resolved to a variable

public View getView(int arg0, View arg1, ViewGroup arg2) {
// TODO Auto-generated method stub
ImageView iv1;
if(convertView == null)
{
iv1 = new ImageView(head.this);
iv1.setAdjustViewBounds(true);
iv1.setMaxHeight(150);
iv1.setMaxWidth(158);
iv1.setPadding(5, 5, 5, 5);
}
else
{
iv1 = (ImageView)convertView;
}
iv1.setImageResource(arg0);
return iv1;
}

convertView不能被转换成一个变量

public View getView(int arg0, View arg1, ViewGroup arg2)改为
public View getView(int arg0, View convertView, ViewGroup arg2)

listView 优化？？ 还是啥？

ListView优化 内部类方式
public View getView(int position, View convertView, ViewGroup arg2) {
// TODO Auto-generated method stub
ViewHolder viewHolder = null;
if(convertView==null){
viewHolder = new ViewHolder();
convertView = LayoutInflater.from(c).inflate(R.layout.list_item, null);
viewHolder.image = (ImageView) convertView.findViewById(R.id.item_image);
viewHolder.name = (TextView) convertView.findViewById(R.id.item_name);
viewHolder.path = (TextView) convertView.findViewById(R.id.item_path);
convertView.setTag(viewHolder);
}else{
viewHolder = (ViewHolder) convertView.getTag();
}

        viewHolder.image.setImageDrawable(DrawAbleUtil.getBitmap(list.get(position).getPath()));
        viewHolder.name.setText(list.get(position).getName());
        viewHolder.path.setText(list.get(position).getPath());

    return convertView;
}

class ViewHolder{
    ImageView image;
    TextView name,path;
}