if?(chart.add(item,?Integer.valueOf(snumber)))//這里報空怎么回事，下面是add方法
{
????return?true;
}
else
{
????return?false;
}

//添加商品進購物車的方法
public?boolean?add(Items?item,int?snumber)
{
????if?(goods.containsKey(item))
????{
????????goods.put(item,?goods.get(item)+snumber);
????}
????else
????{
????????goods.put(item,?snumber);
????}
????calTo();//重新計算購物車的總金額
????return?true;
}