Java 而那些不是员工的人——我如何才能确保它在执行时不会出错？

“雇员”应该能够看到数据库中的所有订单。而非员工必须能够根据其用户ID查看自己的订单

问题是我的行政部门犯了错误

错误说明：

变量p可能尚未初始化

例如，如果我给出我的

PreparedStatement p=null

，它告诉我第一个SQL是“NullPointerException”

---

作为一个起点，我只使用

OrderID

，

length

，

width

，

height

，

date

和

shippingDate

和

shipped

您也需要在

if

块中

准备陈述p

（就像在

else

中一样）。像

ArrayList<Order> orders = new ArrayList<>(); // tom collection.

    try {
        Connection cc = Connector.connection();
        String SQL;
        PreparedStatement p;
        if("employee".equals(user.getRole()))
        {
            SQL = "SELECT * FROM orders ORDER BY orderId DESC";
        }
        else
        {
            SQL = "SELECT * FROM orders WHERE userId = ? ORDER BY orderId DESC";
            p = cc.prepareStatement(SQL);
            p.setInt(1, user.getId());
        }



        try(ResultSet rs = p.executeQuery();)
        {
            while(rs.next())
            {

                orders.add(new Order(
                            rs.getInt("orderId"), 
                            user, 
                            rs.getInt("length"), 
                            rs.getInt("width"), 
                            rs.getInt("height"), 
                            rs.getDate("date"), 
                            rs.getDate("shippingDate"), 
                            rs.getBoolean("shipped")));
            }
        }

        return orders;
    }
    catch(ClassNotFoundException | SQLException ex){
        throw new Other(ex.getMessage());
    }

public Order(int orderid, User user, int length, int width, int height, Date dt, Date shippingDate, boolean shipped) {
    this.OrderId = orderid;
    this.user = user;
    this.length = length;
    this.width = width;
    this.height = height;
    this.dt = dt;
    this.shippingDate = shippingDate;
    this.shipped = shipped;
}

PreparedStatement p;
if("employee".equals(user.getRole())) {
    SQL = "SELECT * FROM orders ORDER BY orderId DESC";
    // Add this...
    p = cc.prepareStatement(SQL);
} else {
    SQL = "SELECT * FROM orders WHERE userId = ? ORDER BY orderId DESC";
    // Just like here
    p = cc.prepareStatement(SQL);
    p.setInt(1, user.getId());
}