要通过方法传递的参数

Question

我正在创建一个构造函数，我被告知要做的是：

• “ quantity参数将传递给testQuantity方法。”

• “在此之后，应通过传递productName参数来调用getPrice方法”

到目前为止，这是我为该构造函数准备的内容，设置了变量，我只需要一些帮助。

    public Order (String productName, int quantity) {
        orderNum = orderNum + 1;
        productName = this.productName;
        quantity = testQuantity; 
        if (isValidOrder = true)

Answer 1

在这种情况下，构造函数应如下所示：

public Order (String productName, int quantity) {
    testQuantity(quantity); //Probably this should return a boolean or throw a exception
    double price = getPrice(productName); //Probably it should return a quantity.
    //other operations needed.
    }

Answer 2

public Order (String productName, int quantity) {
        orderNum = orderNum + 1;
        productName = this.productName;
        quantity = testQuantity; 
        if (isValidOrder = true)
        .....
        testQuantity(quantity);
        getPrice(productName);

在testQuantity和getPrice方法中，接收从构造函数传递的参数。

尽管quantity = testQuantity;但不确定这行代码是quantity = testQuantity;

Answer 3

productName = this.productName;

只是考虑不要这样做。 实例变量在声明时被分配了一个值，并且在实例化时已经被定义-您只能使用它的值，而productName参数是无用的。 还是在声明的地方没有给出值-然后是构造函数将值分配给该变量，在此之前您不能使用它。

Answer 4

public Order (String productName, int quantity){
    // same as you did "orderNum = orderNum + 1" and "orderNum += 1".
    // I added "this" in the beginning because "orderNum" is not a variable
    // you declared in the constructor so it will be from the class.
    // BTW make sure you initialized the variable.
    this.orderNum++;

    // I think you are doing this part by mistake without understanding. So I commented this part.
    // what this code means is: set the value of variable "productName" (that you declared in the
    // method, the first parameter) of the value of variable "this.productName" (that you declared
    // in the root of the class, like orderNum)
    // productName = this.productName;

    // The quantity parameter is to be passed to the testQuantity method.
    // general way to call a method is <method name>(); "()" means execute
    // any information you want to pass as parameter goes inside the parenthesis
    testQuantity(quantity);

    // Following this a call to the getPrice method should be made passing the productName parameter
    // same rules here.
    getPrice(productName);

    // However, you are not storing the values after you calling the methods.
    // if you have any further questions feel free to comment and I will reply asap.
    // Good Luck!
}

Answer 5

通过以下代码，

1. 将数量传递给testQuantity方法：testQuantity（quantity）;

2. 获得价格：getPrice（productName）;

祝好运 ！！！