Question

我有3个班级：

运动服（超级）
泽西岛（子类）
驱动程序

我的驱动程序中有一个ArrayList来保存我创建的所有球衣。当用户输入所有值（库存，价格，产品，团队，工具包，尺寸，性别）时，然后它显示它们显示为null：

Product: null
In stock: 0
Price: 0
Team: 
Kit: 
Size: 
Gender:

超类（运动装）有变量stock, price and product（所以我可以包括其他产品，而不仅仅是球衣）

子类（Jersey）包含变量team, kit, size, gender。它还包含显示上述内容的方法jerseyDisplay()。

在输入值后的驱动程序中，我输入：

Jersey jersey = new Sportswear(stock, price, product, team, kit, size, gender);

sportswear.add(jersey);


jersey.jerseyDisplay();

这完全错了吗？为什么输入的值不显示？

子类jerseyDisplay()中的Jersey方法是：

public void jerseyDisplay()
    {
        super.sportswearDisplay();

        System.out.println("Team: "+team);

        System.out.println("Kit: "+kit);

        System.out.println("Size: "+size);

        System.out.println("Gender: "+gender);
    }

@DessertIvy这是Sportswear的超级课程：

public class Sportswear
{
    //instance variables
    private int stock;
    private float price;
    private String product;

    //blank constructor
    public Sportswear()
    {
        this.stock = 0;
        this.price = 0;
        this.product = "";
    }

    //detailed constructor
    public Sportswear(int s, float p, String pd)
    {
        this.stock = stock;
        this.price = price;
        this.product = product;
    }

    //setters
    public void setStock(int stock)
    {
        this.stock = stock;
    }

    public void setPrice(float price)
    {
        this.price = price;
    }

    public void setProduct(String product)
    {
        this.product = product;
    }

    //getters
    public int getStock()
    {
        return stock;
    }

    public float getPrice()
    {
        return price;
    }

    public String getProduct()
    {
        return product;
    }

    //increase stock
    public int increaseStock()
    {
        stock = stock++;
        return stock;
    }

    //decrease stock
    public int decreaseStock()
    {
        stock = stock - 1;
        return stock;
    }

    public void sportswearDisplay()
    {
        System.out.println("Product: "+product);
        System.out.println("In stock: "+stock);
        System.out.println("Price: "+stock);
    }

}

Jersey子类中的构造函数：

public Jersey(int stock, float price, String product, String team, String kit, String size, String gender)
    {
        super(stock, price, product);
        this.team = "";
        this.kit = "";
        this.size = "";
        this.gender = "";
    }

Answer 1

问题在你的2个构造者中：

    //detailed constructor
public Sportswear(int s, float p, String pd)
{
    this.stock = stock;
    this.price = price;
    this.product = product;
}

和

public Jersey(int stock, float price, String product, String team, String kit, String size, String gender)
{
    super(stock, price, product);
    this.team = "";
    this.kit = "";
    this.size = "";
    this.gender = "";
}

您应该使用作为参数传递的值初始化变量...或使用您的setXXX方法。在构造函数中，它应如下所示：

        //detailed constructor
public Sportswear(int s, float p, String pd)
{
    this.stock = s;
    this.price = p;
    this.product = pd;
}

另外，如前所述，这一行 Jersey jersey = new Sportswear(stock, price, product, team, kit, size, gender);甚至不应该编译......你可能意味着Jersey jersey = new Jersey(stock, price, product, team, kit, size, gender);

我的对象值不会保存。显示null

1 个答案: