Java 添加 ArrayList 的方法未定义类型 <OBJECT>

Question

我正在为我的家庭作业构建一个 java 程序，我必须在其中向特定商店添加产品。尝试从 Store class.

添加到 ArrayList 时遇到问题

我有 class 个产品如下：

class Product {

    private String pName;
    private int pPrice;
    private int pQty;

    public Product (String pName, int pPrice, int pQty) {
        this.pName = pName;
        this.pPrice = pPrice;
        this.pQty = pQty;
    }
}

和class存储如下：

class Store {

    private String storeName;
    ArrayList<Product> pList =new ArrayList<>();

    public Store() {
        String name = storeName;
        pList = new ArrayList<Product>();
    }
    public Store(String newStoreName,ArrayList<Product> newPList) {
        this.storeName = newStoreName;
        this.pList = newPList;
    }

    void setName(String storeName) {
        this.storeName = storeName;
    }
    void setProduct(Product pList) {
        pList.add(this.pList);//This return method add undefined for type Product, how to solve this error?
    }
    String getName() {
        return storeName;
    }
    ArrayList<Product> getProductList() {
        return pList;
    }
}

Answer 1

void setProduct(Product pList) {
    pList.add(this.pList);//This return method add undefined for type Product, how to solve this error?
}

应该是

void addProduct(Product product) {
    pList.add(product);
}

Answer 2

1 - 你应该像下面这样改变你的构造函数：_-

public Store(String newStoreName,ArrayList<Product> newPList) {
    this.storeName = newStoreName;
    pList.addAll(newPList);// This is standard and recommended way to add all element in list. 
}

2 - 更改您的 setProduct 方法。这个运算符不是这样工作的。

void setProduct(Product pList) {
    pList.add(pList); 
}

Java 添加 ArrayList 的方法未定义类型 <OBJECT>

Java Method add ArrayList is undefined for the type <OBJECT>

java

oop

arraylist

object

undefined