java - 具有泛型类型参数的方法可以传递泛型类型参数

Question

我的 Customer 类中有带有 getter 和 setter 的实例

private Collection<CustomersDetails> customerDetails = new ArrayList<CustomersDetails>();

    public Collection<CustomersDetails> getCustomerDetails() {
        return customerDetails;
    }
    public void setCustomerDetails(Collection<CustomersDetails> customerDetails) {
        this.customerDetails = customerDetails;
    }

但是当我试图通过时

CustomersDetails customersDetails = new CustomersDetails();

customersDetails.set....
customersDetails.set....


Customer customer = new Customer();
customer.setCustomerDetails(customersDetails);

它给了我错误

The method setCustomerDetails(Collection<CustomersDetails>) in the type Customer is not applicable for the arguments (CustomersDetails) 

为什么会这样，当我的 Collection 是 CustomersDetails 类型时？

Answer 1

您的Customer类有一个方法

public void setCustomerDetails(Collection<CustomersDetails> customerDetails) {
    this.customerDetails = customerDetails;
}

您正尝试使用 CustomersDetails 类型的参数来调用它。一个CustomersDetails不是Collection<CustomersDetails> 。将元素包装在 List 中或其他Collection .

类似于

customer.setCustomerDetails(Arrays.asList(customersDetails));