Java 用于打印客户对象的数组列表

如何使用Customer类型的数组列表（它有两个子类，nonmember和member）通过比较打印出所有Customer对象？换句话说，我想检查某个索引处的数组列表，检查它是非成员对象还是成员对象，并相应地打印输出。这是我的密码：

ArrayList<Customer> customerList = new ArrayList<Customer>();

for(int i = 0; i < customerList.size(); i++)
{
    if(customerList.get(i) == // nonmember)                     
    {
        // want to use toString in NonMemberCustomer class
    }
    else // member
    {       
        // use toString in MemberCustomer class to print output.
    }
}

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使用

Customer

作为参数化类型声明arraylist：

// So that the polymorphism would work
List<Customer> customerList = new ArrayList<>();

课程：（例如）

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非常感谢您的洞察力。我会试试这个。

public String toString()
{
    return "NonMember Customer:" + super.toString() +
           "Visit Fee:\t\t" + visitFee + "\n\n";
}

// So that the polymorphism would work
List<Customer> customerList = new ArrayList<>();

for(int i =0; i < customerList.size();i++) {
    // Implicit call to the toString() method
    System.out.println(customerList.get(i)); 
}

class Customer {
    // properties & methods

    @Override
    public String toString() {
        System.out.println("The customer's toString !");
    }
}

class Member extends Customer {
    // properties & methods

    @Override
    public String toString() {
        System.out.println("The member's toString !");
    }
}

class NonMember extends Customer {
    // properties & methods

    @Override
    public String toString() {
        System.out.println("The nonmember's toString !");
    }
}