Question

我正在尝试从主要信息中检索所有客户的信息。我有一个CustomerManager类和一个类main（它是：main（String [] args））这是CustomerManager类的代码，它使用hashmap作为集合
公共类CustomerManager {

private static final Map<String, Customer> customersManager = new HashMap<> ();

  public static void addCustomer(Customer c){
       // Customers
    customersManager.put(c.getID(), c);
    customersManager.put ("ID1", new Customer ("ID1","Jonathan", "Mifsud", "Test Address", 21345678, "L001"));
    customersManager.put ("ID2", new Customer ("ID2","David", "Aguis", "2nd Address", 21456778, "L002"));
    customersManager.put ("ID3", new Customer ("ID3","Frank", "Mamo", "example Address", 21987653, "L003"));
  }

  public static void findCustomer(Customer c){
     customersManager.put(c.getID(), c);
  }

  public static void deleteCustomer(Customer c){
      customersManager.remove(c.getID());
  }

}
现在如何从CustomerManagement类检索客户信息到main。我试过这个：

System.out.println（“插入客户ID：”）;
customersManager.findCustomer（C）;

但它给了我一个错误：
变量c可能没有被初始化

Answer 1

在toString()类中添加以下Customer方法以打印其内容：

@Override
public String toString() {
    return "Customer [fname=" + fname 
        +", lname=" + lname 
        +", address=" + address 
        +", phone=" + phone
        +", loyaltyCard=" + loyaltyCard + "]";
}

使用HashMap检索

1 个答案: