如何定义一种将新项目输入Java中现有标志性的方法

Question

当我想将项目添加到预定义的Hashtable时，通常很简单。但是，每当我想定义诸如addNewCustomer()之类的方法并尝试在该方法内使用customerHashtable.put(...);函数时，它就不起作用。请帮助我定义一种可与现有标签合作的方法，让我在其中添加新对象（客户）。

这是以下代码：

    public static void main(String[] args) {
           Hashtable<Integer, Customer> customerHashtable = new Hashtable<Integer, Customer>();
           customerHashtable.put (1, new Customer("david", "[phone]", new Address("AR", "77555")));
           Customer customer = new Customer("mark", "13035003433", new Address("AR", "77200"));
           public void addNewCustomers(int key, Customer customer) { 
           customerHashtable.put(key, customer);
           System.out.println(customerHashtable.get(key).toString());
           }
    }
}

Answer 1

您必须将addNewCutomers()方法放在main方法之外，并为HashTable创建一个类字段。假设您对静态上下文还可以，则可以看起来像这样：

public class HashtableDemo {
    static Hashtable<Integer, Customer> customerHashtable;
    public static void main(String[] args) {
        customerHashtable = new Hashtable<Integer, Customer>();
        customerHashtable.put (1, new Customer("david", "[phone]", new Address("AR", "77555")));
        Customer customer = new Customer("mark", "13035003433", new Address("AR", "77200"));
        addNewCustomers(2, customer);
    }
    public static void addNewCustomers(int key, Customer customer) { 
        customerHashtable.put(key, customer);
        System.out.println(customerHashtable.get(key).toString());
    }
}