练习2 练习目标－使用引用类型的成员变量：在本练习中，将扩展银行项目，添加一个（客户类）Customer类。Customer类将包含一个Account对象。

package banking;

public class Customer {

    private String firstName;
    private String lastName;
    private Account account;
    
    public Customer(String firstName,String lastName)
    {
        this.firstName=firstName;
        this.lastName=lastName;
    }
    public String getFirstName()
    {
        return firstName;
    }
    public String getLastName()
    {
        return lastName;
    }
    public Account getAccount() {
        return account;
    }
    public void setAccount(Account account) {
        this.account = account;
    }
    
}