阅读以下说明和 Java程序，填补代码中的空缺，将解答填入答题纸的对应栏内。 【说明】 以下Java代码实现一个简单客户关系管理系统（CRM）中通过工厂（CustomerFactory ）对象来创建客户（Customer）对象的功能。客户分为创建成功的客户（RealCustomer）和空客户 （NullCustomer）。空客户对象是当不满足特定条件时创建或获取的对象。类间关系如图 5-1 所示。 图5-1 类图 【Java代码】 Abstract class Customer﹛ Protected String name; （ 1 ）boolean isNil(); （ 2 ）String getName(); ﹜ Class RealCustomer （ 3 ）Customer{ Public RealCustomer(String name){ this.name=name; } Public String getName(){ return name ; } Public boolean is Nil() { return false; } ﹜ Class NullCustomer（ 4 ）Customer﹛ Public String getName()﹛ return "Not Available in Customer Database"; ﹜ Public boolean isNil() ﹛ return true; ﹜ ﹜ class Customerfactory { public String[] names = {"Rob"，"Joe"，"Julie"}; public Customer getCustomer(String name) { for (int i = 0; i < names.length;i++) { if (names[i].（ 5 ）)﹛ return new RealCustomer(name); ﹜ ﹜ return （ 6 ）; ﹜ ﹜ Public class CrM﹛ Public viod get Customer()﹛ Customerfactory（ 7 ）; Customer customer1-cf.getCustomer("Rob"); Customer customer2=cf.getCustomer("Bob"); Customer customer3= cf.getCustomer("Julie"); Customer customer4= cf.getCustomer("Laura"); System.out.println("customers”) System.out.println(customer1.getName()); System.out.println(customer2getName()); System.out.println(customer3.getName()); System.out.println(customer4.getName()); ﹜ Public static viod main (String[]arge)﹛ CRM crm =new CRM(); Crm.getCustomer(); ﹜ ﹜ /*程序输出为： Customers rob Not Available in Customer Database Julie Not Available in Customer Database */