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 */