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 Jave 代码实现一个简单客户关系管理系统（CrM）中通过工厂（Customerrfactory ）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。

【Java 代码】
Abstract class Customer﹛
Protected String name;
( )boolean isNil( )
( )String getName( );
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Class realCustomer ( )Customer﹛
Public realCustomer（String name ）﹛ return false; ﹜
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Class NullCustomer( )Customer﹛
Public String getName( )﹛ return ″Not Available in Customer Database″; ﹜
Public boolean isNil( )﹛ return true; ﹜
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class Customerfactory {
public String[] names = {"rob"，"Joe"，"Julie"};
public Customer getCustomer（String name） {
for （int i = 0; i < names.length;i++） {
if （names[i].( )）﹛
return new realCusωmer（name）;
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return ( )
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Public class CrM﹛
Public viod get Customer( )﹛
Customerfactory( )
Customer customer1-cf.getCustomer（″rob″）;
Customer customer2=cf.getCustomer（″rob″）;
Customer customer3= cf.getCustomer（″Julie″）;
Customer customer4= cf.getCustomer（″Laura″）;
System.out.println（″customer1.getName( )）;
System.out.println（″customer2getName( )）;
System.out.println（″customer3.getName( )）;
System.out.println（″customer4.getName( )）;
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Public static viod main （String[]arge）﹛
CrM crm =new CrM( );
Crm,getCustomer( );
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／*程序输出为：
Customer
rob
Not Available in Customer Database
Julie
Not Available in Customer Datable
*／
int main( )﹛
CrM*crs=newCrM( );
Crs->getCustomer( );
Crs->getCustomer( );
Delete crs;
return( );
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／*程序输出为：
Customer
rob
Not Available ini Customer Database
Julie
Not Available in Customer Database