阅读下列说明和java代码,将应填入 (n) 处的字句写在答题纸的对应栏内。

免费题库2022-08-02  7

问题 阅读下列说明和java代码,将应填入  (n)  处的字句写在答题纸的对应栏内。【说明】   某发票(lnvoice)由抬头(Head)部分、正文部分和脚注(Foot)部分构成。现采用装饰(Decorator)模式实现打印发票的功能,得到如图6-1所示的类图。【java代码】class invoice{public void printInvoice( ){           System.out.println ( "This is the content of the invoice!");    }}class Decorator extends Invoice {  protected Invoice ticket;  public Decorator(lnvoice t){        ticket = t;}   publicvoid printInvoice( ){        if(ticket != null)                          (1)       ; }  }class HeadDecorator extends Decorator{      public HeadDecorator(lnvoice t){          super(t);}    public void printInvoice ( ){           Systent.out.println( "This is the header of the invoice! ");                          (2)         ;    }} class FootDecorator extends Decorator {   public FootDecorator(Invoice t){   super(t);}    public void printlnvoice( ){                      ( 3)        ;            Systent.out.println( "This is the footnote of the invoice! ");    }}Class test {   public static void main(String[] args){    Invoice t =new Invioce( );    Invoice ticket;    ticket=     (4)       ;    ticket.printInvoice( );    Systent.out.println(“------------------“);    ticket=       (5)       ;    ticket.printInvoice( );   }}程序的输出结果为:   This is the header of the invoice!   This is the content of the invoice!   This is the footnote of the invoice!    ----------------------------   This is the header of the invoice!   This is the footnote of the invoice!

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答案

解析 (1) ticket.printInvoice()
(2) ticket.printInvoice()

(3) ticket.printInvoice()

(4) new FootDecorator(new
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