开闭原则：

public interface IBook{
  public String getName();
  public int getPrice();
  public String getAuthor();

}
===================================================
小说书籍的源代码如下：
public class NovelBook implements IBook{
private String name;

private int price;

private String author;

public NovelBook(String _name,int _price,String _author){

this.name=_name;
this.price=_price;
this.author=_author;
}

public String getAuthor(){
return this.author;}

public String getName(){
return this.name;}

public int getPrice(){
return this.price;}
}

}
========================================================

销售书籍：

public class BookStore{
private final static ArrayList<IBook> bookList= new ArrayList<IBook>();

static{
bookList.add(new NovelBook("天龙八部1",3200,"金庸"))；
bookList.add(new NovelBook("天龙八部2",3200,"金庸"))；
bookList.add(new NovelBook("天龙八部3",3200,"金庸"))；
bookList.add(new NovelBook("天龙八部4",3200,"金庸"))；

}

public static void main(Sting() args){
   NumberFormat formatter=NumberFormat2.getCurrencyInstance();
   formatter.setMaximunFractionDigits(2);
    System.out.println("--------------书店买出去的书籍如下")；
   for(IBook book:bookList){

book.getName();
book.getAuthor();
book.getPrice();
}

}

}