使用类重新排列代码？

Question

我目前正在处理一个分配给我的项目，我在尝试找出应该如何开始时遇到了一些麻烦。这个任务是使用类重写一个程序，而不是只是把所有东西都放到主程序中。这是我创建的必须重写的代码：

public class Lab14 {
public static void main(String[] args)  {
int Numbook1=0;
int Numbook2=0;
int Numbook3=0;
double priceOfDesignPatterns=32.46;
double priceOfEffectiveJava=35.48;
double priceOfJavaPuzzlers=27.86;
String book1="Design Patterns";
String book2="Effective Java";
String book3="Java Puzzlers";
final double SALES_TAX=.065;
String choice;
int finished=0;


Scanner input=new Scanner(System.in);
System.out.println("Welcome to ECommerce!");
System.out.println("The books we have in stock are: ");
System.out.println(book1+", "+book2+", "+book3);
System.out.println("Please enter the name of the book you wish to purchase.  Press 'q' to quit.");

while (finished==0) 
{
choice=input.nextLine();
    if (choice.equals(book1))   
    {
        System.out.println("How many "+book1+"(s) do you wish to buy?");
        Numbook1=(input.nextInt())+Numbook1;
        System.out.println(Numbook1+" copies of "+book1+" are in your cart.");
        System.out.println("Enter the name of the next book you would like to purchase, or press 'q' to quit.");
    }
    else if (choice.equals(book2))
    {
        System.out.println("How many "+book2+"(s) do you wish to buy?");
        Numbook2=(input.nextInt())+Numbook2;
        System.out.println(Numbook2+" copies of "+book2+" are in your cart.");
        System.out.println("Enter the name of the next book you would like to purchase, or press 'q' to quit.");
    }
    if (choice.equals(book3))
    {
        System.out.println("How many "+book3+"(s) do you wish to buy?");
        Numbook3=(input.nextInt())+Numbook3;
        System.out.println(Numbook3+" copies of "+book3+" are in your cart.");
        System.out.println("Enter the name of the next book you would like to purchase, or press 'q' to quit.");
    }
    if (choice.equals("q"))
    {
        double total=0;
        double totalTax=0;

        total=(Numbook1*priceOfDesignPatterns)+(Numbook2*priceOfEffectiveJava)+(Numbook3*priceOfJavaPuzzlers);
        totalTax=total*SALES_TAX;
        System.out.println("Your cart contains: ");
        System.out.println(Numbook1+" "+book1+"(s), "+Numbook2+" "+book2+"(s), "+Numbook3+" "+book3+"(s).");
        System.out.println("Sales Tax: $"+totalTax);
        System.out.println("Your total cost is: $"+(totalTax+total));
        finished=1;
    }
}
}
}

现在我知道我必须编写几个类来构建book1,2,3并设置价格并在以后访问它们，但我真的迷失了如何启动流程并将所有内容汇总在一起。如果有人能指导我朝着正确的方向前进，我们将不胜感激！非常感谢你。