Hi Friend,

Try the following code:
import java.util.*;
class Books{
public String title;
public String author;
public int isbn;
public double price;
public double discount;
public double total;

public Books(){}
public Books(String title,String author, int isbn,double price,double discount,double total) {
super();
this.title=title;
this.author= author;
this.isbn = isbn;
this.price=price;
this.discount=discount;
this.total=total;
}
public String getTitle() {
return title;
}
public String getAuthor() {
return author;
}
public int getIsbn() {
return isbn;
}
public double getPrice() {
return price;
}
public double getDiscount() {
return discount;
}
public double getTotal() {
return total;
}
}
public class BookStore {
public static void main(String[] args) throws Exception {
double amount=0.0;
double sum=0.0;
int count=1;
List<Books> list = new ArrayList<Books>();
Scanner scan = new Scanner(System.in);
int menu = 0;
System.out.println("Book Store");
System.out.println();
System.out.println("1. Buy book");
System.out.println("2. Receipt");
System.out.println("3. Receive Payment");
System.out.println("4. Exit");
boolean quit = false;
do{
if(count>5){
System.out.println("You cannot buy more than 5 books at a time.");
}
System.out.print("Please enter your choice: ");
menu = scan.nextInt();
System.out.println();
switch(menu) {
case 1:
count++;
System.out.println("Book Title: ");
String booktitle = scan.next();
System.out.println("Author: ");
String auth = scan.next();
System.out.println("ISBN: ");
int no = scan.nextInt();
System.out.println("Price: ");
double p = scan.nextDouble();
System.out.println("Discount: ");
double dis = scan.nextDouble();
double total=p-(dis*p);
list.add(new Books(booktitle,auth,no,p,dis,total));
break;
case 2:
System.out.println("Title Author ISBN Price Discount Total");
for (Books s : list){
System.out.println(s.getTitle()+" " +s.getAuthor()+" " +s.getIsbn()+" "+s.getPrice()+" " +s.getDiscount()+" " +s.getTotal());
sum+=s.getTotal();
}
System.out.println("Total= "+sum);
break;
case 3:
System.out.println("Customer Pays: ");
amount = scan.nextDouble();
double balance=amount-sum;
System.out.println("Balance is: "+balance);
quit = true;
case 4:
quit = true;

break;
default:
System.out.println("Invalid Entry!");
}
}
while (!quit);
}
}

Thanks