The question
Cik Mat operates bookstore. During their promotion period, there are books which are sold with special discounts, while others are sold at normal price. Write a program which simulates a point-of-sale (POS) system.

Customers buy books. To simplify, you may want to limit that a customer can buy only a maximum of 5 books for each transaction. However, the program will be better if a customer can buy and pay for...

Write a program that creates a simple calculator . The user enters two numbers in the text fields, Number 1 and Number 2. There are 4 buttons, labeled with “Add”, “Substract”, “Multiply” and “Divide”. When the user clicks any one buttons, the result of the operations to the two integers will be displayed in the Result text field. The program handles two kinds of exceptions:
• NumberFormatExc eption if Number 1 or Number...