Object Oriented Programming (OOP) LAB # 3

1. Object Oriented Programming (OOP)LAB # 3 TA. Maram & TA. Mubaraka TA. Kholood & TA. Aamal

2. JOptionPane • JOptionPane is an easy way to do dialog boxes, messages or inputs. You have to import it at the beginning of the program: • Java:import javax.swing.JOptionPane;

3. The arguments for JOptionPane • for a simple message box: Java:JOptionPane.showMessageDialog (    null, "Put your message here" ); • to show text in different rows: JOptionPane.showMessageDialog (    null, "Put \nyour \nmessage \nhere" ); • the \n switches to next line

4. The arguments for JOptionPane • An example of using the simple message box

5. The arguments for JOptionPane • To show different messages with different icons, you'll need 4 arguments instead of 2. • Java:JOptionPane.showMessageDialog ( null, "Messagehere", "Title here", JOptionPane.IconName); • There are different kinds of icons for a dialog box, just replace the last argument:

6. The arguments for JOptionPane • You can also use JOptionPane for dialog boxes for input, and assign them to variables, just put: • Java:name=   // The variable JOptionPane.showInputDialog ( "put your message here" ); • Notice that the variable here is String and you can convert it to integer as the following: • int x=Integer.parseInt(name); • note: after using JOptionPane, Dontforget to exit System.exit(0);

7. Example#1 • Using JOptionPane, Write a program that asks a user to insert two numbers and displays the summation of them.

8. More Exercises on Java

9. Exercise #1 • Develop a Java application that will determine whether a department-store customer has exceeded the credit limit on a charge account. For each customer, the following facts are available: • a) account number, • b) balance at the beginning of the month, • c) total of all items charged by the customer this month, • d) total of all credits applied to the customer’s account this month and • e) allowed credit limit. • The program should input each of these facts from input dialogs as integers, calculate the new balance (= beginning balance + charges – credits), display the new balance and determine whether the new balance exceeds the customer’s credit limit. For those customers whose credit limit is exceeded, the program should display the message “Credit limit exceeded.”

10. Solution#1

11. Testing #1

12. Exercise #2 • A palindrome is a sequence of characters that reads the same backward as forward. For example, each of the following five-digit integers is a palindrome: 12321, 55555, 45554 and 11611. Write an application that reads in a five-digit integer and determines whether it is a palindrome. If the number is not five digits long, display an error message dialog indicating the problem to the user. When the user dismisses the error dialog, allow the user to enter a new value.

13. Solution #2

14. Testing #2

15. Exercise#3 (Homework) • A company wants to transmit data over the telephone, but is concerned that its phones may be tapped. It has asked you to write a program that will encrypt its data so that the data may be transmitted more securely. All of its data is transmitted as four-digit integers. Your application should read a four-digit integer entered by the user in an input dialog and encrypt it as follows: Replace each digit with the result of adding 7 to the digit and getting the remainder after dividing the new value by 10. Then swap the first digit with the third, and swap the second digit with the fourth. Then print the encrypted integer. Write a separate application that inputs an encrypted four-digit integer and decrypts it to form the original number.