OBJECT ORIENTED PROGRAMMING IN JAVA ‐ EXERCISES
CHAPTER 1
1. Write Text‐Based Application using Object‐Oriented Approach to display your name.
// filename: Name.java // Class containing display() method, notice the class doesnt have a main() method

public class Name { public void display() { System.out.println("Mohamed Faisal"); } }
// filename: DisplayName.java // place in same folder as the Name.java file // Class containing the main() method

public class DisplayName { public static void main(String[] args) { Name myname = new Name(); // creating a new object of Name class myname.display(); // executing the display() method in the Name class } }

2. Write a java Applet to display your age.
// filename: DisplayNameApplet.java

import java.applet.Applet; // import necessary libraries for an applet import java.awt.Graphics; public class DisplayNameApplet extends Applet { public void paint(Graphics g) { g.drawString("Mohamed Faisal", 50, 25); } }
// filename: DisplayNameApplet.htm // place in same folder as the compiled DisplayNameApplet.class file

Displaying my Name

CHAPTER 2 3. Write a program that calculates and prints the product of three integers.
// filename: Q1.java

import java.util.Scanner; // import Scanner libraries for input public class Q1 { public static void main(String[] args) { Scanner input = new Scanner (System.in); int number1; int number2; int number3; System.out.println("Enter the First Number"); www.oumstudents.tk number1 = input.nextInt(); System.out.println("Enter the Second Number"); number2 = input.nextInt(); System.out.println("Enter the Third Number"); number3 = input.nextInt(); System.out.printf("The product of three number is %d:", number1 * number2 * number3); } }

4. Write a program that converts a Fahrenheit degree to Celsius using the formula:
// filename: Q2.java

import java.util.*; public class Q2 { public static void main(String[] args) { Scanner input = new Scanner(System.in); double celsius; double tempInFahrenheit = 0.0; celsius = (tempInFahrenheit - 32.0) * 5.0 / 9.0; System.out.println("Enter the fahrenheit value"); tempInFahrenheit = input.nextDouble(); System.out.printf("The celsious value of %10.2f is %2.2f",tempInFahrenheit, celsius); } }

5. Write an application that displays the numbers 1 to 4 on the same line, with each pair of adjacent numbers separated by one space. Write the application using the following techniques: a. Use one System.out.println statement. b. Use four System.out.print statements. c. Use one System. out. printf statement.
// filename: Printing.java

public class Printing { public static void main(String[] args) { int num1 = 1; int num2 = 2; int num3 = 3; int num4 = 4; System.out.println(num1 + " " + num2 + " " + num3 + " " + num4); System.out.print(num1 + " " + num2 + " " + num3 + " " + num4); System.out.printf("\n%d %d %d %d",num1,num2,num3,num4); } }

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6. Write an application that asks the user to enter two integers, obtains them from the user and prints their sum, product, difference and quotient (division).
// File: NumberCalc1.java

import java.util.Scanner; public class NumberCalc1 {

// include scanner utility for accepting keyboard input // begin class

public static void main(String[] args) { // begin the main method Scanner input=new Scanner (System.in); //create a new Scanner object to use int num1=0, num2=0; // initialize variables System.out.printf("NUMBER CALCULATIONS\n\n"); System.out.printf("Enter First Number:\t "); num1=input.nextInt(); // store next integer in num1 System.out.printf("Enter Second Number:\t "); num2=input.nextInt(); // store next integer in num2
// display the sum, product, difference and quotient of the two numbers

System.out.printf("---------------------------\n"); System.out.printf("\tSum =\t\t %d\n", num1+num2); System.out.printf("\tProduct =\t %d\n", num1*num2); System.out.printf("\tDifference =\t %d\n", num1-num2); System.out.printf("\tQuotient =\t %d\n", num1/num2); } }

CHAPTER 3 7. Write an application that asks the user to enter two integers, obtains them from the user and displays the larger number followed by the words “is larger”. If the numbers are equal, print “These numbers are equal”
// File: Question1.java // Author: Abdulla Faris

import java.util.Scanner; public class Question1 {

// include scanner utility for accepting keyboard input

// begin class

public static void main(String[] args) { // begin the main method Scanner input=new Scanner (System.in); //create a new Scanner object to use (system.in for Keyboard inputs) int num1=0, num2=0, bigger=0;

// initialize variables

System.out.printf("Enter First Number: "); num1=input.nextInt(); // store next integer in num1 System.out.printf("Enter Second Number: "); num2=input.nextInt(); // store next integer in num2 if (num1>num2){ // checks which number is larger bigger=num1; System.out.printf("%d Is Larger", bigger); } else if (num1num2?num1:num2; // checks the biggest number in and assigns it to bigger variable bigger=bigger>num3?bigger:num3; smaller=num1 0.0) {price=prc;} else {price=0.0;} } public double getInvoiceAmount(){ return (double)quantity*price; } }

//filename: InvoiceTest.java // Invoice testing class with the main() method

public class InvoiceTest { public static void main (String args[]){ Invoice invoice1=new Invoice ("A5544", "Big Black Book", 500, 250.00); Invoice invoice2=new Invoice ("A5542", "Big Pink Book", 300, 50.00); System.out.printf("Invoice 1: %s\t%s\t%d\t$%.2f\n", invoice1.getPartNum(), invoice1.getPartDesc(), invoice1.getQuantity(), invoice1.getPrice()); System.out.printf("Invoice 2: %s\t%s\t%d\t$%.2f\n", invoice2.getPartNum(), invoice2.getPartDesc(), invoice2.getQuantity(), invoice2.getPrice()); } }

18. Create a class called Employee that includes three pieces of information as instance variables—a first name (typeString), a last name (typeString) and a monthly salary (double). Your class should have a constructor that initializes the three instance variables. Provide a set and a get method for each instance variable. If the monthly salary is not positive, set it to 0.0. Write a test application named EmployeeTest that demonstrates class Employee’s capabilities. Create two Employee objects and display each object’s yearly salary. Then give each Employee a 10% raise and display each Employee’s yearly salary again.
//filename: Employee.java // Employee class

public class Employee { private String firstName; private String lastName; private double salary; public Employee(String fName, String lName, double sal) { if (fName != null) firstName =fName; if (lName != null) lastName = lName; if (sal > 0.0) { salary=sal; } else { salary=0.0; } }
//set methods

public String getFirstName(){ return firstName; } public String getLastName(){ return lastName; } public double getSalary(){ return salary; }

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//get methods

public void setFirstName(String fName){ if (fName != null) firstName = fName; } public void setLastName(String lName){ if (lName != null) lastName = lName; } public void setSalary(double sal){ if (sal > 0.0){ salary = sal; } else { salary = 0.0; } } }

//filename: EmployeeTest.java // Employee testing class with the main() method

public class EmployeeTest { public static void main (String args[]){ Employee employee1=new Employee ("Mohamed", "Ali", 20000.00); Employee employee2=new Employee ("Ahmed", "Ibrahim", 50000.00); System.out.printf("\nNO:\t NAME\t\t\tYEARLY SALARY\n"); System.out.printf("--\t ----\t\t\t-------------\n"); System.out.printf("1:\t %s %s\t\t$%.2f\n", employee1.getFirstName(), employee1.getLastName(), employee1.getSalary()); System.out.printf("2:\t %s %s\t\t$%.2f\n", employee2.getFirstName(), employee2.getLastName(), employee2.getSalary());
//set raise 10%

employee1.setSalary( (.1*employee1.getSalary())+employee1.getSalary()); employee2.setSalary( (.1*employee2.getSalary())+employee2.getSalary()); System.out.printf("\n10 Percent Salary Raised!! Yoohooooo!\n"); System.out.printf("\nNO:\t NAME\t\t\tYEARLY SALARY\n"); System.out.printf("--\t ----\t\t\t-------------\n"); System.out.printf("1:\t %s %s\t\t$%.2f\n", employee1.getFirstName(), employee1.getLastName(), employee1.getSalary()); System.out.printf("2:\t %s %s\t\t$%.2f\n", employee2.getFirstName(), employee2.getLastName(), employee2.getSalary()); } }

19. Create a class called Date that includes three pieces of information as instance variables—a month (typeint), a day (typeint) and a year (typeint). Your class should have a constructor that initializes the three instance variables and assumes that the values provided are correct. Provide a set and a get method for each instance variable. Provide a method displayDate that displays the month, day and year separated by forward slashes(/). Write a test application named DateTest that demonstrates classDate’s capabilities.
//filename: Date.java // Date class

public class Date { private int month; private int day; private int year; public Date(int myMonth,int myDay, int myYear) { www.oumstudents.tk month = myMonth; day = myDay; year = myYear; } public void setMonthDate(int myMonth) { month = myMonth; } public int getMonthDate() { return month; } public void setDayDate(int myDay) { day = myDay; } public int getDayDate() { return month; } public void setYearDate(int myYear) { year = myYear; } public int getYearDate() { return year; } public void displayDate() { System.out.printf("%d/%d/%d", month,day,year); } }

//filename: DateTest.java // Date testing class with the main() method

import java.util.*; public class DateTest { public static void main(String[] args) { Scanner input = new Scanner(System.in); Date myDate = new Date(9, 11, 1986); System.out.println("Enter The Month"); int myMonth = input.nextInt(); myDate.setMonthDate(myMonth); System.out.println("Enter the Date"); int myDay = input.nextInt(); myDate.setDayDate(myDay); System.out.println("Enter the Year"); int myYear = input.nextInt(); myDate.setYearDate(myYear); myDate.displayDate(); } }

CHAPTER 6
20. Create class SavingsAccount. Usea static variable annualInterestRate to store the annual interest rate for all account holders. Each object of the class contains a private instance variable savingsBalance indicating the amount the saver currently has ondeposit. Provide method calculateMonthlyInterest to calculate the monthly www.oumstudents.tk interest by multiplying the savingsBalance by annualInterestRate divided by 12 this interest should be added to savingsBalance. Provide a static method modifyInterestRate that sets the annualInterestRate to a new value. Write a program to test class SavingsAccount. Instantiate two savingsAccount objects, saver1 and saver2, with balances of $2000.00 and $3000.00, respectively. Set annualInterestRate to 4%, then calculate the monthly interest and print the new balances for both savers. Then set the annualInterestRate to 5%, calculate the next month’s interest and print the new balances for both savers.
//filename: SavingAccount.java // SavingAccount class

public class SavingsAccount { public static double annualInterestRate; private double savingsBalance; public SavingsAccount() { annualInterestRate = 0.0; savingsBalance = 0.0; } public SavingsAccount(double intRate, double savBal) { annualInterestRate = intRate; savingsBalance = savBal; } public double calculateMonthlyInterest() { double intRate = (savingsBalance * annualInterestRate/12); savingsBalance = savingsBalance + intRate; return intRate; } public static void modifyInterestRate(double newInteresRate) { annualInterestRate = newInteresRate; } public void setSavingsBalance(double newBal) { savingsBalance = newBal; } public double getSavingsBalance() { return savingsBalance; } public double getAnnualInterestRate() { return annualInterestRate; } }

//filename: SavingsAccountTest.java // SavingsAccount testing class with the main() method

public class SavingsAccountTest { public static void main(String[] args) { SavingsAccount saver1 = new SavingsAccount(); SavingsAccount saver2 = new SavingsAccount(); saver1.setSavingsBalance(2000.00); saver2.setSavingsBalance(3000.00); SavingsAccount.modifyInterestRate(0.04); saver1.calculateMonthlyInterest(); saver2.calculateMonthlyInterest(); System.out.printf("New Balance for Saver1=%f\n",saver1.getSavingsBalance()); System.out.printf("New Balance for Saver2=%f\n",saver2.getSavingsBalance());

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SavingsAccount.modifyInterestRate(0.05); saver1.calculateMonthlyInterest(); saver2.calculateMonthlyInterest(); System.out.printf("New Balance for Saver1=%f\n",saver1.getSavingsBalance()); System.out.printf("New Balance for Saver2=%f\n",saver2.getSavingsBalance()); } }

21. Create a class called Book to represent a book. A Book should include four pieces of information as instance variables‐a book name, an ISBN number, an author name and a publisher. Your class should have a constructor that initializes the four instance variables. Provide a mutator method and accessor method (query method) for each instance variable. Inaddition, provide a method named getBookInfo that returns the description of the book as a String (the description should include all the information about the book). You should use this keyword in member methods and constructor. Write a test application named BookTest to create an array of object for 30 elements for class Book to demonstrate the class Book's capabilities.
//filename: Book.java // Book class

public class Book { private String Name; private String ISBN; private String Author; private String Publisher; public Book() { Name = "NULL"; ISBN = "NULL"; Author = "NULL"; Publisher = "NULL"; } public Book(String name, String isbn, String author, String publisher) { Name = name; ISBN = isbn; Author = author; Publisher = publisher; } public void setName(String Name) { this.Name = Name; } public String getName() { return Name; } public void setISBN(String ISBN) { this.ISBN = ISBN; } public String getISBN() { return ISBN; } public void setAuthor(String Author) { this.Author = Author; } public String getAuthor() { return Author; } public void setPublisher(String Publisher) { this.Publisher = Publisher; } public String getPublisher() { return Publisher; }

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public void getBookInfo() { System.out.printf("%s %s %s %s", Name,ISBN,Author,Publisher); } }

//filename: SavingsAccountTest.java // SavingsAccount testing class with the main() method

public class BookTest { public static void main(String[] args) {

Book test[] = new Book[13]; test[1] = new Book(); test[1].getBookInfo(); } }

CHAPTER 7 22. a. Create a super class called Car. The Car class has the following fields and methods. ◦intspeed; ◦doubleregularPrice; ◦Stringcolor; ◦doublegetSalePrice();
//filename: Car.java //Car class

public class Car { private int speed; private double regularPrice; private String color; public Car (int Speed,double regularPrice,String color) { this.speed = Speed; this.regularPrice = regularPrice; this.color = color; }

public double getSalePrice() { return regularPrice; } }

b. Create a sub class of Car class and name it as Truck. The Truck class has the following fields and methods. ◦intweight; ◦doublegetSalePrice();//Ifweight>2000,10%discount.Otherwise,20%discount.
//filename: Truck.java // Truck class, subclass of Car

public class Truck extends private int weight;

Car {

public Truck (int Speed,double regularPrice,String color, int weight) { super(Speed,regularPrice,color); this.weight = weight; } www.oumstudents.tk public double getSalePrice() { if (weight > 2000){ return super.getSalePrice() - (0.1 * super.getSalePrice()); } else { return super.getSalePrice(); } } }

c. Create a subclass of Car class and name it as Ford. The Ford class has the following fields and methods ◦intyear; ◦intmanufacturerDiscount; ◦doublegetSalePrice();//FromthesalepricecomputedfromCarclass,subtractthemanufacturerDiscount.
//filename: Ford.java // Ford class, subclass of Car

public class Ford extends Car { private int year; private int manufacturerDiscount; public Ford (int Speed,double regularPrice,String color, int year, int manufacturerDiscount) { super (Speed,regularPrice,color); this.year = year; this.manufacturerDiscount = manufacturerDiscount; } public double getSalePrice() { return (super.getSalePrice() - manufacturerDiscount); } }

d. Create a subclass of Car class and name it as Sedan. The Sedan class has the following fields and methods. ◦intlength; ◦doublegetSalePrice();//Iflength>20feet,5%discount,Otherwise,10%discount.
//filename: Sedan.java // Sedan class, subclass of Car

public class Sedan extends Car { private int length; public Sedan (int Speed,double regularPrice,String color, int length) { super (Speed,regularPrice,color); this.length = length; } public double getSalePrice() { if (length > 20) { return super.getSalePrice() - (0.05 * super.getSalePrice()); } else { return super.getSalePrice() - (0.1 * super.getSalePrice()); } } }

e. Create MyOwnAutoShop class which contains the main() method. Perform the following within the main() method. ◦Create an instance of Sedan class and initialize all the fields with appropriate values. Use super(...) method in the constructor for initializing the fields of the superclass. ◦Create two instances of the Ford class and initialize all the fields with appropriate values. Use super(...) method in the constructor for initializing the fields of the super class. www.oumstudents.tk ◦Create an instance of Car class and initialize all the fields with appropriate values. Display the sale prices of all instance.
//filename: MyOwnAutoShop.java // Testing class with the main() method

public class MyOwnAutoShop { (int Speed,double regularPrice,String color, int year, int manufacturerDiscount) public static void main(String[] args) { Sedan mySedan = new Sedan(160, 20000, "Red", 10); Ford myFord1 = new Ford (156,4452.0,"Black",2005, 10); Ford myFord2 = new Ford (155,5000.0,"Pink",1998, 5); Car myCar - new Car (555, 56856.0, "Red"); System.out.printf("MySedan Price %.2f", mySedan.getSalePrice()); System.out.printf("MyFord1 Price %.2f", myFord1.getSalePrice()); System.out.printf("MyFord2 Price %.2f", myFord2.getSalePrice()); System.out.printf("MyCar Price %.2f", myCar.getSalePrice()); } }

CHAPTER 8 CHAPTER 9
23. Write an applet that asks the user to enter two floating‐point numbers, obtains the two numbers from the user and draws their sum, product (multiplication), difference and quotient (division). Use the techniques shown in example.

//filename: simpleApplet1.java

import java.awt.*; import javax.swing.*; public class simpleApplet1 extends JApplet { double sum; double product; double difference; double quotient; public void init() { String firstNumber; String secondNumber; double number1; double number2; firstNumber = JOptionPane.showInputDialog("Enter the first number"); secondNumber = JOptionPane.showInputDialog("Enter the second number"); number1 = Double.parseDouble(firstNumber); number2 = Double.parseDouble(secondNumber); sum = number1 + number2; product = number1 * number2; difference = number1 - number2; quotient = number1 % number2; } public void paint(Graphics g) { www.oumstudents.tk super.paint(g); g.drawRect(15, 10, 270, 60); g.drawString("Sum "+sum, 25, 25); g.drawString("Product "+product, 25, 35); g.drawString("Difference "+difference, 25, 45); g.drawString("Quotient "+quotient, 25, 55); }

}

CHAPTER 10 24. Create an applet that can display the following component. No event handling is needed for the components.
//filename: simpleAppet2.java

import javax.swing.*; import java.awt.*; public class simpleAppet2 extends JApplet { private JLabel lblName; private JLabel lblAddress; private JLabel lblEmail; private JTextField txtName; private JTextField txtAddress; private JTextField txtEmail; public void init() { Container conpane = getContentPane(); conpane.setLayout(new FlowLayout()); lblName = new JLabel("name"); lblAddress = new JLabel("address"); lblEmail = new JLabel("email"); txtName = new JTextField(10); txtAddress = new JTextField(10); txtEmail = new JTextField(10); conpane.add(lblName); conpane.add(txtName); conpane.add(lblAddress); conpane.add(txtAddress); conpane.add(lblEmail); conpane.add(txtEmail); } }

25. Create an applet that can display the following component. No event handling is needed for the components.
//filename: simpleAppet3.java

import javax.swing.*; import java.awt.*; public class simpleAppet3 extends JApplet { private JButton button1, button2, button3, button4, button5; public void init( ){ Container conpane = getContentPane(); conpane.setLayout(new BorderLayout()); JPanel panel = new JPanel(); panel.setLayout(new GridLayout(1,5)); www.oumstudents.tk button1 button2 button3 button4 button5

= = = = =

new new new new new

JButton("Button JButton("Button JButton("Button JButton("Button JButton("Button

1"); 2"); 3"); 4"); 5");

panel.add(button1); panel.add(button2); panel.add(button3); panel.add(button4); panel.add(button5); conpane.add("South",panel); } }

CHAPTER 11 26. Temperature Conversion a. Write a temperature conversion applet that converts from Fahrenheit to Celsius. The Fahrenheit temperature should be entered from the keyboard (via a JTextField). A JLabel should be used to display the converted temperature. Use the following formula for the conversion: Celcius = ((5/9)*(Ferenheit‐32)). b. Enhance the temperature conversion applet of Q1 by adding the Kelvin temperature scale. The applet should also allow the user to make conversions between any two scales. Use the following formula for the conversion between Kelvin and Celsius (in addition to the formulain Q1): Kelvin = Celcius + 273.15
/* * Filename: tempCon.java * Author: Abdulla Faris * Date: 13/04/2010 */

import import import import

javax.swing.*; java.awt.*; java.awt.event.*; java.text.*;

public class tempCon extends JApplet implements ActionListener { JTextField txtInput; JLabel lblResult; JRadioButton rbCelcius, rbKelvin; public void init(){ Container conpane = getContentPane(); conpane.setLayout (new FlowLayout()); txtInput = new JTextField("",10); conpane.add(txtInput); rbCelcius= new JRadioButton ("to Celcius", true); conpane.add(rbCelcius); rbKelvin = new JRadioButton("to Kelvin", false); conpane.add(rbKelvin); ButtonGroup selection = new ButtonGroup(); selection.add(rbCelcius); selection.add(rbKelvin); JButton button1 = new JButton ("Show Result"); button1.addActionListener(this); conpane.add(button1); www.oumstudents.tk lblResult= new JLabel ("Enter Ferenheit, Choose an option to convert and Click Show Result"); conpane.add(lblResult); } public void actionPerformed(ActionEvent e) { DecimalFormat df = new DecimalFormat ("#.##"); double ferenheit = Double.parseDouble(txtInput.getText()); double answer = 0.0; answer = ((5.0/9.0)*(ferenheit - 32.0)); if (rbKelvin.isSelected()) answer += 273.15; lblResult.setText(String.valueOf(df.format(answer))); } }

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