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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");
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); }
}
8. Write an application that inputs three integers from the user and displays the sum, average, product, smallest
and largest of the numbers.
// File: Question2.java // Author: Abdulla Faris import java.util.Scanner; // include scanner utility for accepting keyboard input
public class Question2 { // 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 , num3, bigger= 0 , smaller= 0 ; // initialize variables System.out.printf("NUMBER CALCULATIONS\n\n");
System.out.printf("Enter First Number:\t\t "); num1=input.nextInt(); // store next integer in num
System.out.printf("Enter Second Number:\t "); num2=input.nextInt(); // store next integer in num
System.out.printf("Enter Third Number:\t "); num3=input.nextInt(); // store next integer in num
bigger=num1>num2?num1:num2; // checks the biggest number in and assigns it to bigger variable bigger=bigger>num3?bigger:num3; smaller=num1<num2?num1:num2; // checks the smallest number in and assigns it to smaller variable smaller=smaller<num3?smaller:num3;
// display the sum, average, product, smallest and the biggest of all three numbers System.out.printf("\t-------------------------\n"); System.out.printf("\t\t\tSum =\t\t %d\n", num1+num2+num3); System.out.printf("\t\t\tAverage =\t %d\n", (num1+num2+num3)/ 3 ); System.out.printf("\t\t\tProduct =\t %d\n", num1num2num3); System.out.printf("\t\t\tBiggest =\t %d\n", bigger); System.out.printf("\t\t\tSmallest =\t %d\n", smaller); } }
9. Write an application that reads two integers, determines whether the first is a multiple of the second and print
the result. [Hint Use the remainder operator.]
// File: Question3.java // Author: Abdulla Faris import java.util.Scanner; // include scanner utility for accepting keyboard input
public class Question3 { // 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 ,k; // initialize variables
System.out.printf("Enter First Number: "); num1=input.nextInt(); // store next integer in num
System.out.printf("Enter Second Number: "); num2=input.nextInt(); // store next integer in num
k=num2%num1; // assign the remainder ofnum2 divided by num1 to the integer k
if (k== 0 ){ // check if k is 0. remainder k will be 0 if num1 is a multiple of num2, System.out.printf("%d is a multiple of %d", num1,num2); } else { System.out.printf("%d is not a multiple of %d", num1,num2); } } }
10. The process of finding the largest value (i.e., the maximum of a group of values) is used frequently in computer
applications. For example, a program that determines the winner of a sales contest would input the number of
units sold by each sales person. The sales person who sells the most units wins the contest. Write a Java
application that inputs a series of 10 integers and determines and prints the largest integer. Your program should
use at least the following three variables:
a. counter: A counter to count to 10 (i.e., to keep track of how many numbers have been input and to
determine when all 10 numbers have been processed).
b. number : The integer most recently input by the user.
c. largest: The largest number found so far.
// File: Question4.java // Author: Abdulla Faris import java.util.Scanner; // include scanner utility for accepting keyboard input
public class Question4 { // 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 counter= 0 , number= 0 , largest= 0 ; // initialize variables
for (counter= 0 ; counter< 10 ;counter++){ // loop ten times from 0 to 9 System.out.printf("Enter Number [%d]: ", counter+ 1 ); number=input.nextInt(); // store next integer in number largest=largest>number?largest:number; // check if new number is larger, if so assign it to larger }
System.out.printf("Largest = %d", largest); // display the largest value } }
11. Write a Java application that uses looping to print the following table of values:
// File: Question5.java // Author: Abdulla Faris public class Question5 { // begin class
public static void main(String[] args) { // begin the main method int counter= 1 ; // initialize variables System.out.printf("N\t10N\t100N\t1000N\n\n", counter, counter 10 , counter* 100 , counter* 1000 ); // display header for (counter= 1 ; counter<= 5 ;counter++){ // loop five times, 1 to 5 System.out.printf("%d\t%d\t%d\t%d\n", counter, counter* 10 , counter* 100 , counter* 1000 ); // display the table of values } } }
12. Write a complete Java application to prompt the user for the double radius of a sphere, and call method
sphereVolumeto calculate and display the volume of the sphere. Use the following statement to calculate the
volume:
// File: Question6.java // Author: Abdulla Faris
import java.util.Scanner; // include scanner utility for accepting keyboard input
String str; //declaring a string variable str System.out.printf("Enter String: "); str=input.nextLine();// store next line in str
// display the same string in both uppercase and lowercase System.out.printf("%s%s",str.toUpperCase(),str.toLowerCase()); } }
15. Write a Java application that allows the user to enter up to 20 integer grades into an array. Stop the loop by
typing in ‐1. Your main method should call an Average method that returns the average of the grades. Use the
DecimalFormat class to format the average to 2 decimal places.
// File: Question3.java // Author: Abdulla Faris
import java.util.Scanner; // include scanner utility for accepting input
public class Question3 {// begin class
public static double Average(int grades[], int max ) {// begin Average method int sum= 0 ; // initialize variables double average=0.0;
for (int i= 1 ;i<max;i++){ // loop and calculate the Average sum+=grades[i]; average=sum/(i); }
return average; // return the average after calculation
}
public static void main(String[] args) {// begin the main method
Scanner input=new Scanner(System.in); //create a new Scanner object to use
int i, grades[]; // initialize variables grades=new int[ 20 ];
for (i= 0 ;i< 20 ;i++){ // start to loop 20 times System.out.printf("Enter Grade: "); grades[i]=input.nextInt();// store next integer in grades[i] if (grades[i]==- 1 ) break; }
System.out.printf("%.2f", Average(grades, i- 1 )); } }
CHAPTER 5
16. Modify class Account (in the example) to provide a method called debit that withdraws money froman Account.
Ensure that the debit amount does not exceed the Account’s balance. If it does, the balance should be left
unchanged and the method should print a message indicating ―Debit amount exceeded account balance.
Modify class AccountTest (intheexample) to test method debit.
//filename: Account.java // Accout class public class Account { private double balance;
public Account(double initialBalance) {
if (initialBalance > 0.0) balance=initialBalance; }
public void credit(double amount){ balance=balance+amount; }
public void debit(double amount){ balance=balance-amount;
}
public double getBalance(){ return balance; } }
//filename: AccountTest.java // Accout testing class with the main() method
import java.util.Scanner;
public class AccountTest {
public static void main (String args[]){ Account account1 = new Account (50.00); Account account2 = new Account (-7.53);
System.out.printf("Account1 Balance: $%.2f\n", account1.getBalance()); System.out.printf("Account2 Balance: $%.2f\n\n", account2.getBalance());
Scanner input = new Scanner( System.in ); double depositAmount; double debitAmount;
System.out.print( "Enter deposit amount for account1: " ); // prompt depositAmount = input.nextDouble(); // obtain user input System.out.printf( "\nadding %.2f to account1 balance\n\n", depositAmount ); account1.credit( depositAmount ); // add to account1 balance
// display balances System.out.printf( "Account1 balance: $%.2f\n", account1.getBalance() ); System.out.printf( "Account2 balance: $%.2f\n\n", account2.getBalance() );
System.out.print( "Enter deposit amount for account2: " ); // prompt depositAmount = input.nextDouble(); // obtain user input System.out.printf( "\nAdding %.2f to account2 balance\n\n", depositAmount ); account2.credit( depositAmount ); // add to account2 balance
// display balances System.out.printf( "Account1 balance: $%.2f\n", account1.getBalance() ); System.out.printf( "Account2 balance: $%.2f\n", account2.getBalance() );
System.out.print( "Enter debit amount for account1: " ); debitAmount = input.nextDouble(); System.out.printf( "\nSubtracting %.2f from account1 balance\n\n", debitAmount ); if (account1.getBalance()>=debitAmount) { account1.debit( debitAmount ); System.out.printf( "Account1 balance: $%.2f\n", account1.getBalance() ); System.out.printf( "Account2 balance: $%.2f\n\n", account2.getBalance() ); } else { System.out.printf("!!! Debit amount exceeded account balance!!!\n\n"); }
public void setQuantity(int qty){ if (qty > 0 ) {quantity=qty;} else {quantity= 0 ;} }
public void setPrice(double prc){ if (prc > 0.0) {price=prc;} else {price=0.0;} }
public double getInvoiceAmount(){ return (double)quantity*price; } }
//filename: InvoiceTest.java // Invoice testing class with the main() method
public class InvoiceTest { public static void main (String args[]){ Invoice invoice1=new Invoice ("A5544", "Big Black Book", 500 , 250.00); Invoice invoice2=new Invoice ("A5542", "Big Pink Book", 300 , 50.00);
System.out.printf("Invoice 1: %s\t%s\t%d\t$%.2f\n", invoice1.getPartNum(), invoice1.getPartDesc(), invoice1.getQuantity(), invoice1.getPrice()); System.out.printf("Invoice 2: %s\t%s\t%d\t$%.2f\n", invoice2.getPartNum(), invoice2.getPartDesc(), invoice2.getQuantity(), invoice2.getPrice()); } }
18. Create a class called Employee that includes three pieces of information as instance variables—a first name
(typeString), a last name (typeString) and a monthly salary (double). Your class should have a constructor that
initializes the three instance variables. Provide a set and a get method for each instance variable. If the monthly
salary is not positive, set it to 0.0. Write a test application named EmployeeTest that demonstrates class
Employee’s capabilities. Create two Employee objects and display each object’s yearly salary. Then give each
Employee a 10% raise and display each Employee’s yearly salary again.
//filename: Employee.java // Employee class public class Employee { private String firstName; private String lastName; private double salary;
public Employee(String fName, String lName, double sal) { if (fName != null) firstName =fName; if (lName != null) lastName = lName; if (sal > 0.0) { salary=sal; } else { salary=0.0; } } //set methods public String getFirstName(){ return firstName; } public String getLastName(){ return lastName; } public double getSalary(){ return salary; }
//get methods public void setFirstName(String fName){ if (fName != null) firstName = fName; }
public void setLastName(String lName){ if (lName != null) lastName = lName; }
public void setSalary(double sal){ if (sal > 0.0){ salary = sal; } else { salary = 0.0; } }
}
//filename: EmployeeTest.java // Employee testing class with the main() method
public class EmployeeTest {
public static void main (String args[]){ Employee employee1=new Employee ("Mohamed", "Ali", 20000.00); Employee employee2=new Employee ("Ahmed", "Ibrahim", 50000.00);
System.out.printf("\nNO:\t NAME\t\t\tYEARLY SALARY\n"); System.out.printf("--\t ----\t\t\t-------------\n"); System.out.printf("1:\t %s %s\t\t$%.2f\n", employee1.getFirstName(), employee1.getLastName(), employee1.getSalary()); System.out.printf("2:\t %s %s\t\t$%.2f\n", employee2.getFirstName(), employee2.getLastName(), employee2.getSalary());
//set raise 10% employee1.setSalary( (.1employee1.getSalary())+employee1.getSalary()); employee2.setSalary( (.1employee2.getSalary())+employee2.getSalary());
System.out.printf("\n10 Percent Salary Raised!! Yoohooooo!\n"); System.out.printf("\nNO:\t NAME\t\t\tYEARLY SALARY\n"); System.out.printf("--\t ----\t\t\t-------------\n"); System.out.printf("1:\t %s %s\t\t$%.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) {
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());
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; }
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.
◦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) {
button1 = new JButton("Button 1"); button2 = new JButton("Button 2"); button3 = new JButton("Button 3"); button4 = new JButton("Button 4"); button5 = new JButton("Button 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.
/*
- Filename: tempCon.java
- Author: Abdulla Faris
- Date: 13/04/ */
import javax.swing.; import java.awt.; import java.awt.event.; import 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);
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)));
} }
