Lab Assignment 2
SUBJECT: OBJECT ORIENTED
PROGRAMMING
SUBMITTED TO:
Miss Arubah Hussain
SUBMITTED BY:
Mahad Khan
REGISTRATION NO:
FA23-BCS-003
Question 1:
class BeerSong {
int bottle;
public BeerSong (int bottle){
if (bottle<0){
System.out.println("Zero Bottles of Beer On The Wall");
else if (bottle >99){
this.bottle=99;
else{
this.bottle=bottle;
public void printSong(){
for ( int i=bottle;i>=0;i--){
System.out.println(convertNumberToWords(i)+" Bottles of the Beer on the
wall");
System.out.println(convertNumberToWords(i)+" Bottles of the beer");
System.out.println(" take one down pass it round");
System.out.println(convertNumberToWords(i-1)+" bottle on the wall");
}
}
private String convertNumberToWords(int n) {
String[] belowTwenty = {"Zero", "One", "Two", "Three", "Four", "Five", "Six",
"Seven", "Eight", "Nine", "Ten",
"Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen",
"Seventeen", "Eighteen", "Nineteen"};
String[] tens = {"", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy",
"Eighty", "Ninety"};
if (n < 20) {
return belowTwenty[n]; // Direct lookup for numbers less than 20
} else {
int tenVal = n / 10; // Get the tens place
int unitVal = n % 10; // Get the unit place
if (unitVal == 0) {
return tens[tenVal]; // If the unit is 0, return only the tens word
} else {
return tens[tenVal] + "-" + belowTwenty[unitVal]; // Combine tens and unit
for numbers like "Ninety-nine"
class q1{
public static void main(String[] args) {
BeerSong b = new BeerSong(99);
b.printSong();
Question 2:
package com.mycompany.rational;
public class Rational {
private int numerator;
private int denominator;
public Rational(int numerator, int denominator) {
this.numerator = numerator;
setDenominator(denominator);
}
public void setNumerator(int numerator) {
this.numerator = numerator;
}
public void setDenominator(int denominator) {
if (denominator != 0) {
this.denominator = denominator;
} else {
throw new IllegalArgumentException("Denominator cannot be zero.");
}
}
// Method to reduce fraction
public void reduce() {
int gcd = gcd(numerator, denominator);
numerator /= gcd;
denominator /= gcd;
}
// Greatest Common Divisor (GCD)
private int gcd(int a, int b) {
if (b == 0) {
return a;
}
return gcd(b, a % b);
}
@Override
public String toString() {
return numerator + "/" + denominator;
}
public static void main(String[] args) {
Rational fraction = new Rational(20, 60);
System.out.println("Before Reduction: " + fraction);
fraction.reduce();
System.out.println("After Reduction: " + fraction);
}
}
Question 4:
package blogentry;
import java.util.Date;
import java.text.SimpleDateFormat;
public class BlogEntry {
// Instance variables
private String username;
private String text;
private Date date;
// Constructor to initialize the username, text, and date of the blog
entry
public BlogEntry(String username, String text) {
this.username = username;
this.text = text;
this.date = new Date(); // Sets the current date and time
// Method to display all instance variables (username, text, date)
public void displayEntry() {
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-
MM-dd HH:mm:ss");
System.out.println("Username: " + username);
System.out.println("Date: " + dateFormat.format(date));
System.out.println("Entry: " + text);
// Method to get the first 10 words from the text (or the entire text if
it's less than 10 words)
public String getSummary() {
String[] words = text.split("\\s+"); // Split the text into words by
spaces
if (words.length <= 10) {
return text; // Return the entire text if it has 10 words or less
} else {
StringBuilder summary = new StringBuilder();
for (int i = 0; i < 10; i++) {
summary.append(words[i]).append(" ");
return summary.toString().trim() + "..."; // Add "..." at the end
for longer summaries
}
// Main method to test the BlogEntry class
public static void main(String[] args) {
// Create a BlogEntry object
BlogEntry entry = new BlogEntry("JohnDoe", "This is a sample blog
entry that demonstrates the use of the BlogEntry class in Java.");
// Display the full blog entry
System.out.println("Displaying full entry:");
entry.displayEntry();
// Display the summary of the blog entry
System.out.println("\nDisplaying summary:");
System.out.println(entry.getSummary());
Question 5:
class Counter {
private int count; // Variable to store the count value
// Constructor to initialize the counter to 0
public Counter() {
this.count = 0;
// Method to reset the counter to 0
public void reset() {
this.count = 0;
// Method to increase the counter by 1
public void increase() {
count++;
// Method to decrease the counter by 1 but not below 0
public void decrease() {
if (count > 0) {
count--;
} else {
System.out.println("Count is already zero, can't go negative.");
}
// Accessor method to return the current count
public int getCount() {
return count;
// Method to print the current count value
public void display() {
System.out.println("Current count is: " + count);
// Override toString method to provide a string representation of the
object
@Override
public String toString() {
return "Counter [count=" + count + "]";
}
// Override equals method to compare two Counter objects
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj == null || getClass() != obj.getClass()) return false;
Counter counter = (Counter) obj;
return count == counter.count;
// Main method to test the class methods
public static void main(String[] args) {
Counter counter1 = new Counter();
Counter counter2 = new Counter();
counter1.increase();
counter1.increase();
counter1.display(); // Should display 2
counter1.decrease();
counter1.display(); // Should display 1
System.out.println(counter1); // Should print Counter [count=1]
counter1.reset();
counter1.display(); // Should display 0
// Check if counter1 equals counter2 (both should be 0 at this
point)
System.out.println("Are both counters equal? " +
counter1.equals(counter2)); // Should print true
Question 7:
public class Temperature {
private double temperature;
private char scale;
public Temperature() {
this.temperature = 0.0;
this.scale = 'C';
public Temperature(double temperature) {
this.temperature = temperature;
this.scale = 'C';
public Temperature(double temperature, char scale) {
this.temperature = temperature;
this.scale = Character.toUpperCase(scale);
public double getCelsius() {
if (scale == 'C') {
return round(temperature);
} else {
return round((temperature - 32) * 5.0 / 9.0);
public double getFahrenheit() {
if (scale == 'F') {
return round(temperature);
} else {
return round(temperature * 9.0 / 5.0 + 32);
}
}
public void setTemperature(double temperature) {
this.temperature = temperature;
public void setScale(char scale) {
this.scale = Character.toUpperCase(scale);
public void setTemperature(double temperature, char scale) {
this.temperature = temperature;
this.scale = Character.toUpperCase(scale);
public boolean equals(Temperature other) {
return this.getCelsius() == other.getCelsius();
public boolean isGreaterThan(Temperature other) {
return this.getCelsius() > other.getCelsius();
public boolean isLessThan(Temperature other) {
return this.getCelsius() < other.getCelsius();
@Override
public String toString() {
return String.format("%.1f degrees %s", temperature, scale);
private double round(double value) {
return Math.round(value * 10.0) / 10.0;
public static void main(String[] args) {
Temperature temp1 = new Temperature();
Temperature temp2 = new Temperature(32.0, 'F');
Temperature temp3 = new Temperature(0.0, 'C');
Temperature temp4 = new Temperature(-40.0, 'C');
Temperature temp5 = new Temperature(100.0, 'C');
System.out.println("Temp 1: " + temp1);
System.out.println("Temp 2: " + temp2);
System.out.println("Temp 3: " + temp3);
System.out.println("Temp 4: " + temp4);
System.out.println("Temp 5: " + temp5);
System.out.println("Temp 1 equals Temp 2? " + temp1.equals(temp2));
System.out.println("Temp 4 equals Temp 2? " + temp4.equals(temp2));
System.out.println("Temp 5 equals 212.0 F? " + temp5.equals(new
Temperature(212.0, 'F')));
System.out.println("Temp 5 is greater than Temp 3? " +
temp5.isGreaterThan(temp3));
System.out.println("Temp 3 is greater than Temp 1? " +
temp3.isGreaterThan(temp1));
System.out.println("Temp 1 is less than Temp 2? " +
temp1.isLessThan(temp2));
System.out.println("Temp 4 is less than Temp 3? " +
temp4.isLessThan(temp3));
Question 8:
import java.util.Scanner;
public class Date {
private int month;
private int day;
private int year;
public Date() {
month = 1; // January
day = 1;
year = 1000;
public Date(int monthInt, int day, int year) {
setDate(monthInt, day, year);
public Date(String monthString, int day, int year) {
setDate(monthString, day, year);
public Date(int year) {
setDate(1, 1, year);
}
public Date(Date aDate) {
if (aDate == null) {
System.out.println("Fatal Error.");
System.exit(0);
this.month = aDate.month;
this.day = aDate.day;
this.year = aDate.year;
public void setDate(int monthInt, int day, int year) {
if (dateOK(monthInt, day, year)) {
this.month = monthInt;
this.day = day;
this.year = year;
} else {
System.out.println("Fatal Error");
System.exit(0);
public void setDate(String monthString, int day, int year) {
int monthInt = monthStringToInt(monthString);
setDate(monthInt, day, year);
public void setYear(int year) {
if (year >= 1000 && year <= 9999) {
this.year = year;
} else {
System.out.println("Fatal Error");
System.exit(0);
}
public void setMonth(int monthNumber) {
if (monthNumber >= 1 && monthNumber <= 12) {
this.month = monthNumber;
} else {
System.out.println("Fatal Error");
System.exit(0);
public void setDay(int day) {
if (day >= 1 && day <= 31) {
this.day = day;
} else {
System.out.println("Fatal Error");
System.exit(0);
(as int)
public int getMonth() {
return month;
public int getDay() {
return day;
public int getYear() {
return year;
public String toString() {
return monthIntToString(month) + " " + day + ", " + year;
private boolean dateOK(int monthInt, int dayInt, int yearInt) {
return (monthInt >= 1 && monthInt <= 12) &&
(dayInt >= 1 && dayInt <= 31) &&
(yearInt >= 1000 && yearInt <= 9999);
}
private boolean dateOK(String monthString, int dayInt, int yearInt)
{
int monthInt = monthStringToInt(monthString);
return dateOK(monthInt, dayInt, yearInt);
private int monthStringToInt(String month) {
switch (month.toLowerCase()) {
case "january": return 1;
case "february": return 2;
case "march": return 3;
case "april": return 4;
case "may": return 5;
case "june": return 6;
case "july": return 7;
case "august": return 8;
case "september": return 9;
case "october": return 10;
case "november": return 11;
case "december": return 12;
default:
System.out.println("Fatal Error");
System.exit(0);
return 0; // Should never reach here
private String monthIntToString(int monthInt) {
switch (monthInt) {
case 1: return "January";
case 2: return "February";
case 3: return "March";
case 4: return "April";
case 5: return "May";
case 6: return "June";
case 7: return "July";
case 8: return "August";
case 9: return "September";
case 10: return "October";
case 11: return "November";
case 12: return "December";
default:
System.out.println("Fatal Error");
System.exit(0);
return "Error"; // Should never reach here
public static void main(String[] args) {
Date date1 = new Date(2, 29, 2020);
System.out.println("Date1: " + date1);
Date date2 = new Date("March", 15, 2021);
System.out.println("Date2: " + date2);
Date date3 = new Date(2022);
System.out.println("Date3: " + date3);
Date date4 = new Date(date1);
System.out.println("Copy of Date1: " + date4);
Question 9:
public class AnimalSpecies {
private String speciesName;
private int population;
private double growthRate;
public AnimalSpecies() {
this.speciesName = "Unknown";
this.population = 0;
this.growthRate = 0.0;
public AnimalSpecies(String speciesName, int population, double growthRate) {
this.speciesName = speciesName;
this.population = population;
this.growthRate = growthRate;
}
public String getSpeciesName() {
return speciesName;
public int getPopulation() {
return population;
public double getGrowthRate() {
return growthRate;
public void setSpeciesName(String speciesName) {
this.speciesName = speciesName;
public void setPopulation(int population) {
this.population = population;
public void setGrowthRate(double growthRate) {
this.growthRate = growthRate;
}
public boolean endangered() {
return growthRate < 0;
@Override
public String toString() {
return String.format("Species: %s, Population: %d, Growth Rate: %.2f%%",
speciesName, population, growthRate);
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj == null || getClass() != obj.getClass()) return false;
AnimalSpecies other = (AnimalSpecies) obj;
return speciesName.equals(other.speciesName) && population ==
other.population && Double.compare(growthRate, other.growthRate) == 0;
public static void main(String[] args) {
AnimalSpecies species1 = new AnimalSpecies("Tiger", 3200, -2.5);
AnimalSpecies species2 = new AnimalSpecies("Elephant", 60000, 1.2);
AnimalSpecies species3 = new AnimalSpecies("Panda", 1864, 0.0);
AnimalSpecies species4 = new AnimalSpecies("Tiger", 3200, -2.5);
System.out.println(species1);
System.out.println(species2);
System.out.println(species3);
System.out.println("Is " + species1.getSpeciesName() + " endangered? " +
species1.endangered());
System.out.println("Is " + species2.getSpeciesName() + " endangered? " +
species2.endangered());
System.out.println("Is " + species3.getSpeciesName() + " endangered? " +
species3.endangered());
System.out.println("Is species1 equal to species4? " +
species1.equals(species4));
System.out.println("Is species1 equal to species2? " +
species1.equals(species2));
species1.setPopulation(3100);
species1.setGrowthRate(-1.0);
System.out.println("Updated species1: " + species1);
Question 10:
class AnimalSpecies {
private String speciesName;
private int population;
private double growthRate;
public AnimalSpecies(String speciesName, int population, double
growthRate) {
this.speciesName = speciesName;
this.population = population;
this.growthRate = growthRate;
public String getSpeciesName() {
return speciesName;
public void setSpeciesName(String speciesName) {
this.speciesName = speciesName;
}
public int getPopulation() {
return population;
public void setPopulation(int population) {
this.population = population;
public double getGrowthRate() {
return growthRate;
public void setGrowthRate(double growthRate) {
this.growthRate = growthRate;
public boolean isEndangered() {
return growthRate < 0;
}
@Override
public String toString() {
return "AnimalSpecies{" +
"speciesName='" + speciesName + '\'' +
", population=" + population +
", growthRate=" + growthRate +
'}';
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
AnimalSpecies that = (AnimalSpecies) o;
return population == that.population &&
Double.compare(that.growthRate, growthRate) == 0 &&
Objects.equals(speciesName, that.speciesName);
public class AnimalSpeciesTest {
public static void main(String[] args) {
AnimalSpecies tiger = new AnimalSpecies("Tiger", 5000, -2.5);
AnimalSpecies elephant = new AnimalSpecies("Elephant", 10000,
1.5);
System.out.println(tiger.isEndangered()); // Output: true
System.out.println(elephant.isEndangered()); // Output: false
System.out.println(tiger.toString());
System.out.println(elephant.toString());
Question 11:
public class Pizza {
private String size;
private int cheeseToppings;
private int pepperoniToppings;
private int hamToppings;
public Pizza(String size, int cheeseToppings, int pepperoniToppings, int
hamToppings) {
setSize(size);
this.cheeseToppings = cheeseToppings;
this.pepperoniToppings = pepperoniToppings;
this.hamToppings = hamToppings;
public void setSize(String size) {
if (size.equalsIgnoreCase("small") || size.equalsIgnoreCase("medium") ||
size.equalsIgnoreCase("large")) {
this.size = size;
} else {
throw new IllegalArgumentException("Size must be small, medium, or
large.");
public String getSize() {
return size;
public int getCheeseToppings() {
return cheeseToppings;
}
public int getPepperoniToppings() {
return pepperoniToppings;
public int getHamToppings() {
return hamToppings;
public double calcCost() {
double baseCost;
switch (size.toLowerCase()) {
case "small":
baseCost = 10.0;
break;
case "medium":
baseCost = 12.0;
break;
case "large":
baseCost = 14.0;
break;
default:
baseCost = 0.0;
return baseCost + 2 * (cheeseToppings + pepperoniToppings + hamToppings);
public String getDescription() {
return String.format("Size: %s, Cheese Toppings: %d, Pepperoni Toppings:
%d, Ham Toppings: %d, Total Cost: $%.2f",
size, cheeseToppings, pepperoniToppings, hamToppings, calcCost());
public static void main(String[] args) {
Pizza pizza1 = new Pizza("large", 1, 1, 2);
Pizza pizza2 = new Pizza("medium", 2, 0, 1);
Pizza pizza3 = new Pizza("small", 0, 2, 3);
System.out.println(pizza1.getDescription());
System.out.println(pizza2.getDescription());
System.out.println(pizza3.getDescription());
Question 12:
package com.mycompany.pizza;
public class PizzaOrder {
private Pizza pizza1;
private Pizza pizza2;
private Pizza pizza3;
private int numPizzas;
public void setNumPizzas(int numPizzas) {
if (numPizzas < 1 || numPizzas > 3) {
throw new IllegalArgumentException("Number of pizzas must be
between 1 and 3.");
this.numPizzas = numPizzas;
// Methods to set pizzas
public void setPizza1(Pizza pizza1) {
this.pizza1 = pizza1;
public void setPizza2(Pizza pizza2) {
this.pizza2 = pizza2;
}
public void setPizza3(Pizza pizza3) {
this.pizza3 = pizza3;
// Method to calculate total cost
public double calcTotal() {
double total = 0;
if (numPizzas >= 1) total += pizza1.calcCost();
if (numPizzas >= 2) total += pizza2.calcCost();
if (numPizzas == 3) total += pizza3.calcCost();
return total;
// Main method to test the PizzaOrder class
public static void main(String[] args) {
Pizza pizza1 = new Pizza("Large", 2, 3, 1);
Pizza pizza2 = new Pizza("Medium", 1, 0, 2);
Pizza pizza3 = new Pizza("Small", 0, 1, 0);
PizzaOrder order = new PizzaOrder();
order.setNumPizzas(3);
order.setPizza1(pizza1);
order.setPizza2(pizza2);
order.setPizza3(pizza3);
double total = order.calcTotal();
System.out.println("Total order cost: $" + total);
public class PizzaTest {
public static void main(String[] args) {
Pizza pizza1 = new Pizza("Large", 2, 3, 1); // Large pizza with 2
cheese, 3 pepperoni, and 1 ham
Pizza pizza2 = new Pizza("Medium", 1, 0, 2); // Medium pizza with 1
cheese, 0 pepperoni, and 2 ham
Pizza pizza3 = new Pizza("Small", 0, 1, 0); // Small pizza with 0
cheese, 1 pepperoni, and 0 ham
PizzaOrder order = new PizzaOrder();
order.setNumPizzas(3);
order.setPizza1(pizza1);
order.setPizza2(pizza2);
order.setPizza3(pizza3);
System.out.println(pizza1.getDescription());
System.out.println(pizza2.getDescription());
System.out.println(pizza3.getDescription());
// Calculate the total cost
double total = order.calcTotal();
System.out.println("Total order cost: $" + total);
