Week 2 of OOP in JAVA

March 29, 2026

Week 2 of OOP in JAVA

Create a class Complex with data members real and imaginary. Use a parameterized constructor to initialize the values. Create a method to add two complex numbers and display the result in the form a + bi. Create objects in the main() method and demonstrate addition.


class Complex{
  double real;
  double imaginary;

Complex(double a,double b){
    real = a;
    imaginary = b;
  }
void addComplex(Complex z1, Complex z2){
System.out.printf("%.1f+%.1fi",z1.real+z2.real,z1.imaginary+z2.imaginary);
 }
}

public class ComplexNo {
  public static void main(String[] args){
    Complex z1 = new Complex(12.4,5.6);
    Complex z2 = new Complex(8.4,6.6);
    z1.addComplex(z1,z2);
  }
}

Create a class Date with data members day, month, and year. Use a constructor to initialize the date. Write a method to display the date in dd/mm/yyyy format. Validate whether the date entered is valid or not.


class Date{
  int dd,mm,yyyy;
  Date(int day,int month, int year){

    if(year > 9999 || year < 0){
      throw new IllegalArgumentException("The year must be between 0 and 9999");
    }
    if(month > 12 || month < 1){
      throw new IllegalArgumentException("The month must be between 1 and 12");
    }
    int maxDay;
    switch (month) {
      case 2:
        boolean leap = (year%4==0 && year%100 != 0)||(year%400==0);
        maxDay = leap?29:28;
        break;
      case 1,3,5,7,8,10,12:
        maxDay = 31;
        break;
      default:
        maxDay = 30;
      }

      if(day > maxDay || day < 1){
        throw new IllegalArgumentException("Enter a valid date for given month");
      }
    dd = day;
    mm = month;
    yyyy = year;
  }
  void displayDate(){
    System.out.printf("%02d/%02d/%04d",dd,mm,yyyy);
  }
}

public class DateViewer{
  public static void main(String[] args) {
    try {
      Date date = new Date(4,3,746);
      date.displayDate();
    } catch (Exception e) {
      System.out.println(e);
    }
  }
}

Create a class Vector3D with data members x, y, and z. Use a constructor to initialize vector components. Write a method to calculate the magnitude of the vector. Create two vector objects and display their magnitudes.


class Vector3D{
  int x,y,z;
  Vector3D(int a,int b,int c){
    x = a;
    y = b;
    z = c;
  }
  void magnitude(){
    double result;
    result = Math.sqrt(x*x + y*y + z*z);
    System.out.printf("The magnitude is %.2f\n",result);
  }
}

public class Vector {
  public static void main(String[] args) {
    Vector3D v1 = new Vector3D(3, 4, 5);
    Vector3D v2 = new Vector3D(6, 7, 3);
    v1.magnitude();
    v2.magnitude();
  }
}

Create a class MyString that stores a string.Use a constructor to initialize the string.Write methods to find the length of the string and compare it with another string object.Display the results.


class MyString{
  String text;
  MyString(String input){
    text = input;
  }
  void size(){
    System.out.println("The length of the string is " + text.length());
  }
  void compare(MyString other){
   int val = text.compareTo(other.text);
   if(val > 0){
    System.out.println(text + " is greater than " + other.text);
   }
   else if(val < 0){
    System.out.println(text + " is lesser than " + other.text);
   }
   else{
    System.out.println("Both are equal strings");
   }
 }
}

public class Text {
  public static void main(String[] args) {
    MyString name1 = new MyString("Suresh");
    name1.size();
    MyString name2 = new MyString("Harshit");
    name2.size();
    name1.compare(name2);
  }
}

Create a class BankAccount with data members accountNumber, accountHolderName, and balance. Initialize the data using a constructor. Display account details. Create multiple objects to represent different customers.


class BankAccount{
 String accountNumber,accountHolderName;
 double balance;

 BankAccount(String no,String name,double bal){
  accountHolderName = name;
  accountNumber = no;
  balance = bal;
 }

 void details(){
  System.out.println("Account Number = " + accountNumber);
  System.out.println("Account Holder = " + accountHolderName);
  System.out.println("Current Balance = " + balance);
 }
}

public class Banking {
  public static void main(String[] args) {
    BankAccount one = new BankAccount("BN4521", "Rohan", 5000);
    BankAccount two = new BankAccount("BN4411", "Ambani", 786000);
    BankAccount three = new BankAccount("BN8221", "Mamta", 7410200);
    BankAccount four = new BankAccount("BN3871", "Shivam", 3000);

    one.details();
    two.details();
    three.details();
    four.details();
  }
}

Create a class Student with data members name, roll, and marks of 3 subjects. Use a constructor to initialize values. Write methods to calculate total and average marks. Display student details with result.


class Student{
  String name;
  int roll;
  int phy,chem,math;

  Student(String text,int no,int p,int c,int m){
    name = text;
    roll = no;
    phy = p;
    chem = c;
    math = m;
  }
  int total(){
    return phy+chem+math;
  }
  double average(){
    return (phy+chem+math)/3;
  }
  void details(){
    System.out.println("--------------------------------------");
    System.out.println("Name = " + name);
    System.out.println("Roll = " + roll);
    System.out.println("--------------------------------------");
    System.out.println("Physics | Chemistry | Maths");
    System.out.printf("%8d|%11d|%5d\n",phy,chem,math);
    System.out.println("--------------------------------------");
    System.out.println("Total Marks = " + total());
    System.out.println("Total Average = " + average());
  }
}

public class StudentMain {
  public static void main(String[] args) {
    Student s1 = new Student("Arham",12,74,71,83);
    s1.details();
  }
}

Create a class Rectangle with data members length and breadth. Initialize values using constructor overloading (default and parameterized). Write a method to calculate area and perimeter. Create objects using both constructors.


class Rectangle{
  double length, breadth;
  Rectangle(){
    length = 1;
    breadth = 1;
  }
  Rectangle(double l,double b){
    length = l;
    breadth = b;
  }
  double area(){
    return length*breadth;
  }
  double perimeter(){
    return 2*(length+breadth);
  }
}

public class Rect {
  public static void main(String[] args) {
    Rectangle r1 = new Rectangle();
    Rectangle r2 = new Rectangle(4.6,3.9);
    System.out.println(r1.area() + "sq.ft and " + r1.perimeter()+ "ft");
    System.out.println(r2.area() + "sq.ft and " + r2.perimeter()+ "ft");

  }
}

Create a class Employee with data members empId, name, and basicSalary. Initialize the details using constructor. Write a method to calculate gross salary (add HRA and DA). Display employee salary details.


class Employee{
  String empId,name;
  int basicSalary;

  Employee(String id,String text,int sal){
    empId = id;
    name = text;
    basicSalary = sal;
  }

  int grossSalary(int hra, int da){
    return hra+da;
  }
  void salaryDetails(int hra, int da){
    System.out.println("Basic Salary = " + basicSalary);
    System.out.println("HRA = " + hra);
    System.out.println("DA = " + da);
    System.out.println("Gross Salary = " + grossSalary(hra, da));
  }
}

public class Emp {
  public static void main(String[] args) {
    Employee e1 = new Employee("ETA4175", "Jeffery", 140000);
    e1.salaryDetails(120000, 45000);
  }
}

Create a class Time with data members hours, minutes, and seconds. Use a constructor to initialize time. Write a method to display time in proper format. Create two objects and display both times.


class Time{
  int hours,minutes,seconds;
  Time(){
    hours = 0;
    minutes = 0;
    seconds = 0;
  }
  Time(int h,int m,int s){
    if((h>-1 && h<24) && (m>-1 && m<60) && (s>-1 && s<60)){
    hours = h;
    minutes = m;
    seconds = s;
    }
    else{
      System.out.println("You have entered an invalid Time");
    }
  }
  void displayTime(){
    System.out.printf("%02d:%02d:%02d\n",hours,minutes,seconds);
  }
}
public class Timeclass {
  public static void main(String[] args) {
    Time time1 = new Time();
    Time time2 = new Time(23,13,58);
    time1.displayTime();
    time2.displayTime();
  }
}

Create a class Book with data members title, author, and price. Initialize using constructor. Write a method to display book information. Create multiple book objects and display details.



class Book{
  String title, author;
  int price;
  Book(String t, String a,int p){
    title = t;
    author = a;
    price = p;
  }
  void bookInfo(){
    System.out.println("Title of the Book : " + title);
    System.out.println("Author of the Book : " + author);
    System.out.println("Price of the Book : " + price);
    System.out.println();
  }
}

public class Books {
  public static void main(String[] args) {
    Book book1 = new Book("Ganit Prakash","Sanjay Palli",200);
    Book book2 = new Book("Bliss","Sumitra Banerjee",30);
    Book book3 = new Book("Bornoparichay","Vidyasagar",50);

    book1.bookInfo();
    book2.bookInfo();
    book3.bookInfo();
  }
}

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Week 2 of OOP in JAVA

Create a class Complex with data members real and imaginary. Use a parameterized constructor to initialize the values. Create a method to add two complex numbers and display the result in the form a + bi. Create objects in the main() method and demonstrate addition.

Create a class Date with data members day, month, and year. Use a constructor to initialize the date. Write a method to display the date in dd/mm/yyyy format. Validate whether the date entered is valid or not.

Create a class Vector3D with data members x, y, and z. Use a constructor to initialize vector components. Write a method to calculate the magnitude of the vector. Create two vector objects and display their magnitudes.

Create a class MyString that stores a string.Use a constructor to initialize the string.Write methods to find the length of the string and compare it with another string object.Display the results.

Create a class BankAccount with data members accountNumber, accountHolderName, and balance. Initialize the data using a constructor. Display account details. Create multiple objects to represent different customers.

Create a class Student with data members name, roll, and marks of 3 subjects. Use a constructor to initialize values. Write methods to calculate total and average marks. Display student details with result.

Create a class Rectangle with data members length and breadth. Initialize values using constructor overloading (default and parameterized). Write a method to calculate area and perimeter. Create objects using both constructors.

Create a class Employee with data members empId, name, and basicSalary. Initialize the details using constructor. Write a method to calculate gross salary (add HRA and DA). Display employee salary details.

Create a class Time with data members hours, minutes, and seconds. Use a constructor to initialize time. Write a method to display time in proper format. Create two objects and display both times.

Create a class Book with data members title, author, and price. Initialize using constructor. Write a method to display book information. Create multiple book objects and display details.

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