DEV Community: PRIYA K

PinCode,Mobile Number,Email Validation in Python

PRIYA K — Mon, 27 Apr 2026 04:12:21 +0000

1. Check whether a given number is a valid 6-digit pincode or not.

def pincode(pc):
    if pc//100000!=0 and pc//100000<=9:
        print("Yes")
    else:
        print("No")
pincode(int(input("Enter a pincode :")))

Output

2. Check whether a given email ID is a valid Gmail address or not.

def verify_Gmail(Gmail):
    if Gmail[-10:]=="@gmail.com":
        i=0
        gmailcopy=Gmail[0:len(Gmail)-10]
        while i<len(gmailcopy):
            current=gmailcopy[i]
            i+=1
            if current>="a" and current<="z":
                continue;
            elif current>="A" and current<="Z":
                continue;
            elif current>="0" and current<="9":
                continue;
            elif current=="." or current=="_":
                continue;
            else:
                return False
        return True
    else:
        return False

if verify_Gmail(input("Enter Your Gmail :")):
    print("valid")
else:
    print("invalid")

Output

3. Check whether a given input is a valid Indian mobile number or not.

def verify(mobnum):
    index=0
    while index<len(mobnum):
        if mobnum[index]>="0" and mobnum[index]<="9":
            index+=1
            continue;
        else:
            return False
    return True

def mobile(n):
    i=0
    while i<len(n):
        if(n[i]>="0" and n[i]<="9") or (n[i]=="+") or (n[i]==" "):
            i+=1
        else:
            return "characters and special charactors not allowed"

    if len(n)==10:
        if n[0]>="6" and n[0]<="9" and verify(n):
            return "valid";
        else:
            return "incorrect"

    if len(n)==13:
        if n[0:3]=="+91":
            if n[3]>="6" and n[3]<="9" and verify(n[3:]):
                return "valid"
            else:
                return "incorrect"
        return "First three number should like +91"

    if len(n)==14:
        if n[0:4]=="+91 ":
            if n[4]>="6" and n[4]<="9" and verify(n[4:]):
                return "valid"
            else:
                return "incorrect"
        return "First four number should like +91 "
    return "Please Enter Your valid Mobile Number"      
print(mobile(input("Enter Your Mobile  Number : ")));

Output

String Program

PRIYA K — Mon, 27 Apr 2026 04:04:36 +0000

1. Given string to uppercase

text=input("Enter some words :")
i=0
upper=""
while i<len(text):
    ch=text[i]
    if ch>="a" and ch<="z":
        upper=upper+chr(ord(ch) - 32)
    else:
        upper=upper+ch
    i+=1
print(upper)

Output

2. First letter to Uppercase

text=input("Enter some words :")
i=0
upper=""
while i<len(text):
    ch=text[i]
    if (ch>="a" and ch<="z") and (text[i-1]==" " or i==0):
        upper=upper+chr(ord(ch) - 32)
    else:
        upper=upper+ch
    i+=1
print(upper)

Output

3. Letter Count

text=input("Enter some words :")
i=0
count=0
while i<len(text):
    ch=text[i]
    if (ch>="a" and ch<="z") or (ch>="A" and ch<="Z"):
        count+=1
    i+=1
print(count)

Output

4. Word count

text=input("Enter some words :")
i=0
count=1
while i<len(text):
    if text[i]!=" " and text[i-1]==" ":
        count+=1
    i+=1
print(count)

Output

5. Password Validator

text=input("Enter password : ")

i=0
upper=False
lower=False
number=False
special=False
others=True

while i<len(text):
    ch=text[i]

    if ch>="A" and ch<="Z":
        upper=True

    elif ch>="a" and ch<="z":
        lower=True

    elif ch>="0" and ch<="9":
        number=True

    elif ch=="!" or ch=="@" or ch=="#" or ch=="$" or ch=="&":
        special=True

    else:
        others=False

    i+=1

if len(text)>=8 and upper and lower and number and special and others:
    print("Valid Password")
else:
    print("Invalid Password")

Output

6. Password Generator

import random

upper="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
lower="abcdefghijklmnopqrstuvwxyz"
numbers="0123456789"
special="!@#$&"

all_chars=upper+lower+numbers+special

password=""

password=password+random.choice(upper)
password=password+random.choice(lower)
password=password+random.choice(numbers)
password=password+random.choice(special)

i=4

while i<8:
    password=password+random.choice(all_chars)
    i+=1

print("Generated Password :",password)

Output

Validate Indian Pincode Using Python

PRIYA K — Mon, 27 Apr 2026 03:40:46 +0000

** Validate Indian Pincode Using Python(Region, Sub-Region and District Finder)**

regions = {
    1: "Delhi",
    2: "Uttar Pradesh & Uttarakhand",
    3: "Rajasthan & Gujarat",
    4: "Maharashtra",
    5: "Andhra Pradesh & Telangana",
    6: "Tamil Nadu & Kerala",
    7: "West Bengal & North East",
    8: "Bihar & Jharkhand",
    9: "Army Postal Service"
}

sub_regions = {
    11: "Delhi Region",
    40: "Mumbai Region",
    60: "Chennai Region",
    70: "Kolkata Region"
}

districts = {
    110: "Delhi",       111: "Delhi (North)",      112: "Delhi (South)",
    400: "Mumbai",      401: "Mumbai (Suburban)",   402: "Mumbai (West)",
    600: "Chennai",     601: "Tiruvallur",          602: "Kanchipuram",
    700: "Kolkata",     701: "Kolkata (North)",     702: "Kolkata (South)"
}

def get_pincode_details(pincode):
    if not pincode.isdigit() or len(pincode) != 6:
        print("Invalid pincode. Enter exactly 6 digits.")
        return

    num         = int(pincode)
    first_digit = num // 100000
    first_two   = num // 10000
    first_three = num // 1000

    print("Region:     ", regions.get(first_digit,   "Unknown"))
    print("Sub-region: ", sub_regions.get(first_two, "Unknown"))
    print("District:   ", districts.get(first_three, "Unknown"))


pincode = input("Enter 6-digit Pincode: ").strip()
get_pincode_details(pincode)

Output

String program

PRIYA K — Mon, 27 Apr 2026 02:27:45 +0000

1. Remove extra space

name = "priya working as software developer"
result = ""
i = 0
while i < len(name):
    if name[i] != " ":
        result = result + name[i]
    else:
        if name[i-1] != " ":
            result = result + name[i]
    i += 1

print(result)

Output

2.Front space remove

name = "priya working as software developer"
i = 0
result = ""

while i < len(name):
    if name[i] != " ":
        break   
    i += 1

while i < len(name):
    result += name[i]
    i += 1

print(result)

Output

3. Remove last space

name = "priya working as software developer   "
result = ""
i = len(name)-1

while i >= 0:

    if name[i] == " ":
        i -= 1
        continue

    else:
        j = 0

        while j <= i:
            result += name[j]
            j += 1

        break

print(result)

Output

4. Reverse a word

name = input("Enter word:")
result = ""

i = len(name)-1

while i >= 0:
    result = result + name[i]
    i -= 1

print(result)

Output

How to Create a Supermarket Billing System in Java Using OOPS Concepts

PRIYA K — Tue, 21 Apr 2026 13:46:34 +0000

public class Supermarket {

    String name;
    double mrp;
    boolean discountApplied;
    double discountPercent;

    // Default Constructor
    Supermarket() {
        name = "Unknown";
        mrp = 0.0;
        discountApplied = false;
        discountPercent = 0;
    }

    // Constructor Overloading (without discount)
    Supermarket(String name, double mrp) {
        this.name = name;
        this.mrp = mrp;
        this.discountApplied = false;
        this.discountPercent = 0;
    }

    // Constructor Overloading (with discount)
    Supermarket(String name, double mrp, boolean discountApplied, double discountPercent) {
        this.name = name;
        this.mrp = mrp;
        this.discountApplied = discountApplied;
        this.discountPercent = discountPercent;
    }

    // Method: Billing (no parameters)
    void Billing() {

        double finalPrice = mrp;

        System.out.println("Item Name: " + name);
        System.out.println("MRP Price: ₹" + mrp);
        System.out.println("Discount Applied: " + discountApplied);

        if (discountApplied) {
            double discountAmount = (mrp * discountPercent) / 100;
            finalPrice = mrp - discountAmount;
            System.out.println("Discount Percentage: " + discountPercent + "%");
        } else {
            System.out.println("Discount Percentage: 0%");
        }

        System.out.println("Final Price: ₹" + finalPrice);
        System.out.println("-----------------------------");
    }

    // Method Overloading (optional usage)
    void Billing(boolean discountApplied, double discountPercent) {
        this.discountApplied = discountApplied;
        this.discountPercent = discountPercent;
        Billing(); // reuse main method
    }

    // Main Method
    public static void main(String[] args) {

        // Object without discount
        Supermarket item1 = new Supermarket("Rice", 100);
        item1.Billing();

        // Object with discount
        Supermarket item2 = new Supermarket("Oil", 200, true, 10);
        item2.Billing();

        // Another example
        Supermarket item3 = new Supermarket("Sugar", 50, false, 0);
        item3.Billing();
    }
}

Output

Constructor in Java

PRIYA K — Sat, 18 Apr 2026 04:33:27 +0000

A special method used to initialise objects.
Constructor is a block of code similar to method
Constructor is called when an object of a class is created

All Classes have constructors by 'default'
Java (JDK) creates a Class Constructor ,you need not to create a Class constructor
Accept parameters to initialise Object properties
It is used to set default or user-defined values for the object's attributes
Initialise objects at the time of object creation.

Constructor Syntax

class ClassName {
    // Constructor
    ClassName() {
        // Initialization code
    }

    // Parameterized Constructor
    ClassName(dataType parameter1, dataType parameter2) {
        // Initialization code using parameters
    }

    // Copy Constructor
    ClassName(ClassName obj) {
        // Initialization code to copy attributes
    }
}

Example

class Bike{
    Bike(){
        System.out.println("Bike is created");
    }
    public static void main(String[]args){
        Bike b = new Bike();

    }

}

Output

Rules For Creating Constructor
1.Name Rule
Constructor name must match the Class name
2.Return Type Rule
It cannot have a return type (like void) or explicit return type
if you add a return type,it will become a method not a return type
3.Execution Rule
A constructor is called as per the object creation(New)
4.Default Constructor Rule
No constructor is defined, Java provides a default no-arg constructor.
you can define any constructor, the default is not automatically provided.
5.Access Modifiers Rule
A constructor have modifiers like Private,Public,Protected or default
Private Constructore have used in singleton Design Pattern
to be discussed...
6.Restrictions Rule
A constructor cannot be

static(Belong to Class,not Objects) because Constructor is called using Objects.static is called by class
final(Not Inherited)
abstract(must have a body)
and synchronised to be discussed...

7.Inheritance Rule
Constructor not inherited by SubClass
Call a Parent Constructor using Super()

8.this() and super() Rule
A constructor can call another constructor in the same class using this().
A constructor can call a parent’s constructor using super().
In Java ≤ 24 → must be the first statement.
In Java 25 → can appear anywhere in the constructor.

Types Of Constructor

Default Constructor
Parameterised Constructor
No-argument Constructor

Default Constructor (Implicit)
A constructor doesnot have any parameter
Doesnot defined any constructor
A constructor that is automatically provided by Java if no constructor is written in the class.
It initializes object with default values (0, null, false).

Example
It is called when the object of the class is created

class Bike {
    int id;
    String name;

    void display() {
        System.out.println(id + " " + name);
    }

    public static void main(String[] args) {
        Bike b = new Bike();   // calls default constructor
        b.display();
    }
}

Output

Purpose Of Default Constructor
Provide Default values to the object like 0,null.depending on their data type.

No-Argument Constructor(User-defined)
user-defined empty constructor
A constructor that is manually written by the programmer with no parameters.
It is used to initialize objects with custom default values.

class Bike {
    int id;
    String name;

    // No-argument constructor
    Bike() {
        id = 101;
        name = "Duke";
    }

    void display() {
        System.out.println(id + " " + name);
    }

    public static void main(String[] args) {
        Bike b = new Bike();
        b.display();
    }
}

Output

Parameterised Constructor(Explicit)
A constructor have a any number of parameter
Used to provide different value for objects
Accepts arguments to initialize an object with specific values.
It allows passing values while creating the object.

class Bike {
    int id;
    String name;

    // Constructor only initializes values
    Bike(int id, String name) {
        this.id = id;
        this.name = name;
    }

    // Method to display bike details
    void display() {
        System.out.println(id + " " + name);
    }

    public static void main(String[] args) {
        Bike b = new Bike(111, "Duke");
        Bike p = new Bike(122, "Splender");

        b.display();
        p.display();
    }
}

Output

Constructor OverLoading
Allows to create multiple constructors in the same class with different parameter and different data type
It can be overloaded like Java Methods
You can define all type of Constructors like no-argument and parameterised constructor.

Example

class Bike {
    int id;
    String name;

    // 1. Constructor with no parameters
    Bike() {
        id = 0;
        name = "Null";
    }

    // 2. Constructor with one parameter
    Bike(int id) {
        this.id = id;
        this.name = "Default Bike";
    }

    // 3. Constructor with two parameters
    Bike(int id, String name) {
        this.id = id;
        this.name = name;
    }

    void display() {
        System.out.println(id + " " + name);
    }

    public static void main(String[] args) {
        Bike b1 = new Bike();              // calls 1st constructor
        Bike b2 = new Bike(111);           // calls 2nd constructor
        Bike b3 = new Bike(122, "Duke");   // calls 3rd constructor

        b1.display();
        b2.display();
        b3.display();
    }
}

Output

What is this() in java 25 Upadte
It is used to call another Constructor with the same class(Constructor Chaining)
The restriction this() and super() used as first statement in constructor is removed.
Place them anywhere inside a constructor
this() and super()=>they enable clean and flexible initialization.

Copy Constructor
A constructor that creates a new object by copying values from an existing object of the same class.
It is used to duplicate objects.

class Bike {
    int id;
    String name;

    Bike(int id, String name) {
        this.id = id;
        this.name = name;
    }

    // Copy constructor
    Bike(Bike b) {
        this.id = b.id;
        this.name = b.name;
    }

    void display() {
        System.out.println(id + " " + name);
    }

    public static void main(String[] args) {
        Bike b1 = new Bike(111, "Duke");

        Bike b2 = new Bike(b1);  // copy constructor

        b1.display();
        b2.display();
    }
}

Output

Do You Know?
1.this Keyword (Avoid confusion)
Used when class variable and parameter have same name
this refers to current class constructor
this refers to current object
this() calls another constructor in the same class .This technique is called Constructor Chaining

Example:

class Bike {
    int id;
    String name;

    Bike(int id, String name) {
        this.id = id;      // class variable = parameter
        this.name = name;
    }
}

Explanation
this.id → object’s variable
id → constructor parameter

Without this, Java gets confused

2.Constructor Chaining (this())

One constructor calling another constructor
Simple idea:
“Reuse constructor instead of writing same code again”

Example:

class Bike {
    int id;
    String name;

    Bike() {
        this(0, "Unknown");  // calls another constructor
    }

    Bike(int id, String name) {
        this.id = id;
        this.name = name;
    }
}

Bike() → calls Bike(int, String)
Saves duplicate code

3.Immutable Object (Fixed data)

Once object is created, you cannot change its values
Means
“Lock the object after creation "

Example:

class Student {
    private final String name;
    private final int age;

    Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }
}

final → cannot change value
No setter methods → data is fixed

4. Exception Handling in Constructor
Handle errors while creating object
stop invalid object creation

Means
“If object is wrong, stop it immediately”

Example:

class Student {
    int age;
    Student(int age) {
        if (age < 0) {
            throw new Illegal ArgumentException("Age cannot be negative");
        }
        this.age = age;
    }
}

If invalid data comes → constructor blocks it
Object is created only if data is correct

Installation vs Deployment

PRIYA K — Mon, 13 Apr 2026 02:43:21 +0000

What is Installation?

Installation means setting up software on a system so that it can run.
It is the process where required files, dependencies, and configurations are placed on a device (like your laptop or server).

Example:
When you install:
Node.js
Python
React app using npm install
You are preparing your environment to run the application.

Points to Remember
Happens on a local system or server
Focus is on setup
Includes dependencies, libraries, and configurations
Done by developers or users

What is Deployment?
Deployment means making your application available for users to access.
It is the process of moving your application from your local system to a live server or production environment.

Example:
Uploading your React app to Netlify
Hosting a website on AWS
Publishing an app so users can access it online

Points to Remember
Happens on a production server
Focus is on making the app live
Includes hosting, domain, and server configuration
Done by developers or DevOps teams

Simple Flow
Install → Setup environment
Develop → Build your application
Deploy → Make it live for users

Real-Life Analogy
Think of it like cooking:
Installation = Buying ingredients & setting up kitchen
Deployment = Serving the food to customers

Installation and deployment are both important steps in software development:
Without installation, your app won’t run
Without deployment, users can’t access it
Understanding this difference helps you work better in development and production environments.

Selenium Basics

PRIYA K — Mon, 13 Apr 2026 02:42:25 +0000

Testing web applications manually can be time-consuming and error-prone.

What is Selenium?
Selenium is an open-source tool used for automating web browsers.
It allows developers and testers to write scripts that simulate real user actions like:
Clicking buttons
Entering text
Navigating pages

Why Selenium is Used?
Selenium is mainly used for testing web applications automatically.

Key Reasons:
Reduces manual testing effort
Saves time
Improves accuracy
Supports multiple browsers

Components of Selenium
Selenium is not just one tool—it has multiple components:

Selenium WebDriver Most important part Directly interacts with browser Supports languages like Java, Python, JavaScript
Selenium IDE Browser extension (Chrome/Firefox) Record and playback tool Beginner-friendly
Selenium Grid Used for running tests on multiple machines Supports parallel testing

How Selenium Works?
Selenium works by controlling the browser using code.

Write test script
WebDriver sends commands
Browser executes actions
Result is returned

Supported Browsers
Selenium works with:
Chrome
Firefox
Edge
Safari

Advantages of Selenium
Open-source (free)
Supports multiple languages
Cross-browser testing
Large community support

Limitations of Selenium
Only for web applications (not desktop apps)
Requires programming knowledge
No built-in reporting

Real-Time Use Case
Imagine you built a login page. Instead of testing it manually every time:
Selenium can:
Enter username/password
Click login
Verify success message
Automatically

Simple Analogy
Think of Selenium like a robot user
It behaves exactly like a human using a browser—but faster and without mistakes.

Selenium is a powerful tool for automating web testing. Learning its basics is a great step for anyone interested in software testing, QA, or automation engineering.

Self-Introduction

PRIYA K — Thu, 09 Apr 2026 21:53:56 +0000

This is Priya, and I’m from Chennai.

I have completed my Bachelor of Technology in Artificial Intelligence and Data Science from Rajalakshmi Institute of Technology .

Coming to my technical skills, I have a strong foundation in HTML, CSS, and JavaScript, and I also have practical knowledge of React.js for building responsive and user-friendly web applications. I am also familiar with tools like Git, GitLab, and VS Code.

I completed an internship as a Data Science Intern at Unified Mentor, where I worked on data cleaning, exploratory data analysis, and data visualization using Python. I also developed recommendation systems and machine learning models for classification tasks.

For my projects, I developed an Interactive Quiz Web Application using React.js. In this project, I used React Hooks like UseState, UseEffect, and UseContext, and implemented React Router for smooth navigation. This helped me strengthen my Front-end development skills.

I also worked on a major project titled Skin Disease Classification using deep learning. I used CNN models like Alex Net and U-Net and achieved around 91.95% accuracy. I also developed a Django-based web application for real-time disease detection and treatment suggestions.

Additionally, I presented this project in a conference, which helped me improve my communication and presentation skills.

I am a quick learner, passionate about web development and AI, and always interested in learning new technologies. I am looking for an opportunity where I can improve my skills, gain real-time experience, and contribute to the organization.

Method in java

PRIYA K — Thu, 09 Apr 2026 05:11:04 +0000

Void Method(with return type)
example

public class Display{
    public static void main(String[]args){
        Display casio = new Display();
        casio.add();
    }
    public void add(){
        return;
    }
}

Flow of execution
main()
│
│ create object
▼
Display casio = new Display()
│
│ method call
▼
casio.add()
│
▼
add() method executes
│
▼
return;
│
▼
control returns to main()
│
▼
program ends

Marks Calculation

Example

public class Marks{

    public static void main(String[] args){
        int total = sumMarks(100,98,78,95,91);
        int avg = average(total);
        grade(avg);
    }

    public static int sumMarks(int m1,int m2,int m3,int m4,int m5){
        int total = m1 + m2 + m3 + m4 + m5;
        return total;
    }

    public static int average(int total){
        int avg = total/5;
        return avg;
    }

    public static void grade(int avg){
        if(avg>=90){
            System.out.println("A");
         }
        else if(avg>=80){
            System.out.println("B");
         }
        else if(avg>=70){
            System.out.println("C");
         }
        else if(avg>=60){
            System.out.println("D");
         }
        else if(avg>=50){
            System.out.println("E");
         }
        else{
            System.out.println("Fail");
        }
    }
}

Flow of Execution

Program starts in main()
sumMarks() is called
Total marks calculated → 462
average() is called
Average calculated → 92
grade() is called
Condition checked → 92 ≥ 90
Grade printed → A

Constructor in JavaScript

PRIYA K — Thu, 09 Apr 2026 05:10:32 +0000

A constructor function is a special function used to create many objects with the same structure.
Curly braces represent an object.
Create many Objects easily.
Each Key-value pair is called Property
Instead of writing many objects manually, we create a blueprint
name constructor functions with an upper-case first letter.

constructor()
Special method inside a class
Runs automatically when object is created

function Person(name, age) {

Explanation
function Person(name, age)

function → keyword to define a function
Person → constructor name
name, age → parameters

Understanding this
this.name = name;
this=>refers to the current object being created

this.name=>creates a property called name inside the object

= name(assigns the value received from the parameter)

Example :

{
   name : "Priya"
}

this.age = age;
creates an age property
stores the value passed to the constructor

object becomes:

{
name : "Priya",
age : 21
}

Steps:

Creates an empty object { }
Sets this to point to that object
Calls the constructor function
Assigns values (name, age)
Returns the object

Instantiating an object constructor
There are two ways to instantiate object constructor,

const object_name = new Object(); 
const object_name = { };

function Person(first, last, age, eye) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eye;
}

// Create a Person object
const myFather = new Person("John", "Doe", 50, "blue");
const myMother = new Person("Saraswathi","g",42,"black")
console.log(myFather.age)

Explanation
In constructor function,'this' has no value
this value = new object value

Property Default Value

function Person(first, last, age, eye) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eye;
  this.nationality = "English";
}

// Create 2 Person objects
const myFather = new Person("John", "Doe", 50, "blue");
const myMother = new Person("Sally", "Rally", 48, "green");
console.log(myMother.nationality)

Adding Property to an Object

function Person(first, last, age, eye) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eye;
}

// Create 2 Person objects
const myFather = new Person("John", "Doe", 50, "blue");
const myMother = new Person("Sally", "Rally", 48, "green");

// Add nationality to first object
myFather.nationality = "English";
console.log(myFather.nationality)

Adding Property to Constructor

function Person(first, last, age, eye) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eye;
}

// Create 2 Person Objects
const myFather = new Person("John", "Doe", 50, "blue");
const myMother = new Person("Sally", "Rally", 48, "green");

// Will Not Work
Person.nationality = "English";
console.log(Person.nationality)

Add a new property add it to constructor function prototype

function Person(first, last, age, eye) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eye;
}

// Create 2 Person Objects
const myFather = new Person("John", "Doe", 50, "blue");
const myMother = new Person("Sally", "Rally", 48, "green");

// Add a new Property
Person.prototype.nationality = "English";
console.log(myFather.nationality)

Explanation
Person.nationality =>Property belongs to constructor only.
Person.prototype.nationality => Property shared by all objects.

Constructor Function Methods
can have methods

function Person(first, last, age, eye) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eye;
  this.fullName = function() {
    return this.firstName + " " + this.lastName
  };
}

// Create a Person object
const myFather = new Person("John", "Doe", 50, "blue");
console.log(myFather.fullName())

Adding method to an object

function Person(first, last, age, eye) {
  this.firstName = first;
  this.lastName = last;
  this.age = age;
  this.eyeColor = eye;
}

// Create 2 Person objects
const myFather = new Person("John", "Doe", 50, "blue");
const myMother = new Person("Sally", "Rally", 48, "green");

// Add a Name Method
myMother.changeName = function (name) {
  this.lastName = name;
}

// Change Name
myMother.changeName("Doe");
console.log(myMother.lastName)

Output
Doe

Calling the Method

p1.sayHello();

Output:
My name is Priya and I am 21 years old.

Adding a Method to a Constructor
Adding a new method to a constructor must be done to the constructor function prototype:

function Person(firstName,lastName,age,eyeColor) {
  this.firstName = firstName;
  this.lastName = lastName;
  this.age = age;
  this.eyeColor = eyeColor;
}

// Create a Person Object
const myMother = new Person("Sally","Rally",48,"green");

Person.prototype.changeName = function (name) {
  this.lastName = name;
}

// Change Name
myMother.changeName("Doe");
console.log(myMother.lastName)

Built-in JavaScript Constructors

JavaScript has built-in constructors for all objects:
new Object() // A new Object object
new Array() // A new Array object
new Map() // A new Map object
new Set() // A new Set object
new Date() // A new Date object
new RegExp() // A new RegExp object
new Function() // A new Function object

Example

 "";           // primitive string
0;            // primitive number
false;        // primitive boolean

{};           // object object
[];           // array object
/()/          // regexp object
function(){}; // function

Need to Rememeber

The Math() object is not in the list. Math is a global object. The new keyword cannot be used on Math.
Use object literals {} instead of new Object().
Use array literals [] instead of new Array().
Use pattern literals /()/ instead of new RegExp().
Use function expressions () {} instead of new Function().

** Simple Real-Life Example**

Constructor = factory machine
Person constructor
|
|---- Person1
|---- Person2
|---- Person3
Each object has same structure but different values.

Why Constructors are Useful
Without constructor:

object1
object2
object3

You must write many objects manually.

With constructor:
Person() → blueprint
|
|---- p1
|---- p2
|---- p3
You can easily create many objects.

Constructor Using Class (Modern Way)

class Student {
    constructor(name, age) {
        this.name = name;
        this.age = age;
    }
}

let student = new Student("Priya", 22);
console.log(Student);

Constructor Function (Old Way)
Before ES6, constructors were written like this:

function Student(name, age) { 
    this.name = name; 
    this.age = age; 
} 

let student = new Student("Priya", 22);

This still works, but modern JS prefers class syntax.

Concept Meaning
Object Collection of properties
Constructor Blueprint to create objects
this Refers to current object
new Creates a new object
Method Function inside object

Method OverLoading

PRIYA K — Thu, 09 Apr 2026 05:10:15 +0000

1. What is Method Overloading?
Method Overloading is a feature in Java

where multiple methods have the same method name and same number of parameters,arguments but different parameters , different data type in the same class.
It is the one of the Polymorphism called the Compile-Time Polymorphism
The methods differ by:
Number of parameters
Type of parameters
Order of parameters

Example

public class Sample{
    public static void main(String[]args){
        Sample casio = new Sample();
        casio.add(10,20);
        casio.add(10,20,30);
        casio.add();
    }
    public void add(int no1,int no2){
        System.out.println("2 arguments");
    }
    public void add(){
        System.out.println("0 arguments method");
    }
    public void add(int no1,int no2,int no3){
        System.out.println("3 arguments");
    }
}

Output

2.Rules of Method Overloading

Not Change the Number of Parameters

class SumExample {

    int sum(int a, int b) {
        return a + b;
    }

    int sum(int a, int b, int c) {
        return a + b + c;
    }

    public static void main(String[] args) {
        SumExample obj = new SumExample();

        System.out.println(obj.sum(10, 20));
        System.out.println(obj.sum(10, 20, 30));
    }
}

Output

Not Change the Data Type of Parameters

class PrintExample {

    void print(int a) {
        System.out.println("Integer: " + a);
    }

    void print(String a) {
        System.out.println("String: " + a);
    }

    public static void main(String[] args) {
        PrintExample obj = new PrintExample();

        obj.print(100);
        obj.print("Java");
    }
}

Output

Not Change the Order of Parameters

class ShowExample {

    void show(int a, String b) {
        System.out.println(a + " " + b);
    }

    void show(String b, int a) {
        System.out.println(b + " " + a);
    }

    public static void main(String[] args) {
        ShowExample obj = new ShowExample();

        obj.show(10, "Java");
        obj.show("Hello", 20);
    }
}

Output

Changing only the return type is NOT allowed in Java.
Example

class Calculator {

    int multiply(int a, int b){
        return a * b;
    }

    int multiply(int a, int b, int c){
        return a * b * c;
    }

    double multiply(double a, double b){
        return a * b;
    }

    public static void main(String[] args){

        Calculator obj = new Calculator();

        System.out.println(obj.multiply(5, 4));
        System.out.println(obj.multiply(2, 3, 4));
        System.out.println(obj.multiply(2.5, 4.0));
    }
}

Output

3. Step-by-Step Execution
Program starts from the main() method
Object of the class is created
Method is called using the object
Java compares the arguments with method parameters
The correct overloaded method runs
Output is displayed

4.Advantage Of Method OverLoading
Keep code clean and readable
Use the same method name for similar operations
Avoid creating many method names
Make programs easier to maintain

5. Simple Real-Life Idea
Think of a mobile phone camera:

Same button → Camera
Different modes:
Photo
Video
Portrait

Same name, different behavior depending on input.