🔹 Constructor in Java 

When you create an object in Java, you often want it to start with some initial values. That’s where a constructor comes in!
Think of it like the entry gate of a house – whenever you enter (create an object), it decides how things will look inside.

✨ What is a Constructor?

A constructor in Java is a special method that:

• Has the same name as the class.

• Does not have a return type (not even void).

• Is automatically called when an object is created.

👉 In short: It initializes objects!

🛠 Types of Constructors in Java

1️⃣ Default Constructor

• Provided by Java automatically if you don’t create any constructor.

• Initializes object with default values (0, null, false, etc.).

class Student {
    String name;
    int age;
    
    // Default constructor
    Student() {
        name = "Unknown";
        age = 0;
    }
}

public class Main {
    public static void main(String[] args) {
        Student s1 = new Student(); // Constructor called automatically
        System.out.println(s1.name + " - " + s1.age);
    }
}

2️⃣ Parameterized Constructor

• Used when you want to initialize objects with specific values.

class Student {
    String name;
    int age;
    
    // Parameterized constructor
    Student(String n, int a) {
        name = n;
        age = a;
    }
}

public class Main {
    public static void main(String[] args) {
        Student s1 = new Student("Amit", 21);
        Student s2 = new Student("Riya", 22);
        System.out.println(s1.name + " - " + s1.age);
        System.out.println(s2.name + " - " + s2.age);
    }
}

3️⃣ Constructor Overloading

• You can define multiple constructors in a class with different parameters.

• Java will decide which one to call based on arguments.

class Student {
    String name;
    int age;

    // Default constructor
    Student() {
        name = "Not Assigned";
        age = 0;
    }

    // Parameterized constructor
    Student(String n, int a) {
        name = n;
        age = a;
    }
}

public class Main {
    public static void main(String[] args) {
        Student s1 = new Student(); // Calls default
        Student s2 = new Student("Rahul", 20); // Calls parameterized
        System.out.println(s1.name + " - " + s1.age);
        System.out.println(s2.name + " - " + s2.age);
    }
}

🚀 Why are Constructors Important?

✅ Save time by initializing objects automatically.
✅ Increase code readability.
✅ Essential for object-oriented programming (OOP).

📌 Quick Recap

• Constructors initialize objects.

• Same name as the class, no return type.

• Types: Default, Parameterized, Overloaded.

💡 Pro Tip for Students: Constructors are one of the most asked concepts in Java exams & interviews. Practice writing small classes with multiple constructors to master them!