Breakdown of Your Code

Let’s analyze the structure of the parameterized constructor you provided:

class Student {
    String name;
    int age;

    // Parameterized Constructor
    Student(String n, int a) { 
        name = n; // "n" is assigned to the object's name
        age = a;  // "a" is assigned to the object's age
    }
}

• String n, int a: These are the parameters. They act as “placeholders” for the data you will send.

• Assignment: The code inside the {} takes the values from the parameters and stores them in the class variables (name and age).

2. How to Use It (The Main Method)

When using a parameterized constructor, you provide the values inside the parentheses of the new statement.

public class Main {
    public static void main(String[] args) {
        // One-line creation and initialization
        Student s1 = new Student("Ali", 15);
        Student s2 = new Student("Sara", 18);

        System.out.println(s1.name + " is " + s1.age); // Output: Ali is 15
        System.out.println(s2.name + " is " + s2.age); // Output: Sara is 18
    }
}

3. Advantages for Students

Using this type of constructor is standard practice in Java for several reasons:

1. Efficiency: You don’t need to write s1.name = "Ali"; and s1.age = 15; on separate lines. It saves time and space.

2. Mandatory Data: You can force a rule that “No student can be created without a name.” If someone tries to write new Student();, the code will not compile, preventing “empty” data errors.

3. Multiple Objects: It makes it very easy to initialize hundreds of objects in a loop or an array.

4. Important Rule: The “Disappearing” Default Constructor

This is a very common Multiple Choice Question (MCQ) in university exams:

Rule: Once you define any parameterized constructor in your class, Java stops providing the automatic Default Constructor.

If you want to be able to create a student both ways—with data and without data—you must manually write both constructors in your class. This is called Constructor Overloading.

5. Summary Table

Practice Scenario:

Imagine you are building a Library System. You have a class Book.

• Attributes: title, author.

• Task: Create a parameterized constructor so you can create a book like this:

  Book b1 = new Book(“Java Basics”, “James Gosling”)