Constructor Overloading in Java

Constructor overloading is a technique where a class has more than one constructor, each with a different parameter list. It allows objects to be created in different ways depending on the arguments provided.

Example

class Student {
    String name;
    int age;

    Student() {
        this.name = "Unknown";
        this.age = 0;
    }

    Student(String name) {
        this.name = name;
        this.age = 0;
    }

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

Student s1 = new Student();
Student s2 = new Student("Karan");
Student s3 = new Student("Meera", 23);

Rules for Constructor Overloading

• Each constructor must differ in the number, type, or order of parameters
• Constructors share the class name, so overloading relies entirely on parameter lists
• One constructor can call another using this() to avoid repeating initialization logic

Why Use Constructor Overloading?

• Gives users of the class flexibility to create objects with different amounts of initial information
• Supports default values when certain fields aren't provided
• Improves code usability without duplicating the entire class logic