Constructor - super

A constructor is a special method used to initialize objects.
It runs automatically when an object is created.

class Car {
    Car() {
        System.out.println("Car created");
    }
}

What is super()?

Super() is a call to the parent class constructor. It must be the first statement in a child constructor.

class Vehicle {
    Vehicle() {
        System.out.println("Vehicle constructor");
    }
}
 
class Car extends Vehicle {
    Car() {
        super(); // calls Vehicle()
        System.out.println("Car constructor");
    }
}
 
Car car = new Car(); // Vehicle Constructor → Car Constructor

Key Points

• Every constructor implicitly calls super() if no other constructor call is specified.
• You can use super(args) to call specific parent constructor.
• If parent has no default (no-arg) constructor, you must explicitly call a matching one.
• super() is only used inside a constructor - not in methods.

Constructor Overloading + super()

class Vehicle {
    Vehicle(String name) {
        System.out.println("Vehicle: " + name);
    }
}
 
class Bike extends Vehicle {
    Bike() {
        super("Bike"); // Calls parent constructor with arg
        System.out.println("Bike ready");
    }
}

Comparison

super() vs this()

Keyword	Calls…	Used For
this()	Another constructor (same class)	Constructor chaining within class
super()	Parent class constructor	Inheritance-base constructor chaining

Tip

Be ready to explain:

• why super() must come first,
• what happens if the parent doesn’t have a default constructor,
• how super() helps with constructor chaining.

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Parent: _OOP