super Keyword in Java

The super keyword in Java is used to refer to the parent class of a subclass.

Uses of super keyword in Java

It can be used to:

• Call a superclass constructor
• Access a superclass field
• Call a superclass method

Call superclass constructor

When a subclass is created, its constructor must call the constructor of its parent class. This is done using the super() keyword, which calls the constructor of the parent class.

For example:

class Animal {
  public Animal() {
    System.out.println("Animal constructor");
  }
}

class Dog extends Animal {
  public Dog() {
    super(); // This calls the Animal constructor
    System.out.println("Dog constructor");
  }
}

Access superclass field or variable

If a subclass has a field with the same name as a field in its parent class, the super keyword can be used to access the field in the parent class.

For example:

class Animal {
  protected String color = "white";
}

class Dog extends Animal {
  public String color = "black";

  public void printColor() {
    System.out.println(this.color); // Prints "black" from child class
    System.out.println(super.color); // Prints "white" from parent class
  }
}

Call superclass method

If a subclass overrides a method in its parent class, the super keyword can be used to call the method in the parent class.

For example:

class Animal {
  public void makeSound() {
    System.out.println("Animal sound");
  }
}

class Dog extends Animal {
  @Override
  public void makeSound() {
    System.out.println("Woof!");
  }

  public void callSuperMakeSound() {
    super.makeSound(); // This calls the Animal.makeSound() method
  }
}

The super keyword can be a useful tool for accessing and calling methods and fields in the parent class. It is important to use it correctly to avoid errors.

Things to keep in mind about the super keyword

• The super keyword must be the first statement in a constructor.
• The super keyword cannot be used in a static context.
• The super keyword can be used to access the superclass constructor, even if the subclass has its own constructors.

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