Java super Keyword
In Java, the super keyword is used to refer to the parent class of a subclass.
The most common use of the super keyword is to eliminate the confusion between superclasses and subclasses that have methods with the same name.
It can be used in two main ways:
- To access attributes and methods from the parent class
- To call the parent class constructor
Access Parent Methods
If a subclass has a method with the same name as one in its parent class, you can use super to call the parent version:
Example
class Animal {
public void animalSound() {
System.out.println("The animal makes a sound");
}
}
class Dog extends Animal {
public void animalSound() {
super.animalSound(); // Call the parent method
System.out.println("The dog says: bow wow");
}
}
public class Main {
public static void main(String[] args) {
Dog myDog = new Dog();
myDog.animalSound();
}
}Note
Use super when you want to call a method from the parent class that has been overridden in the child class.
Access Parent Attributes
You can also use super to access an attribute from the parent class if they have an attribute with the same name:
Example
class Animal {
String type = "Animal";
}
class Dog extends Animal {
String type = "Dog";
public void printType() {
System.out.println(super.type); // Access parent attribute
}
}
public class Main {
public static void main(String[] args) {
Dog myDog = new Dog();
myDog.printType();
}
}Call Parent Constructor
Use super() to call the constructor of the parent class. This is especially useful for reusing initialization code.
Example
class Animal {
Animal() {
System.out.println("Animal is created");
}
}
class Dog extends Animal {
Dog() {
super(); // Call parent constructor
System.out.println("Dog is created");
}
}
public class Main {
public static void main(String[] args) {
Dog myDog = new Dog();
}
}Note
The call to super() must be the first statement in the subclass constructor.