When do I use super()?
I'm currently learning about class inheritance in my Java course and I don't understand when to use the super()
call?
Edit:
I found this example of code where super.variable
is used:
class A
{
int k = 10;
}
class Test extends A
{
public void m() {
System.out.println(super.k);
}
}
So I understand that here, you must use super
to access the k
variable in the super-class. However, in any other case, what does super();
do? On its own?
Calling exactly super()
is always redundant. It's explicitly doing what would be implicitly done otherwise. That's because if you omit a call to the super constructor, the no-argument super constructor will be invoked automatically anyway. Not to say that it's bad style; some people like being explicit.
However, where it becomes useful is when the super constructor takes arguments that you want to pass in from the subclass.
public class Animal {
private final String noise;
protected Animal(String noise) {
this.noise = noise;
}
public void makeNoise() {
System.out.println(noise);
}
}
public class Pig extends Animal {
public Pig() {
super("Oink");
}
}
super
is used to call the constructor
, methods
and properties
of parent class.