Using the super Keyword to Call a Base Class Constructor in Java
We prefer inheritance to reuse the code available in existing classes. In Java, Inheritance is the concept in which one class inherits the properties of another class. In the below example there are two classes Programming and DP while Programming is Parent class and DP is child class. From the main class, we have created an object of DP i.e. child class as it also allows us to access the methods from its parent class, but if we create an object of Parent class(Programming) then we cannot access the methods or objects from its child class.
After creating an object of child class we have first called a method from child class and then called a method from the parent class. This doesn’t matter as we can call the objects in any order.
In the below example, we have created a parent and child class. Here, we have created an object of the child class, as the constructor will call itself on creating an object we need not mention anything.
After creating an object of child class the constructor is expected to print the output from its own class, but from the output, we can identify that Parent class got executed and then child class got executed, this is because we have created a constructor for inherited class and every class contains a super() by default, as we are calling an inherited class it contains super() in its first line and calls the Parent class.
In the below example we have used the constructor overloading concept, and we have created an object of child class and after calling the constructor of child class the first line in it is super(10, 20) which says that call the matching constructor from the parent class, if we do not mention that line, by default it calls the super() with no parameterized constructor from Parent class.
Programming + + DP
Let’s look at the below snippet,
- In the below code we have created an object of the child class, and we are passing the value of 10 from the object line itself and after going to the specific constructor it first calls super() by default and prints “Programming” from the Parent class.
- The point to note is here we are calling a parameterized constructor from the object creation line but it will call super() by default as will be available by default.
- In child class, we can also give super() with parameters to call a specific constructor from Parent class.
Programming DP +