Super Class Parameterized Constructor in Java: How to Implement and Use

Java is a versatile and widely-used programming language, and one of its key features is inheritance. Inheritance allows one class to inherit the properties and methods of another class. One of the important aspects of inheritance is the super keyword, which allows you to refer to the parent class variables, constructors, and methods within the child class.

Understanding the Super Keyword

The super keyword in Java is used to refer to the parent class object of a current object, and can be used to access the variables and methods of the parent class. It’s a reference to the immediate parent class of the current class. Using the super keyword, you can explicitly call the constructor of the parent class, refer to the parent class variables, and call parent class methods.

How to Use the Super Keyword in Constructor

The super keyword can be used in constructors to call a parameterized constructor of the superclass. This is particularly useful when the constructor of the child class needs to initialize variables that are instances of the parent class.

In the following Java code, we define class A with a private instance variable int a, and a parameterized constructor to initialize this variable. Class B extends class A, and we use the super keyword in the constructor of B to call the parameterized constructor of class A with a specific value.

```java public class A { private int a; A(int a) { this.a a; ("Class A constructor"); } } public class B extends A { B() { super(11); ("Class B constructor"); } public static void main(String[] args) { B obj new B(); } } ```

Interpreting the Code

In the above code, Class A has a private instance variable a11 and a parameterized constructor that initializes this variable.

Class B is a subclass of A. The constructor of B uses the super(11) to call the parameterized constructor of A and pass the value 11. This allows class B to utilize the properties defined in class A through the inheritance mechanism.

When the main method is executed, an object of class B is created. Consequently, the output would be:

```java Class A constructor Class B constructor ```

Best Practices and Considerations

While using the super keyword in constructors, it's important to remember that the super constructor must be the first statement in the subclass constructor. Failure to do so will result in a compilation error.

It's also important to ensure that the parameters passed to the super parameterized constructor match the parameters of the parent class constructor. If the parameters do not match, a compilation error will occur. Always ensure to initialize the superclass variables before using them in the subclass.

Conclusion

By understanding and effectively utilizing the super keyword in Java, developers can create efficient and maintainable code. Learning to use the super parameterized constructor properly is a crucial skill for anyone working with the Java programming language and can significantly enhance the functionality of your application.

Related Keywords

super class constructor parameterized constructor Java inheritance

About the Author

This article was written by a seasoned Java developer with extensive experience in software development. If you have any questions about this topic or need assistance with Java programming, feel free to reach out for further assistance.