How to Use Super in Java

Java is among the most popular programming languages, and for a good reason. It is versatile, efficient, and powerful, making it perfect for developing complex applications. One of the features that make Java a go-to language for developers is the ability to use the "super" keyword. In this article, we will explore what "super" is, how it works, and how to use it effectively.

Table of Contents

What is the "super" keyword in Java?

The "super" keyword in Java refers to the superclass or parent class of a derived or child class. In simpler terms, it is a reference to the class from which the current class is derived. The super keyword is used to call the parent class constructor, access the parent class method, and access the parent class variable.

When a class inherits from a parent class, it inherits all the properties and methods of the parent class, including the private ones. However, because private members of a class cannot be accessed from the derived class, the "super" keyword is used to access them.

How does the "super" keyword work?

When a class is derived from a parent class, it automatically inherits all the properties and methods of the parent class. However, there may be instances where the developer needs to override or modify some of the properties or methods inherited from the parent class. In such cases, the "super" keyword can be used to access the parent class properties or methods.

When the "super" keyword is used to call the parent class constructor, it must be the first line of code in the constructor of the derived class. This is because the parent class must be initialized before the derived class. The syntax for calling the parent class constructor using the "super" keyword is as follows:

public class ChildClass extends ParentClass {
    public ChildClass() {
        super();
    }
}

When the "super" keyword is used to access the parent class method, it can be used to call both the overridden and non-overridden methods of the parent class. The syntax for calling the parent class method using the "super" keyword is as follows:

public class ChildClass extends ParentClass {
    public void childMethod() {
        super.parentMethod();
    }
}

When the "super" keyword is used to access the parent class variable, it can be used to access both the private and non-private variables of the parent class. The syntax for accessing the parent class variable using the "super" keyword is as follows:

public class ChildClass extends ParentClass {
    public void childMethod() {
        int parentVariable = super.parentVariable;
    }
}

How to use "super" effectively

The "super" keyword can be used in different ways to enhance the functionality of a program. Here are some of the ways in which "super" can be used effectively:

1. Calling the parent class constructor

When a class is derived from a parent class, it automatically inherits the constructor of the parent class. However, if the constructor of the parent class has parameters, the derived class constructor must explicitly call the parent class constructor. This can be done using the "super" keyword.

2. Overriding parent class methods

A class derived from a parent class can override the methods of the parent class. In such cases, the "super" keyword can be used to call the parent class method and modify its behavior. This can be useful when the developer needs to add some functionality to the parent class method.

3. Accessing parent class variables

A class derived from a parent class can access the variables of the parent class using the "super" keyword. This can be useful when the derived class needs to modify or use the variables of the parent class.

4. Calling both the parent and child class methods

A class derived from a parent class can call both the parent and child class methods using the "super" keyword. This can be useful when the developer needs to access the functionality of both the parent and child classes.

5. Preventing name collisions

When a derived class has a method or variable with the same name as the parent class, the "super" keyword can be used to call the parent class method or access the parent class variable. This can be useful in preventing name collisions.

Conclusion

The "super" keyword is an essential feature of Java programming language that allows developers to access the functionality of the parent class from the derived class. It can be used to call the parent class constructor, access the parent class method, and access the parent class variable. By understanding how "super" works and how to use it effectively, developers can enhance the functionality of their programs and create more efficient and powerful applications.

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