Understanding the 'super' Keyword in Java

The 'super' keyword in Java plays a critical role in relations between classes, particularly in the context of inheritance. In Java, 'super' is primarily used to call a method of the superclass.

To appreciate the importance and usage of the 'super' keyword, one must understand Java's inheritance concept. Inheritance allows one class (subclass) to inherit fields and methods from another class (superclass). This not only promotes reuse of code but also establishes an 'is-a' relationship between the classes, thereby offering a hierarchy structure in object-oriented programming.

Calling a Superclass Method Using 'super'

When we have a method in a subclass that is also present in the superclass, we often need the 'super' keyword. It comes in handy when we want to access and invoke the superclass's version of the method. Consider the following example:

class SuperClass {
    void display() {
        System.out.println("This is the superclass's display method");
    }
}

class SubClass extends SuperClass {
    void display() {
        super.display(); // Call to superclass's display method
        System.out.println("This is the subclass's display method");
    }
}

In this example, the SubClass has a method named display() that is also present in its superclass, SuperClass. When we create an instance of SubClass and call its display() method, we first use super.display() to call the display() method of the superclass. This ensures that we execute both versions of the display() method.

Best Practices and Additional Insights

While using the 'super' keyword is straightforward, a few best practices can optimize the keyword's use. Firstly, avoid unnecessary usage of 'super'. If a method isn't overridden in a subclass, Java will automatically use the superclass method. Here, there's no need to use 'super' explicitly.

Secondly, use 'super' to call the superclass constructor. This practice is fundamental in some cases, such as when the superclass doesn't have a no-argument constructor. In these cases, Java requires an explicit call to the superclass's constructor using the 'super' keyword.

In conclusion, the 'super' keyword in Java provides a way to access methods from the superclass, fostering code reusability and the hierarchal arrangement of classes in Java's object-oriented paradigm.