Java interfaces are an essential component of the Java programming language. They allow developers to define a set of methods that a class must implement, providing a level of standardization and compatibility between different classes. However, when it comes to declaring methods within interfaces, there is a key distinction between public and non-public methods. In this article, we will explore the differences between these two types of method declarations in Java interfaces.
Firstly, let's define what a public method is. In Java, a public method is one that can be accessed by any class. This means that any class implementing the interface can call and use the public method. On the other hand, a non-public method, also known as a default or package-private method, can only be accessed by classes within the same package as the interface.
The most significant difference between public and non-public methods in interfaces is their level of accessibility. Public methods are accessible to all classes, making them widely available for use. Non-public methods, on the other hand, are only accessible within a restricted scope, meaning they have limited usage.
One might wonder why non-public methods even exist in interfaces if they have such limited accessibility. The answer lies in the concept of encapsulation. Encapsulation is a fundamental principle of object-oriented programming that involves hiding the internal workings of a class from external access. By declaring non-public methods in an interface, developers can restrict access to certain methods, thus promoting encapsulation.
Another crucial distinction between public and non-public methods in interfaces is their role in inheritance. When a class implements an interface, it must implement all the public methods defined in the interface. This is because public methods are considered part of the interface's contract, and all implementing classes must adhere to this contract. On the other hand, non-public methods are not part of the interface's contract and are, therefore, not required to be implemented by the implementing class.
Furthermore, public methods in interfaces can be overridden by implementing classes, whereas non-public methods cannot. This is because non-public methods are not visible outside the interface's package, and thus cannot be accessed by the implementing class.
So, which type of method should you choose when declaring methods in your Java interfaces? The answer depends on your specific needs. If you want a method to be widely accessible and part of the interface's contract, then a public method is the way to go. On the other hand, if you want to restrict access to a method and promote encapsulation, then a non-public method is the better option.
In conclusion, both public and non-public methods have their uses in Java interfaces. Public methods offer wide accessibility and are part of the interface's contract, while non-public methods promote encapsulation and have limited accessibility. As a developer, it is essential to understand the differences between these two types of method declarations and choose the one that best suits your needs.
