Abstraction is one of the four fundamental object-oriented programming (OOP) principles in Java and other programming languages. It is a concept that allows you to represent complex real-world entities as simplified and essential models in your code. In Java, abstraction is achieved using abstract classes and interfaces.
Abstraction helps you create a blueprint or a set of rules for how objects of a certain type should behave without specifying the implementation details. This way, you can hide the internal complexity of an object, exposing only the necessary functionalities and behaviors to the outside world.
Here are the two main ways abstraction is implemented in Java:
- Abstract Classes: An abstract class is a class that cannot be instantiated directly. It serves as a base or blueprint for other classes and can contain both abstract and concrete (implemented) methods. Abstract methods are declared without a body and are meant to be implemented by the concrete subclasses that extend the abstract class. Subclasses must provide an implementation for all the abstract methods defined in the abstract class.
Example of an abstract class in Java:
abstract class Shape {
// Abstract method without implementation
public abstract double area();
// Concrete method
public void display() {
System.out.println("This is a shape.");
}
}2. Interfaces: An interface is a pure abstraction in Java, as it only contains method signatures (without implementations) and constants. Classes can implement multiple interfaces, allowing for multiple inheritance of behavior. When a class implements an interface, it must provide implementations for all the methods declared in that interface.
Example of an interface in Java:
interface Drawable {
void draw(); // Abstract method
}By using abstraction, you can create a clear separation between the interface of an object and its implementation details, making your code more flexible, maintainable, and easier to understand. It also allows you to work with a higher level of abstraction, focusing on the essential features of an object rather than getting lost in the implementation specifics.
