Abstraction in Java
Abstraction in Java is the process of simplifying complex systems by hiding unnecessary details and exposing only essential features or functionalities. It focuses on the "what" rather than the "how" of a system.
In Java, abstraction is achieved through abstract classes and interfaces. Abstract classes provide a blueprint for other classes to inherit from, and interfaces define a contract that implementing classes must adhere to.
By using abstraction, you can create reusable code components and establish a clear separation between the interface and implementation of a system. This makes the code more maintainable, extensible, and easier to understand.
In essence, abstraction in Java allows you to represent complex real-world entities or systems in a simplified and manageable way, providing a high-level view while hiding the implementation details.
In Java, the keyword "abstract" is used to declare a class or a method as abstract. Let's look at what it means in both cases:
- Abstract Classes:
An abstract class is a class that cannot be instantiated directly. It serves as a blueprint for other classes to inherit from. It may contain abstract methods, concrete methods, and member variables. An abstract method is a method that is declared but does not have an implementation in the abstract class. Subclasses that extend the abstract class are required to provide an implementation for all the abstract methods. However, they can also override and provide their own implementation for the concrete methods.
To declare an abstract class, you use the "abstract" keyword in the class declaration, like this:
public abstract class AbstractClass {
// abstract methods and/or concrete methods
}- Abstract Methods:
An abstract method is a method that is declared without an implementation in an abstract class or an interface. It provides a contract for the subclasses to implement. Subclasses that extend the abstract class or implement the interface must provide an implementation for all the abstract methods declared.
public abstract void methodName();Abstract methods do not have a body and end with a semicolon instead of curly braces. They are meant to be overridden by the subclasses to provide their own implementation.
It's important to note that abstract classes cannot be instantiated, but they can be used as a reference type, allowing you to create variables of the abstract class type and store instances of its concrete subclasses.