Blog
What is Abstract class and Method in Java?
- August 29, 2024
- Posted by: Riddhi Dhandha
- Category: Advanced java Java course at TCCI Online Computer Coaching Programming Language Course
In Java, an abstract class and an abstract method are key concepts in object-oriented programming, used to define classes and methods that are meant to be extended or overridden in subclasses. Here’s a breakdown:
Abstract Class
- Definition: An abstract class in Java is a class that cannot be instantiated directly. It is used as a base class for other classes to inherit from. Abstract classes are defined using the abstract
- Purpose: Abstract classes are designed to be inherited by subclasses that provide specific implementations for its abstract methods. They can contain both abstract methods (methods without a body) and concrete methods (methods with a body).
- Usage: Abstract classes are often used when there are some shared features among different classes, but the implementation of certain methods should be left to the subclasses.
JavaCopy codeabstract class Animal { abstract void sound(); // Abstract method void breathe() { // Concrete method System.out.println(“This animal breathes air.”); }}
Abstract Method
- Definition: An abstract method is a method that is declared without an implementation (no method body) in an abstract class. It is meant to be overridden by subclasses that inherit the abstract class.
- Purpose: Abstract methods define a method signature that must be implemented by any concrete subclass, enforcing a certain contract or behavior.
- Usage: When a subclass extends an abstract class, it must provide an implementation for all abstract methods of the parent class, unless the subclass is also declared abstract.
javaCopy codeclass Dog extends Animal { void sound() { // Implementing the abstract method System.out.println(“Woof”); }}
Example
Here’s how an abstract class and method might be used:
javaCopy codeabstract class Vehicle { abstract void start(); // Abstract method void stop() { // Concrete method System.out.println(“Vehicle stopped.”); }} class Car extends Vehicle { @Override void start() { // Implementing the abstract method System.out.println(“Car started with key.”); }} class Bike extends Vehicle { @Override void start() { // Implementing the abstract method System.out.println(“Bike started with button.”); }}
In this example:
- Vehicle is an abstract class with an abstract method start().
- Car and Bike are concrete subclasses that provide their own implementations of the start() method.
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