An abstract class in Java is a class that is proclaimed with the “abstract” keyword. It serves as a blueprint for other classes and can contain abstract methods (methods without a body) and non-abstract methods (methods with a body). Before delving into the concept of an abstract class in Java, it’s important to grasp the idea of abstraction in Java. we are also offering Java developer course Online to upskill your knowledgeÂ
Abstraction in Java simplifies complex systems by focusing on important features and hiding irrelevant details. It allows us to create generalized classes and methods others can extend and implement. Abstraction helps in designing more manageable and modular code.
Now, with this understanding of abstraction, we can explore the Java abstract class, which is a special type of class that encapsulates common features and behaviors to be inherited by its subclasses. The abstract class in Java can have abstract methods that provide a declaration without an implementation and non-abstract methods that contain the actual code.
By using abstract classes, we can establish a foundation for other classes to build upon, promoting code reusability and providing a clear structure for the overall program.
Abstraction in Java
Abstraction is a powerful concept in programming that involves hiding the complex inner workings of a system and presenting only the essential functionalities to the user.
Think of it like sending an SMS. When you compose a text message and hit send, you don’t need to know the intricate details of how the message gets delivered to the recipient. All you care about is that the message is sent successfully. This is an abstraction in action—showing you what you need to know (the functionality) while keeping the inner workings (the implementation) hidden.
In simple terms, abstraction allows us to focus on the important aspects of a system without getting caught up in the nitty-gritty details. It simplifies the user experience and promotes better code organization and reusability. We can create more user-friendly and efficient applications by utilizing abstraction in programming.
Ways to achieve abstraction
There exist two ways to declare abstraction in Java
- Abstract class (0 to 100%)
- Interface (100%)
Abstract Class in Java
An abstract class in Java is a class that is specifically marked as “abstract.” It serves as a blueprint for other classes and can contain abstract methods (methods without implementation) and non-abstract methods (methods with implementation).
Here are some important points to remember about abstract classes: Declaration: An abstract class in Java must be declared using the “abstract” keyword.
Abstract and Non-Abstract Methods: It can have both abstract and non-abstract methods. Abstract methods are like placeholders that provide a declaration without an actual implementation, while non-abstract methods have a defined body with the code.
No Instantiation: Abstract classes in Java cannot be directly instantiated, which means you cannot create objects of an abstract class. It is expected to be extended by other classes implementing its abstract methods.
Constructors and Static Methods: Abstract classes can have constructors and static methods, just like any other class in Java.
Final Methods: Abstract classes can have final methods. When a method is marked as final in an abstract class, the subclass cannot override or change the implementation of that particular method.
Understanding these key points about abstract classes in Java helps design class hierarchies, promotes code reusability, and defines contracts for subclasses to follow.
Examples of Abstract class that has an abstract method
abstract class Bike{Â Â
  abstract void run(); Â
}Â Â
class Honda4 extends Bike{Â Â
void run(){System.out.println(“running safely”);}Â Â
public static void main(String args[]){Â Â
 Bike obj = new Honda4(); Â
 obj.run(); Â
}Â Â
}Â Â
Output:
Compile by: javac Honda4.java
Run by: java Honda4
Understanding the Real Scenario of Abstract ClassÂ
In this example, we have an abstract class in Java called Shape, which serves as a blueprint for other classes. The specific implementation details of Shape are hidden from the end user. Instead, the user interacts with the implementation classes like Rectangle and Circle.
To create instances of these implementation classes, a factory method is used. A factory method is a special method that returns an object of a specific class. It handles the creation of objects and provides them to the user.
In this example, if you create an instance of the Rectangle class, the draw() method defined in the Rectangle class will be executed. The draw() method contains the code for drawing a rectangle on the screen or performing any other specific action associated with rectangles.
By utilizing abstract classes and factory methods, we can encapsulate the implementation details and provide a simplified interface for the user to work with different shapes.
Frequently Asked Questions
Q1. In Java, what’s the meaning of abstraction?Â
Ans. The abstract keyword is a non-access modifier used for classes and methods. An abstract class is a restricted class that cannot be used to create objects (to access it, it must be inherited from another class). Abstract method: this can only be used in an abstract class and doesn’t have a body.
Q2. What’s the point of using an abstract in Java?Â
Ans. The Abstract class in Java allows developers to hide code implementation, which makes it possible to perform this data abstraction process best. A template explaining how the methods are implemented is also presented to the end user.
Q3. What is abstraction and its types? What are they?
Ans. An abstract is classified into four categories: informative, descriptive, critical, and highlight. The most common uses by students are informative abstracts. It is to be noted that you must always follow the instructions prescribed by your teacher or institution.
