An overview of abstract class in Java
The principle of object-oriented programming that "shows" only important attributes and "hides" unnecessary information is an abstraction. The main aim of abstraction is to hide the users' unnecessary data. Abstraction is selecting data from a wider pool in order to display the user only specific object information. It assists in reducing the difficulty and commitment to programming. It is one of the most significant OOPs definitions.
In JAVA, abstraction displays only the important features and hides from the user unnecessary information of the object. Abstraction is achieved in Java training using the Abstract class, Abstract methods, and Interfaces. Abstraction leads to reducing complexity and commitment to programming.
What is Abstract class in Java?
ABSTRACT CLASS is a type of Java class that declares one or more methods of abstraction. As well as concrete methods, these groups may have abstract methods. A typical class is unable to provide abstract methods. A class that includes at least one abstract method is an abstract class. By the shape example in java, we can comprehend the definition.
The Shape class is designed to store common attributes and techniques shared by the three Rectangle, Circle, and Triangle classes. One such method shared by all three child classes and present in the Shape class is calculateArea().
What are Approaches for Abstract?
The Abstract Method is a method that has only the description of the method but does not include execution. An Abstract Method is called a method without a body. In an abstract class, it must be declared. The abstract technique can never be final since all the abstract techniques must be applied by the abstract class.
Abstraction Advantages in Java
The key advantage of using an abstract in programming is that it allows many similar groups to be grouped as siblings.
Abstraction in Object-Oriented Programming tends to decrease the difficulty of the software design and development process.
When to use Abstract & Abstract Class Methods?
Mostly, abstract methods declare two or more subclasses by different implementations also do the same thing in different ways. It also extends the same Abstract class and provides numerous abstract method implementations.
Abstract classes help to define the hierarchy of generic activity types and object-oriented programming classes. In order to provide implementation specifics of the abstract class, it also defines subclasses.
Example
For example, let's study abstraction in OOPs:
Suppose you want a banking application to be produced and you are asked to collect all your client's information. Chances are that you can come up with the following customer details.
But in order to construct a banking application, not all of the information above is needed.
So, you just need to pick valuable details from the pool for your banking application. For a banking application that is an abstraction example in OOPs, data such as name, address, tax details, etc. make sense.
Abstraction in Java
Since we have collected/removed/selected customer data from a wider pool, the approach is referred to in OOPs as Abstraction.
The same data once extracted can however, be used for a wide variety of applications. For example, with little to no alteration, you can use the same data for a hospital application, work portal application, government database, etc. It becomes, therefore, your Master Data. This is an advantage of OOPs for Abstraction.
An Instance of Form Abstraction in Java
Now, presume that you're writing code to build objects for the classes shown above. Let's observe in a practical environment how these objects would appear.
A rectangle will give an object of the class rectangle, a form that we have so often seen in daily life.
A triangle, again a common everyday type, will be given by an object of the class triangle.
But what does a Class Shape entity look like in a world of practice??
If you obey the Shape class, our aim is to achieve inheritance and polymorphism. But it was not designed in order to be instantiated. It is possible to call such groups abstract. It is difficult to instantiate an abstract Java online course class.
Syntax:
Shape{ abstract class
Code /
}
You do NOT mark the Shape class as Abstract and instantiate it afterward. But in your code, such an object will have no use and will open a room for possible mistakes. This is therefore not desirable.
What are Approaches for Abstract in Java?
In Java, ABSTRACT METHOD is a technique that has only the description of the method but does not require implementation. An Abstract Method is called a method without a body. In an abstract class, it must be declared. The abstract technique can never be final since all the abstract techniques must be applied by the abstract class.
The formula for measuring the rectangle, circle, & triangle area is different, as we all know. The inheriting classes will have to override the calculateArea() method. In the Shape class, it doesn't make sense to describe it, but we need to make sure that all the heritage classes have the technique.
It is possible to class such techniques abstract.
Syntax:
CalculateArea() abstract public void;
No implementation is required for an abstract method. Only the method's signature is specified.
Example of Abstraction Code
Shape{ abstract class
CalculateArea() abstract void;
}
Public Class extends Shape{
Void calculateArea(){System.out.println("Area of Shape");};{System.out.println("Area of Shape");}
Static public void main(String args[]){
Form obj = fresh();
(); obj.run();
}
}
Essential Points In Java Abstract Class
- There may also be concrete (complete) methods for an abstract class.
- A class can be declared abstract for design purposes, even though it does not include any abstract methods.
- An abstract class reference may point to objects of its sub-classes, thus achieving polymorphism of runtime Ex: Shape obj = new Rectangle();;
- If it has one or more abstract processes, a class must be forcefully called abstract.
The Final Keyword in Java
For classes, processes, and variables, the final modifier applies. The sense of the end differs from context to context, but it is the same as the basic concept.
Unable to inherit a final class
A final variable becomes a constant and it is not possible to change its value.
It is not possible to bypass the final process. For security purposes, this is achieved, and for optimization, these approaches are used.
Example:- Abstract & final keywords to learn in Java
Step 1)
Copy to the Editor with the following code.
Shape{ abstract class
Int final b = 20;
Public Void Viewer(){{
System.out.println('This is the method of display');
}
CalculateArea() abstract public void;
}
Public Rectangle Class Extends Shape{
Static public void main(String args[]){
Item rectangle = new Rectangle();
();; obj.display();
B=200; /obj.b=200;
}
/public void calculateArea(){}} @public void calculateArea()
}
Step 2)
Save the code, Compile & Run.
Step 3)
Error =? The abstraction mechanism is not implemented in the Rectangle class. Uncomment line #15 to fix the problem.
Step 4)
Line of Uncomment # 13 . Code Save & Compile.
Step 5)
Fehler =? Variable “b” is final,
Abstract Process Rules in Java
There is no implementation of abstract methods. It just has a method signature
If an abstract method is used by a class, it must be declared abstract. The reverse can't be accurate. This implies that there is not inherently an abstract method for an abstract class.
If an abstract class is expanded by a standard class, then that class must follow all the abstract methods of the abstract parent class.
Conclusion
I hope you find this article enlightening about Abstract class in Java. You can learn other topics in detail through Java online training.