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Concrete Class in Java

Java offers a potent feature known as classes for object-oriented programming. An object may be created using a class as a blueprint since it has both data and behaviour. There are concrete classes that may be instantiated directly in addition to abstract classes that define shared traits and behaviours for subclasses. The properties, advantages, and use examples of Java's concrete classes will all be covered in this article.

What is a Concrete Class?

In Java, a concrete class is one that can be instantiated to produce objects. All of its methods, including abstract ones inherited from superclasses or interfaces, have full implementations provided by this class. A concrete class is one that has all of its abstract methods implemented, to put it another way.

Concrete Class Characteristics

Concrete classes can be created by using the "new" keyword to construct objects, which is known as direct instantiation.

  • Complete Implementation:

Concrete classes offer full implementations for each and every one of their methods, even those that are inherited from parent classes or interfaces. They provide certain functionality that may be used without any additional alterations.

  • Concrete classes can define instance variables, methods, constructors, and they can take part in inheritance hierarchies. These are examples of object-oriented features. They can also put interfaces into place, adding to their versatility and guaranteeing contract adherence.

The Advantages of Concrete Classes

  1. Reusable code is contained into concrete classes, making it simple to construct objects with predetermined behaviour and properties. Because the same class may be created more than once with different data, this encourages code reuse.
  2. Concrete classes are simpler to maintain than abstract classes since they offer comprehensive implementations. Without modifying the entire inheritance structure, any changes or improvements may be applied directly within the class.
  3. Improved Readability: Behaviour and functionality are defined explicitly and clearly via concrete classes. Since developers can now easily access and comprehend the implemented methods, the readability of the code is improved, and ambiguity is decreased.


Length: 5.0
Width: 3.0
Area: 15.0
Perimeter: 16.0
Length: 7.0
Width: 4.0
Area: 28.0
Perimeter: 22.0


In this example, the Rectangle class represents a concrete class with two private instance variables: length and width. It has a constructor that takes the initial values for length and width as parameters.

The length and width variables may be accessed and changed using the class's getter and setter methods. By multiplying the length and width, the calculateArea() function determines and returns the area of the rectangle. The perimeter of the rectangle is calculated and returned by the calculatePerimeter() function.

The aforementioned code produces a Rectangle class object with the default length and width of 5.0 and 3.0, respectively. The rectangle's length, breadth, area, and perimeter are then printed. The new numbers are printed when the length and width have been changed using the setter methods, and the area and perimeter have been recalculated.


Java's concrete classes are essential for object-oriented programming. They give full implementations of its methods, are immediately instantiated, and make code reuse and maintenance easier. Developers may create and deploy reliable and adaptable Java programmes by effectively knowing the features and advantages of particular classes.

When you have a precise implementation in mind and wish to provide your class's users a clear contract, keep in mind that concrete classes should be utilised. However, abstract classes or interfaces could be a better choice if you need to provide common traits and behaviours for several subclasses.

You may use the power of Java's object-oriented capabilities to construct effective and well-structured programmes by learning the idea of concrete classes.

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