What is the Difference Between Abstract Class and Concrete Class?
🆚 Go to Comparative Table 🆚The main difference between an abstract class and a concrete class in Java is that an abstract class can have abstract methods, while a concrete class cannot. Here are some key differences between the two:
- Abstract Class:
- Declared using the
abstract
keyword. - Can have both abstract and concrete methods.
- Cannot be directly instantiated using the
new
keyword. - Must be inherited by a concrete subclass or implemented by an interface.
- Cannot implement an interface alone; a child class is needed for instantiation.
- Cannot be declared as
final
. - Concrete Class:
- Not declared using the
abstract
keyword. - Can only have concrete methods; even a single abstract method makes the class abstract.
- Can be directly instantiated using the
new
keyword. - Implements all the abstract methods of its parent abstract class.
- Can implement interfaces.
- Can be declared as
final
.
In summary, an abstract class is a blueprint for concrete classes, containing abstract methods that must be implemented by subclasses. A concrete class, on the other hand, is a fully implemented class that implements all the methods, including those inherited from abstract classes or interfaces.
Comparative Table: Abstract Class vs Concrete Class
Here is a table comparing the differences between abstract classes and concrete classes:
Feature | Abstract Class | Concrete Class |
---|---|---|
Keyword | Declared with the abstract keyword |
Not declared with the abstract keyword |
Instantiation | Cannot be directly instantiated using the new keyword |
Can be directly instantiated using the new keyword |
Abstract Methods | May or may not contain abstract methods | Cannot contain abstract methods |
Final | Cannot be declared as final | Can be declared as final |
Inheritance | Can inherit from another class using the extends keyword and implement an interface |
Cannot inherit from another class using the extends keyword, but can implement an interface |
Interface Implementation | Cannot implement an interface alone; a child class is needed for instantiation | Can implement an interface directly |
Methods | Can have both abstract and concrete methods | Can only have concrete methods |
In summary, abstract classes can contain abstract methods and can inherit from other classes or implement interfaces, but they cannot be directly instantiated. Concrete classes, on the other hand, do not contain abstract methods and can be directly instantiated. They can also be declared as final and implement interfaces directly.
- Abstract Class vs Interface
- Abstract Class vs Inheritance
- Abstract vs Concrete Thinking
- Virtual vs Abstract
- Class vs Interface
- Encapsulation vs Abstraction
- Abstract vs Introduction
- Objects vs Classes
- Abstract vs Summary
- Classes vs Structures
- Superclass vs Subclass
- Adjective vs Abstract Noun
- Abstract vs Preface
- Cement vs Concrete
- Class vs Instance Variables
- Class Diagram vs Object Diagram
- Abstract vs Executive Summary
- Mortar vs Concrete
- Constructor vs Destructor