An abstract class is a java class that has one or more abstract methods (nobody). It cannot be instantiated and defines an interface that has to be implemented by all its subclasses.
Abstract classes vs. Interfaces
The below table shows the difference between abstract classes and Interfaces in Java.
| Field | Abstract Class | Interface |
|---|---|---|
| Method Type | Abstract ,Non-Abstract ,default and Static | Abstract Method |
| Final Variable | final and non-final variable | Variables final by Default |
| Variable Type | final, non-final, static and non-static variables | only static and final variables |
| Access Modifiers | It can have class members like private, protected, etc. | All the Members of a Java interface are public by default |
| Keywords | abstract class can be extended using keyword “extends”. | A Java interface can be implemented using keyword “implements” |
| Implementation | An abstract class can provide the implementation of the interface. | Interface can’t provide the implementation of an abstract class. |
| Multiple Implementation | An abstract class can extend another Java class and implement multiple Java interfaces | An interface can extend another Java interface only . |