What is the difference between an abstract class and an interface in Java?

Question

Ravi Vishwakarma · Answer

Abstract Classand 
An 
abstract class is a class that cannot be instantiated on its own and may contain abstract methods (methods without a body) and non-abstract methods (methods with a body).
Usage: Used when you want to provide a common base class for other classes to extend, while also providing some shared implementation.
Exampleand 
public abstract class Animal {
 private String name;
 public Animal(String name) {
 this.name = name;
 }
 public String getName() {
 return name;
 }
}
Interface
An 
interface is a reference type in Java that is used to specify a set of abstract methods that a class must implement. From Java 8 onwards, interfaces can also contain default and static methods with implementations.
Usage: Used to define a contract that other classes must follow. Interfaces are typically used to represent capabilities or behaviors that can be shared across different classes.
Exampleand 
public interface Animal {
 void makeSound(); // Abstract method
 default void eat() {
 System.out.println("This animal eats food."); // Default method
 }
}
Key Differences
Feature
Abstract Class
Interface
Methods
Can have both abstract and concrete methods
Can have abstract methods, default methods, and static methods
Fields
Can have instance variables
Can only have public static final fields (constants)
Inheritance
Supports single inheritance
Supports multiple inheritance
Constructors
Can have constructors
Cannot have constructors
When to Use
Use when classes share a common base class
Use to define a contract that multiple classes can implement
Read moreand 
When to use Interface?
What's the difference between an Abstract Class and an Interface in Java?
What is the purpose of an interface in OOP?
and 
and

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What is the difference between an abstract class and an interface in Java?

Ravi Vishwakarma

1 Answers

Abstract Class

Interface

Key Differences

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Feature	Abstract Class	Interface
Methods	Can have both abstract and concrete methods	Can have abstract methods, default methods, and static methods
Fields	Can have instance variables	Can only have public static final fields (constants)
Inheritance	Supports single inheritance	Supports multiple inheritance
Constructors	Can have constructors	Cannot have constructors
When to Use	Use when classes share a common base class	Use to define a contract that multiple classes can implement