Abstract Classes vs Interfaces in Java

In Java, abstract classes and interfaces are both used to achieve abstraction and define common behavior in object-oriented programming. However, there are some key differences between the two:

Abstract Classes:

• Can have both abstract and non-abstract methods.
• Can have member variables.
• Can provide a partial implementation of the interface.
• Used when you want to provide a common base implementation for subclasses.

Interfaces:

• Can only have abstract methods by default (from Java 8, interfaces can have default and static methods).
• Cannot have member variables.
• Used to define a contract for classes to implement.
• Supports multiple inheritance in Java.

When to Use Each One:

Use abstract classes when you want to provide a common base implementation for multiple subclasses. Use interfaces when you want to define a contract for classes to implement, especially when supporting multiple inheritance or when a class needs to implement functionality from multiple sources.

It's important to choose the right approach based on the specific design requirements of the project to ensure code maintainability and flexibility.