Default Methods vs. Abstract Methods: When to Choose Which in Java?

Interface Default Methods vs. Abstract Class Abstract Methods

Java 8's default methods in interfaces enable method implementation within the interface itself. This has raised confusion about the circumstances where default methods should be employed in place of an abstract class with abstract methods.

When to Use Default Methods:

Default methods in interfaces are suitable for higher-level and convenience methods that can be implemented solely by calling other interface methods. They are utilized to:

• Extend interfaces with lambda-oriented methods without disrupting existing implementations.
• Provide default implementations of common behaviors that can be overridden by implementing classes.
• Encapsulate reusable functionality without introducing inheritance constraints.

When to Use Abstract Classes:

Abstract classes remain useful for scenarios beyond default method implementations. They provide:

• Encapsulation of private state
• Multiple inheritance (by implementing multiple abstract classes)
• Control over abstract method visibility (protected, public)
• Mixed abstract and concrete methods to offer flexibility in subclassing

In summary, if the desired functionality can be achieved within the constraints of default methods, it is preferable to use the default method in the interface for its simplicity and lack of inheritance constraints. However, abstract classes remain essential for situations where state, multiple inheritance, or complex method visibility control is required.

The above is the detailed content of Default Methods vs. Abstract Methods: When to Choose Which in Java?. For more information, please follow other related articles on the PHP Chinese website!