Java 8 : Default Interface Methods or Abstract Class Methods—When to Choose Which?

Interface Default Methods vs. Abstract Class Abstract Methods in Java 8

Java 8 introduced interface default methods to provide default implementations for interface methods. This raises the question: when should default methods be used instead of abstract classes with abstract methods?

Using Default Methods

Default methods are best suited for:

• Creating higher-level convenience methods that do not rely on the specific implementation of the receiving class.
• Extending existing interfaces without breaking compatibility with current implementations.
• Providing minimal implementation effort for method bodies.

Using Abstract Classes

Abstract classes remain useful when:

• Private data is needed in the implementation of the methods.
• Default methods cannot fully implement the desired functionality and require further customization within derived classes.
• A superclass constrains the implementation of the abstract method(s).

Choosing Between Default Methods and Abstract Classes

When possible, prefer default methods over abstract classes. Default methods provide greater flexibility by:

• Allowing multiple interfaces with default methods to be implemented in a single class (without the single inheritance limitation of abstract classes).
• Enabling dynamic changes to method implementation at runtime using lambda expressions.
• Simplifying the design by keeping essential implementation logic separate from the interface definition.

In cases where private data is required or the functionality demands customization, abstract classes may still be appropriate.

The above is the detailed content of Java 8 : Default Interface Methods or Abstract Class Methods—When to Choose Which?. For more information, please follow other related articles on the PHP Chinese website!