When to use: Java 8+ interface default method, vs. abstract method

Question

Java 8 allows for default implementation of methods in interfaces called Default Methods.

I am confused between when would I use that sort of interface default

Answer 1

There are a few technical differences. Abstract classes can still do more in comparison to Java 8 interfaces:

1. Abstract class can have a constructor.
2. Abstract classes are more structured and can hold a state.

Conceptually, main purpose of defender methods is a backward compatibility after introduction of new features (as lambda-functions) in Java 8.