https://www.baeldung.com/java-9-modularity
A Module is a group of closely related packages and resources along with a new module descriptor file.
In other words, it’s a “package of Java Packages” abstraction that allows us to make our code even more reusable.
java --list-modules lists the default java modules.
https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html
Lambda expressions are anonymous methods (methods without names) used to implement a method defined by a functional interface. A functional interface (java.util.function) is an interface that contains one and only one abstract method.
Java 8 introduces “Default Method” or (Defender methods) new feature, which allows developer to add new methods to the interfaces without breaking the existing implementation of these interfaces.
After introducing Default Method, it seems that interfaces and abstract classes are same. However, they are still a different concept in Java 8.
Abstract class can define constructor. They are more structured and can have a state associated with them. While in contrast, default method can be implemented only in the terms of invoking other interface methods, with no reference to a particular implementation's state. Hence, both are used for different purposes and choosing between two really depends on the scenario context.