Important Points: Interfaces can have default methods with implementation in Java 8 on later. Interfaces can have static methods as well, similar to static methods in classes. Default methods were introduced to provide backward compatibility for old interfaces so that they can have new methods without affecting existing code.

Java introduced a new concept of default method implementation in interfaces in Java 8. Prior to Java8, an interface could have only abstract methods. Default method capability was added for backward compatibility so that old interfaces could be used to leverage the lambda expression capability of Java 8.

Interface default methods are by default available to all implementation classes. Based on the requirement, an implementation class can use these default methods directly or override them. System.out.println("Default Method"); example.m1(); Default methods are also known as defender methods or virtual extension methods.

Thus, adding such method will simply break the collection framework implementations. Java 8 introduces default method so that List/Collection interface can have a default implementation of forEach method, and the class implementing these interfaces need not implement the same. The following is the syntax of the default method in interface in Java -