I was trying to learn Lambdas and Method Reference.
The following code with BiConsumer Interface that create a List and copy it's content into Map's value... It works vary well when I run with the Lambda syntax (if I run with the commented Lambda stetment). But when I try with the Method Reference it give me a compile time error Incompatible types: invalid method reference for System.out::println. What is wrong here? Does it possible with Method Reference?