What is JAVA Lambda Expression???

Java Lambda expressions are a new and important feature included in Java SE 8. A lambda expression provides a way to represent one method interface using an expression. A lambda expression is like a method, it provides a list of formal parameters and a body (which can be an expression or a block of code) expressed in terms of those parameters.

Lambda expressions also improve the Collection libraries. Java SE 8 added two packages related to bulk data operations for Collections, the java.util.function package, and the java.util.stream. A stream is like an iterator, but with a lot of extra functionality. Taken together, lambda expressions and streams are the biggest change to Java programming since the generics and annotations were added to the language.