Java is an object-oriented, case sensitive and class based programming language. It strictly follows the concept of OOPs(Object oriented programming language). The byte code provided by the JVM enables a programmer to type the code once and run on any machine later which makes it a platform independent language.
A lambda expression is a piece of code that is giving an alternative way to the anonymous class to pass the function as a parameter to other subsequent flows of code such as methods, constructors, etc.. In this approach, a function can be referenced with a variable and passed as a reference to be executed in a subsequent flow of code execution.