Java 8 Lambda Expressions

Why Java needs Lambda Expressions?

Since its beginning, the Java language hasn’t evolved much if you ignore some of the features like Annotations, Generics etc. Mostly during its life Java always remained Object first language. After working with functional language like JavaScript, it becomes clear to one how Java enforce its strict object-oriented nature and strict typed on the source code. You see Functions are not important for Java. On their own they cannot live in Java world.

Functions are first class citizens in a functional programming language. They exists on their own. You can assign them to a variable and pass them as arguments to other functions. JavaScript is one of the best example of an FP language. There are some good articles here and here that clearly describes the benefits of JavaScript as a functional language. A functional language provides very powerful feature called Closure that has quite a few advantages over traditional way of writing applications. A closure is a function or reference to a function together with a referencing environment — a table storing a reference to each of the non-local variables of that function. Closest thing that Java can provide to Closure is Lambda expressions. There is significant difference between a Closure and Lambda expression, but at least Lambda expression provides a good alternative to Closure.

In his quite sarcastic and funny blog post, Steve Yegge describes how Java world is strictly about Nouns. If you haven’t read his blog, go first read it. It’s funny, its interesting and it describe the exact reason why Java had to add Lambda expressions.

Lambda expression adds that missing link of functional programming to Java. Lambda expression let us have functions as first class citizen. Although this is not 100% correct, we will shortly see how Lambda expressions are not closures but they are as much close as we can get to closures. In languages that support first class functions, the type of the lambda expression would be a function; but in Java, the lambda expressions are represented as objects, and so they must be bound to a particular object type known as a functional interface. We will see in detail what Functional interface are.

Here is a nicely written article by Mario Fusco on Why we need Lambda Expression in Java. He explains why a modern programming language must have feature like closures.

for more details please follow the link:

http://viralpatel.net/blogs/lambda-expressions-java-tutorial/