One of the highlights for me of JavaOne was the technical keynote. I found especially useful the explanation by Mark Reinhold of Lambda (I finally get it!). So I have reproduced his slides here with my thoughts. (Apologies that some of my photos are slightly out of focus).
TWO key objects of Java is readability and abstraction (both allowing the portability of code and giving the JVM the opportunity to make optimisations including using parallel cores). Lambda gives both. It is also the revolutionary feature in Java 8.
Traditional Java code can be fairly verbose. This code to remove all adults from a group needs an iterator and a loop.
We can improve the layout by using Interfaces but we still end up with overly complex code.
Wouldn’t it be nice if we could rewrite it like this! The code is much clearly and more closely resembles the problem it is solving. And the JVM can optimise if possible across multiple cores.
And we can do complex comparisons easily.
Another comparison shows just come much cleaner the Lambda code is (and how much easier it is to read the code).
Try and guess what the code does from the example above and then look at the lambda implementation
Lambda also introduces this concept of streams and makes some major changes to Collections. Several of the major language changes are to preserve backwards compatibility, such as default implementations for methods (allowing retrofitting of code onto existing libraries). Lambda also avoids lots of object creation in its processing steps.
So there you have a description of Lambdas. My definition of an excellent teacher is someone who makes the most complex things seem obvious and Mark Reinhold definitely achieved that…
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Mark Stephens
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