Please remember that when defining a stream we just declare the steps to follow in our pipeline of operations, they won’t get executed until we call our terminal operation. We should see Java Streams as a series of connected pipes, where in each pipe our data gets processed differently this concept is very similar to UNIX pipes! Java Streams are sequential by default, but they can be very easily parallelised. Once we call a terminal operation, a new stream would have to be generated in order to apply the same series of java streams operations. This basically means that until we call a terminal operation, our stream won’t be doing anything, we will just have declared what our pipeline will be doing. Streams are written specifying what has to be done, but not how. Let’s go into a bit more of detail briefly! Characteristics of a streamĪs it was mentioned in my last article, streams have these main characteristics: Streams are built around its main interface, the Stream interface, which was released in JDK 8. In this case the behaviour what we’re applying to each element is the one specified in our “ decorateElement” method, which will supposedly be creating a new “ enhanced” or “ decorated” element based on the existing element. map(element -> decorateElement(element)) What are Java Streams? Java Streams are basically a pipeline of aggregate operations that can be applied to process a sequence of elements.Īn aggregate operation is a higher-order function that receives a behaviour in a form of a function or lambda, and that behaviour is what gets applied to our sequence.įor example, if we define the following stream: collection.stream() Our goal is to make of this article a kind of java streams cheat sheet, but let’s start by having a brief introduction to Java Streams first! What are streams in Java You can now say good-bye to error-prone code, full of boilerplate code and clutter that was making our lives as developers much more complicated. You’ll be able to see how much easier and efficient is processing sequences of elements with streams compared to the “ old way” of doing things and how nice is to write code using fluent interfaces. This can be something very important when working with streams if our performance is going to be impacted. After having had a deep introduction to functional programming in our last article “ A new Java functional style“, we think it’s now time to look at Java Streams more in depth and understand how they work internally.
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