All You Need to Know about Java 8 Streams API

Java 8 Streams API

Going through lots of changes and becoming more concurrent, Java 8 has developed a Streams API to ensure full support of multiple operations concerning data processing. Due to modern-day development tendencies when multicore CPUs are becoming more common and when you as the developer should have a chance to focus more on data and the operations that need the data, you should definitely learn more about the Streams API.

Professionals know that parallel processing is all about breaking big tasks into smaller ones, processing them concurrently and then combining the results together. Java 8 Streams API is providing the similar process for Java Collections – the main idea here is actually converting Collections into Streams and working with its elements. And once everything is processed you gather the result back into the Collection.

Collections or Streams?

The classic and well-known Collections are in-memory structures that hold data elements within them. Each element is computed before it becomes the part of the structure. Streams, on the other hand, consists of the fixed data structures that are computed on demand.

The Streams is a sequence of elements, and it supports various types of operations to perform computations.

Streams: a closer look at the details

Java.util.streams package defines the Stream interface. Operations in the Stream are either intermediate or terminal. All the intermediate operations return to Streams so that you can combine a group of them without the use of a semicolon. Terminal operations return void or non-streaming results.

Streams may be created from various data sources, especially Collections. List and Set collections support new methods of the stream and parallelStream. Parallel streams share a common ForkJoinPool available through static ForkJoinPool.commonPool method. The size of the primary thread pool uses five strands – depending on the number of available physical processor cores.

But keep in mind – it is not recommended to use a parallel stream for extended operations (retrieving data from the database, network connections). All parallel stream work with a single pool of fork/join and such long operation may stop all parallel streams in the JVM due to the lack of available threads in a pool.

There are plenty of functions and operations you can perform within the stream. For example, having a collection of class ‘People’ with parameters ‘name,’ ‘age,’ ‘sex,’ and ‘type’ Arrays.asList you can find the average age of the men, or find some potentially-bodied people in the sample.

The Bottom Line

Being a huge concept to Java 8, Streams are still gaining the popularity among professionals due to various reasons. But if you are about to implement it into your work, you should know more about the way the stream can be built and operated.