Java StreamsTag ArchiveSubscribe

Java Streams Stream Basics + The Java 8 Stream API Tutorial + Introduction to Java 8 Streams + Java 8 Stream findFirst() vs. findAny() + Functional Interfaces in Java 8 Stream Collectors + Guide to Java 8’s Collectors + Guide to Java 8 groupingBy Collector + New Stream Collectors in… Continue Reading java-streams

The Difference Between map() and flatMap() 1. Overview map() and flatMap() APIs stem from functional languages. In Java 8, you can find them in Optional, Stream and in CompletableFuture (although under slightly different name). Streams represent a sequence of objects, whereas optionals are classes that represent a value that can… Continue Reading java-difference-map-and-flatmap

Filtering a Stream of Optionals in Java 1. Introduction In this article, we’re going to talk about how to filter out non-empty values from a Stream of Optionals. We’ll be looking at three different approaches – two using Java 8 and one using the new support in Java 9. We… Continue Reading java-filter-stream-of-optional

Merging Streams in Java 1. Overview In this quick article, we explain different ways of merging Java Streams – which is not a very intuitive operation. 2. Using Plain Java The JDK 8 Stream class has some useful static utility methods. Let’s take a closer look at the concat() method.… Continue Reading java-merge-streams

Collect a Java Stream to an Immutable Collection 1. Introduction In this quick article, we’re going to have a look at various ways of collecting Java Streams to immutable Collections – which require a special approach because standard Collectors work only with mutable data structures. 2. Maven Dependency We are… Continue Reading java-stream-immutable-collection

Java 8 Collectors toMap 1. Introduction In this quick tutorial, we’re going to talk about the toMap() method of the Collectors class. We’ll use it to collect Streams into a Map instance. For all the examples covered in here, we’ll use a list of books as a starting point and… Continue Reading java-collectors-tomap