In this tutorial you’ll see how to convert a Stream to Set using collector method and utility methods like toSet() and toCollection() of Collectors class in Java Stream API. 1. A simple example to collect Stream elements into a HashSet. import java.util.Set; import java.util.stream.Collectors; import java.util.stream.Stream; public class StreamToSet {…
In this tutorial you’ll see how to convert a Stream to list using collector method and utility methods like toList() and toCollection() of Collectors class in Java Stream API. 1. A simple example to collect Stream elements into an ArrayList. import java.util.List; import java.util.stream.Collectors; import java.util.stream.Stream; public class StreamToList {…
In this tutorial we’ll see what options are there to get the last element of the stream using the Java Stream API. 1. Using reduce() method reduce method in the Java Stream API is used to perform a reduction on the elements of the stream so that the stream is…
When you use map operations in Java Stream resulting stream is obtained by applying the given function to all the elements of this stream. Java Stream API also provides a flatMap() method that apart from applying the given function to all the elements of this stream, flattens the resulting elements…
In this post we’ll see examples of map() function in Java Stream API that is used to apply some transformation to the elements in a stream. When you use a map operation a new stream is returned consisting of the resultant elements after applying the given function to all the…
In this tutorial we’ll see how to use Collectors.teeing() method which is added in Java 12 to the Collectors class in the Java Stream API. Collectors.teeing() method The teeing() method let you create a composite of two Collectors and there is also a third argument; a merging function. Every element…
In this tutorial we’ll see examples of Collectors.partitioningBy() method which is part of the Collectors class in the Java Stream API. Collectors.partitioningBy() method partitions the input elements according to a passed Predicate (which defines the condition for partitioning), and organizes them into a Map<Boolean, List> with values assigned to two…
In this tutorial we’ll see some examples of Collectors.groupingBy() method in Java Stream API. Collectors.groupingBy() method works similarly to “group by” statement in SQL which groups the elements as per the specified columns. This method also groups the elements according to the passed property and returns grouped result as a…
In this tutorial we’ll see how to use Collectors.joining() method to concatenate the input elements into a String. It is a handy utility method provided by the Collectors class in Java Stream API to quickly convert array elements or elements in a collection to String. There are three overloaded Collectors.joining()…
When using Java streams, most of the time you will have a Collection as a source for the stream but you can also do the opposite i.e. obtain a Collection from a Stream. To do that you can use collect() method in the Java Stream API. Here note that collect()…
