Collectors is a final class that extends Object class. It provides reduction operations, such as accumulating elements into collections, summarizing elements according to various criteria, etc. Java Collectors class provides various methods to deal with elements.

What is collector programming?

A Collector is specified by four functions that work together to accumulate entries into a mutable result container, and optionally perform a final transform on the result. They are: creation of a new result container ( supplier() ) incorporating a new data element into a result container ( accumulator() )

What does collect () do in Java?

collect() is one of the Java 8’s Stream API’s terminal methods. It allows us to perform mutable fold operations (repackaging elements to some data structures and applying some additional logic, concatenating them, etc.) on data elements held in a Stream instance.