Java Stream collect() Method with Examples

The collect() method in Java is a part of the java.util.stream.Stream interface. In this guide, we will learn how to use collect() method in Java with practical examples and real-world use cases to better understand its functionality.

Learn Java from scratch: Learn Java Programming.

Complete Java Reference: Java API Documentation.

Table of Contents

1. Introduction
2. collect() Method Syntax
3. Understanding collect()
4. Examples
5. Real-World Use Case
6. Conclusion

Introduction

The Stream.collect() method in Java gathers elements from a stream into collections like List or Set. It’s often the final step in stream processing.

Commonly, collect() is used with Collectors.toList() or Collectors.toSet() to convert a stream into a List or Set for easier data handling.

Additionally, collect() can be customized to gather elements into more complex structures like Map, providing flexibility in how stream data is accumulated.

collect() Method Syntax

There are two main overloads of the collect() method:

1. Using a Collector:

• <R, A> R collect(Collector<? super T, A, R> collector)

1. Using a supplier…