Member-only story
Collections vs Streams in Java — Key Differences with Examples
Java is a powerful programming language known for its rich Collection Framework and functional-style Stream API. While both Collections and Streams deal with data, they are fundamentally different in purpose, behavior, and use.
Many developers — especially beginners — confuse Collections with Streams, assuming they do the same thing. However, the truth is: Collections store data, and Streams process data.
In this article, we’ll explore the key differences between Collections and Streams in Java, understand how each works, and when to use one over the other — with simple code examples and real-world use cases.
📦 What are Collections in Java?
Collections are a group of objects. Java provides a robust Collection Framework that allows us to store, access, update, and manage data efficiently.
✅ Key Features of Collections:
- Used to store and group data
- Can be modified (add, remove, update)
- Require external iteration (like loops or iterators)
- Can be traversed multiple times
- Eagerly evaluated (data is populated immediately)
Example:
import java.util.*;
public class CollectionExample {
public static void main(String[] args) {
List<String> names = new ArrayList<>()…
