What are the differences between Java Streams API and Collections?

What are the main differences between Java Streams API and Collections?

Java Streams API is designed for processing sequences of elements, allowing for functional-style operations, while Collections are data structures that store elements. Streams are not data structures themselves; they are views of data that can be processed in a pipeline.

Can you give me an example of how to use Streams?

Sure! For example, if you have a list of integers and you want to filter out even numbers and square the remaining ones, you can do it like this:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
List<Integer> result = numbers.stream()
                               .filter(n -> n % 2 != 0)
                               .map(n -> n * n)
                               .collect(Collectors.toList());

What are the performance implications of using Streams?

Streams can be more efficient for large data sets because they allow for lazy evaluation and parallel processing. However, for small collections, the overhead of creating a stream may outweigh the benefits.

When should I use Collections instead of Streams?

Use Collections when you need to store and manipulate data directly, especially for small datasets or when you need random access. Streams are better for complex data processing tasks.