Java Streams: Understanding the boxed() Method

What is boxed()?

The boxed() method in Java streams converts a stream of primitive types to a stream of their corresponding wrapper classes.

When to Use It

Use boxed() when you need to work with streams of objects instead of primitives, typically when:

  1. Using methods that require object streams
  2. Collecting results into collections of wrapper types

Example

IntStream intStream = IntStream.range(1, 5);
Stream<Integer> boxedStream = intStream.boxed();

Here, boxed() converts IntStream to Stream<Integer>.

Why It's Necessary

Many Stream operations and collectors work only with object streams, not primitive streams. boxed() bridges this gap, allowing you to use these operations on primitive streams.

Remember: Boxing has a performance cost, so use it judiciously.