Multi-stream: a custom Spliterator merges two sorted feeds lazily

Stream.concat then sorted() buffers both feeds before emitting anything. A Spliterator that advances whichever side is behind emits the first element immediately and never holds more than one row per feed.

• Multi-stream: a record with a mutable component is a broken Map key
• Multi-stream: an unmodifiable view is not a snapshot of the feed
• Multi-stream: toMap's merge function runs only on a collision
• Multi-stream: nothing runs until the terminal operation
• Multi-stream: indexing the other side costs memory a sorted merge does not
• Multi-stream: UNORDERED is a promise you make, not one you receive

---

Run this yourself in the Online Java Compiler, spin up a live REST API in the API Sandbox, or practise with Java interview questions.

Published 2026-09-20

© Java Coding Hub · About · Contact · Privacy · Terms