Prepare for your Java interviews with these detailed Stream API questions and answers. Learn how to use map, filter, reduce, collect, and more—explained with real examples and professional clarity.

Ramesh Fadatare

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8 min read

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Apr 4, 2025

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Stream API is one of the most powerful features introduced in Java 8. It allows you to work with collections in a declarative, functional way by chaining operations like filtering, mapping, and reducing.

In this article, we’ll dive into the top 15 Java Stream API interview questions asked in 2025.

1️⃣ What is Java Stream API and Why is it Useful?