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Java Streams & Functional Programming – Java interview questions

Java Streams & Functional Programming interview questions for placements and exams.

Subject: JavaDifficulty: Mixed15 questions in this set

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Java – Java Streams & Functional Programming questions (15)

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1. What does Collectors.groupingBy do by default?

Difficulty: MediumType: MCQTopic: Collectors

Default `groupingBy(classifier)` uses a `HashMap<K, List<T>>`. Sorting or concurrent maps require additional downstream or mapFactory arguments.

2. Which is TRUE about lambdas compared to anonymous inner classes?

Difficulty: MediumType: MCQTopic: Lambdas

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Java Streams & Functional Programming – Java interview questions

Set overview

Java – Java Streams & Functional Programming questions (15)

1. What does Collectors.groupingBy do by default?

2. Which is TRUE about lambdas compared to anonymous inner classes?

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3. Which method reference form refers to an instance method of a particular object?

4. A Stream pipeline is composed of:

5. Which pair correctly classifies operations?

6. When should you use flatMap instead of map?

7. Which operation is stateful and may require examining the whole stream?

8. Which is a safe guideline for using parallel streams?

9. When should you prefer collect over reduce?

10. List two good practices and two anti-patterns when using Optional in Java.

11. Why use IntStream/LongStream/DoubleStream?

12. Why are side effects inside Stream intermediate operations discouraged, and what should you use instead?

13. What happens if you try to run two terminal operations on the same Stream instance?

14. What makes an interface a functional interface in Java?

15. Which statement about encounter order is correct?

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Java Streams & Functional Programming – Java interview questions

Set overview

1. What does Collectors.groupingBy do by default?

2. Which is TRUE about lambdas compared to anonymous inner classes?

Continue your preparation

3. Which method reference form refers to an instance method of a particular object?

4. A Stream pipeline is composed of:

5. Which pair correctly classifies operations?

6. When should you use flatMap instead of map?

7. Which operation is stateful and may require examining the whole stream?

8. Which is a safe guideline for using parallel streams?

9. When should you prefer collect over reduce?

10. List two good practices and two anti-patterns when using Optional in Java.

11. Why use IntStream/LongStream/DoubleStream?

12. Why are side effects inside Stream intermediate operations discouraged, and what should you use instead?

13. What happens if you try to run two terminal operations on the same Stream instance?

14. What makes an interface a functional interface in Java?

15. Which statement about encounter order is correct?

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