Experience Interview Question and Answer on Java Stream API

 Introduction:

Java Stream API is a powerful feature introduced in Java 8 that provides a functional programming style for processing collections of data. In this article, we will discuss some experience interview questions related to Java Stream API and provide answers to help you prepare for your next interview.

Question 1: What is the difference between a Stream and a Collection in Java?

Answer: A Collection is a data structure that holds a group of objects, whereas a Stream is a sequence of objects that can be processed in a functional style. Collections are typically used for storing and retrieving data, while Streams are used for processing and transforming data.

Question 2: What are the benefits of using Java Stream API?

Answer: Java Stream API provides several benefits, including:

Simplifies processing of large data sets

Enables parallel processing for improved performance

Provides a functional programming style for more concise and expressive code

Supports lazy evaluation, which reduces memory usage and improves performance

Question 3: What is the difference between intermediate and terminal operations in Java Stream API?

Answer: Intermediate operations are operations that transform a Stream into another Stream, while terminal operations are operations that produce a result or a side-effect. Intermediate operations include operations like filter(), map(), and sorted(), while terminal operations include operations like forEach(), collect(), and reduce().

Question 4: How do you convert a Stream to a List in Java?

Answer: To convert a Stream to a List in Java, you can use the collect() method with the Collectors.toList() method, as shown below:

List<String> list = stream.collect(Collectors.toList());

Question 5: What is lazy evaluation in Java Stream API?

Answer: Lazy evaluation is a technique used in Java Stream API that postpones the evaluation of an operation until it is actually needed. This allows for more efficient use of memory and can improve performance. Lazy evaluation is supported by intermediate operations in Stream API.

Conclusion:

Java Stream API is a powerful feature that provides a functional programming style for processing collections of data. In this article, we discussed some experience interview questions related to Java Stream API and provided answers to help you prepare for your next interview. By understanding these concepts and practicing with Java Stream API.