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Explanation:
Explanation:
Answer:
The Stream API introduced in Java 8 revolutionized the way we handle collections and perform operations on them. It provides a powerful and concise way to manipulate data using functional programming principles.
In this blog post, we present a Java 8 Stream API Quiz consisting of multiple-choice questions (MCQ) to assess your understanding of the Stream API concepts, including stream creation, operations, terminal operations, and functional interfaces. Let's dive into the quiz and test your knowledge of the Java 8 Stream API!
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1. What is the Stream API in Java?
a) A feature for handling files in Java
b) A way to process sequences of elements in a functional style
c) A method for sorting arrays
d) An interface for input/output operations
Answer:
b) A way to process sequences of elements in a functional style
Explanation:
The Stream API in Java is a feature that allows for processing sequences of elements in a functional style. It was introduced in Java 8.
2. Which Java version introduced the Stream API?
a) Java 7
b) Java 8
c) Java 9
d) Java 10
Answer:
b) Java 8
Explanation:
The Stream API was introduced in Java 8 as part of the java.util.stream package.
3. What is the main purpose of the Stream API?
a) To perform I/O operations
b) To handle exceptions
c) To process collections of data in a functional style
d) To create multi-threaded applications
Answer:
c) To process collections of data in a functional style
Explanation:
The main purpose of the Stream API is to process collections of data in a functional style, enabling operations like filtering, mapping, and reducing.
4. Which of the following is NOT a characteristic of streams in Java?
a) Streams are immutable
b) Streams can be parallel
c) Streams store elements
d) Streams can be infinite
Answer:
c) Streams store elements
Explanation:
Streams do not store elements; they process data in a pipeline. Streams are immutable, can be parallel, and can be infinite.
5. Which method is used to create a stream from a collection in Java?
a) stream()
b) createStream()
c) asStream()
d) toStream()
Answer:
a) stream()
Explanation:
The stream() method is used to create a stream from a collection, such as a List or Set.
6. What is the difference between a stream() and a parallelStream() in Java?
a) stream() is faster than parallelStream()
b) parallelStream() processes elements in parallel
c) stream() uses more memory
d) parallelStream() is only for arrays
Answer:
b) parallelStream() processes elements in parallel
Explanation:
The parallelStream() method processes elements in parallel, potentially improving performance on multi-core processors.
7. Which of the following is a terminal operation in the Stream API?
a) filter()
b) map()
c) reduce()
d) sorted()
Answer:
c) reduce()
Explanation:
The reduce() method is a terminal operation that reduces the elements of a stream into a single value using a given accumulator function.
8. Which method is used to filter elements of a stream?
a) filter()
b) map()
c) collect()
d) flatMap()
Answer:
a) filter()
Explanation:
The filter() method is used to filter elements of a stream based on a given predicate.
9. What does the map() method do in a stream?
a) It maps each element to a collection
b) It transforms each element in the stream
c) It groups elements by a common key
d) It sorts the elements in the stream
Answer:
b) It transforms each element in the stream
Explanation:
The map() method transforms each element in the stream using a given function, producing a new stream of transformed elements.
10. Which method is used to collect the results of a stream operation into a List?
a) toList()
b) collect()
c) gather()
d) accumulate()
Answer:
b) collect()
Explanation:
The collect() method is used to collect the results of a stream operation into a List, Set, or other collection types.
11. What is the purpose of the forEach() method in the Stream API?
a) To count the elements in the stream
b) To iterate over each element in the stream and perform an action
c) To remove duplicates from the stream
d) To sort the elements in the stream
Answer:
b) To iterate over each element in the stream and perform an action
Explanation:
The forEach() method is a terminal operation that iterates over each element in the stream and performs the specified action.
12. Which method is used to find the first element in a stream?
a) findFirst()
b) firstElement()
c) getFirst()
d) find()
Answer:
a) findFirst()
Explanation:
The findFirst() method is used to find the first element in a stream and returns an Optional containing the element if it exists.
13. What does the distinct() method do in the Stream API?
a) It filters out null elements
b) It removes duplicate elements from the stream
c) It sorts the elements in the stream
d) It transforms the elements in the stream
Answer:
b) It removes duplicate elements from the stream
Explanation:
The distinct() method is used to remove duplicate elements from the stream, ensuring that each element appears only once.
14. Which of the following is a short-circuiting terminal operation in the Stream API?
a) forEach()
b) map()
c) filter()
d) anyMatch()
Answer:
d) anyMatch()
Explanation:
The anyMatch() method is a short-circuiting terminal operation that returns true if any element in the stream matches the given predicate.
15. Which method is used to convert a stream to an array?
a) toArray()
b) collect()
c) streamArray()
d) asArray()
Answer:
a) toArray()
Explanation:
The toArray() method is used to convert the elements of a stream into an array.
16. What is the purpose of the flatMap() method in the Stream API?
a) To flatten a stream of streams into a single stream
b) To map each element to its length
c) To concatenate two streams
d) To filter elements based on a predicate
Answer:
a) To flatten a stream of streams into a single stream
Explanation:
The flatMap() method is used to flatten a stream of streams into a single stream by applying a function that maps each element to a stream and then concatenating all the resulting streams.
17. Which method is used to sort elements in a stream?
a) sort()
b) order()
c) sorted()
d) arrange()
Answer:
c) sorted()
Explanation:
The sorted() method is used to sort the elements in a stream either in natural order or using a custom comparator.
18. Which method can be used to check if all elements in a stream match a given predicate?
a) allMatch()
b) anyMatch()
c) noneMatch()
d) matchesAll()
Answer:
a) allMatch()
Explanation:
The allMatch() method is used to check if all elements in a stream match the given predicate.
19. What does the reduce() method do in the Stream API?
a) It reduces the size of the stream
b) It applies an accumulation function to combine elements into a single result
c) It removes elements from the stream
d) It maps elements to their reduced form
Answer:
b) It applies an accumulation function to combine elements into a single result
Explanation:
The reduce() method is used to apply an accumulation function to the elements of a stream, combining them into a single result.
20. Which method is used to skip the first few elements in a stream?
a) skip()
b) drop()
c) omit()
d) jump()
Answer:
a) skip()
Explanation:
The skip() method is used to skip the first n elements in a stream and return a stream containing the remaining elements.
21. What is the purpose of the peek() method in the Stream API?
a) To modify the elements of a stream
b) To view elements of a stream without modifying them
c) To remove elements from a stream
d) To sort the elements of a stream
Answer:
b) To view elements of a stream without modifying them
Explanation:
The peek() method is used to view elements of a stream without modifying them. It is often used for debugging purposes.
22. Which method is used to limit the number of elements in a stream?
a) limit()
b) reduce()
c) cap()
d) filter()
Answer:
a) limit()
Explanation:
The limit() method is used to limit the number of elements in a stream to the specified size.
23. Which method is used to find the maximum element in a stream?
a) max()
b) top()
c) highest()
d) peak()
Answer:
a) max()
Explanation:
The max() method is used to find the maximum element in a stream based on a given comparator.
24. What is a pipeline in the context of the Stream API?
a) A series of operations performed on a stream
b) A method to combine multiple streams
c) A way to store intermediate results in a stream
d) A function that modifies elements in a stream
Answer:
a) A series of operations performed on a stream
Explanation:
A pipeline in the context of the Stream API refers to a series of operations performed on a stream, typically consisting of a source, intermediate operations, and a terminal operation.
25. Can streams in Java be reused?
a) Yes, streams can be reused multiple times
b) No, streams cannot be reused once they are consumed
c) Yes, but only parallel streams
d) Yes, if they are collected first
Answer:
b) No, streams cannot be reused once they are consumed
Explanation:
Streams in Java cannot be reused once they are consumed. After a terminal operation is performed, the stream is considered closed and cannot be used again.
Conclusion
Congratulations on completing the Java 8 Stream API Quiz! We hope this quiz challenged your knowledge and enhanced your understanding of the Stream API concepts in Java 8. The Stream API provides powerful tools for manipulating and processing collections with concise and functional-style code.
Learn and Master Java Programming: Learn Java Programming with Examples
Learn everything about Java 8 features: Java 8 Tutorial and Examples
Check out 100+ quiz questions: 100+ Quiz Questions to Test Your Java, Spring Boot, Microservices, Hibernate, REST API Skills
Keep practicing and exploring more advanced Stream operations to become proficient in leveraging the Java 8 Stream API's capabilities.
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