Java OCP Streams and Lambda Expressions

1. Which of the following correctly creates a stream from an array?

Arrays.stream(array)

Array.stream()

New Stream(array)

Stream.of(array).stream()

2. True or False: Streams are lazy, meaning intermediate operations are executed only when a terminal operation is called.

True

False

3. What does the skip(n) operation do?

Returns first n elements

Skips first n elements and returns the rest

Returns every nth element

Removes the nth element

4. True or False: The findFirst() operation is a terminal operation.

True

False

5. True or False: The reduce() method is a terminal operation.

True

False

6. What does the peek() operation do in a stream?

Returns the first element

Performs an action on each element without modifying the stream

Removes elements from the stream

Terminates the stream

7. What is the output of the following code? List nums = Arrays.asList(1,2,3); nums.stream().map(x -> x*2).forEach(System.out::println);

1 2 3

2 4 6

Null

Compilation error

8. What does the flatMap() operation do in a stream?

Filters elements based on a predicate

Maps each element to a stream, then flattens all streams into one

Sorts stream elements in order

Removes duplicate elements

9. Which stream operation is terminal and collects stream elements into a List?

Map()

Filter()

Collect(Collectors.toList())

ForEach()

10. Which functional interface accepts a single parameter and returns a boolean?

Function

Predicate

Consumer

Supplier

11. True or False: A stream can be reused after calling a terminal operation.

True

False

12. Which of the following is a valid method reference syntax?

System.out.println

System.out::println

System.out#println

System.out->println

13. Which functional interface is used as the target type for a lambda expression with no parameters and no return value?

Supplier

Runnable

Consumer

Function

14. What is the result of stream().limit(3) on a stream of 10 elements?

Returns first 3 elements

Removes first 3 elements

Returns last 3 elements

Throws an exception

15. Which stream operation returns a boolean indicating if all elements match a predicate?

AnyMatch()

AllMatch()

NoneMatch()

FindFirst()

16. True or False: Lambda expressions can access non-final local variables.

True

False

17. What does the sorted() operation do without parameters?

Sorts in reverse order

Sorts in natural order

Removes duplicate elements

Throws an exception

18. Which method creates a stream of primitive integers from start to end?

Stream.range(1, 10)

IntStream.range(1, 10)

Stream.of(1, 10)

Arrays.stream(1, 10)

19. Which functional interface represents a function that takes one parameter and returns a value?

Consumer

Supplier

Function

Predicate

20. What is the correct syntax for a lambda expression that takes two integers and returns their sum?

(a, b) -> a + b

Lambda (a, b): a + b

(int a, int b) => a + b

Function(a, b) { return a + b; }

Oracle Java OCP Streams and Lambda Expressions Quiz

1. Which of the following correctly creates a stream from an array?

2.

What first name or nickname would you like us to use?

2. True or False: Streams are lazy, meaning intermediate operations are executed only when a terminal operation is called.

3. What does the skip(n) operation do?

4. True or False: The findFirst() operation is a terminal operation.

5. True or False: The reduce() method is a terminal operation.

6. What does the peek() operation do in a stream?

7. What is the output of the following code? List nums = Arrays.asList(1,2,3); nums.stream().map(x -> x*2).forEach(System.out::println);

8. What does the flatMap() operation do in a stream?

9. Which stream operation is terminal and collects stream elements into a List?

10. Which functional interface accepts a single parameter and returns a boolean?

11. True or False: A stream can be reused after calling a terminal operation.

12. Which of the following is a valid method reference syntax?

13. Which functional interface is used as the target type for a lambda expression with no parameters and no return value?

14. What is the result of stream().limit(3) on a stream of 10 elements?

15. Which stream operation returns a boolean indicating if all elements match a predicate?

16. True or False: Lambda expressions can access non-final local variables.

17. What does the sorted() operation do without parameters?

18. Which method creates a stream of primitive integers from start to end?

19. Which functional interface represents a function that takes one parameter and returns a value?

20. What is the correct syntax for a lambda expression that takes two integers and returns their sum?