Java Stream API Quiz

1: What does the `filter` method do in the Stream API?

a) Applies a mapping function to the elements.
b) Filters elements based on a predicate.
c) Converts the stream into an array.

2: What is the purpose of the `map` method in the Stream API?

a) Filters elements based on a predicate.
b) Applies a mapping function to the elements.
c) Converts the stream into an array.

3: What does the `flatMap` method do in the Stream API?

a) Filters elements based on a predicate.
b) Flattens a nested Optional structure.
c) Applies a mapping function to the elements.

4: What is the terminal operation used to collect elements into a Map in the Stream API?

a) toList()
b) toMap()
c) collectMap()

5: What does the `reduce` method do in the Stream API?

a) Reduces the stream to a single element.
b) Reverses the order of elements in the stream.
c) Removes elements based on a predicate.

6: In the Stream API, what is the purpose of the `forEach` method?

a) Applies a mapping function to each element.
b) Performs an action for each element in the stream.
c) Filters elements based on a predicate.

7: What is the purpose of the `distinct` method in the Stream API?

a) Removes duplicate elements from the stream.
b) Sorts the elements in ascending order.
c) Filters out null values.

8: What does the `anyMatch` method do in the Stream API?

a) Checks if all elements match a given predicate.
b) Checks if any element matches a given predicate.
c) Checks if none of the elements match a given predicate.

9: What is the purpose of the `sorted` method in the Stream API?

a) Converts the stream into a sorted array.
b) Sorts the elements in natural order.
c) Filters out null values.

10: What is the purpose of the `findFirst` method in the Stream API?

a) Finds the first element in the stream.
b) Finds the last element in the stream.
c) Finds any element in the stream.

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