No.	Question

1.	Find the second highest number in a list using Streams.

2.	Count duplicate elements in a list.

3.	Find first non-repeating character in a string using streams.

4.	Group a list of objects by a field (like department or age) using Collectors.groupingBy.

5.	Find all elements that occur more than once in a list.

6.	Sort a list of custom objects using Comparator with Streams.

7.	Find the frequency of each character in a string.

8.	Remove duplicates from a list using streams.

9.	Convert a list of strings to uppercase and collect it back.

10.	Flatten a list of lists using flatMap.