List<List<String>> listOfLists = Arrays.asList(
            Arrays.asList("Reflection", "Collection", "Stream"),
            Arrays.asList("Structure", "State", "Flow"),
            Arrays.asList("Sorting", "Mapping", "Reduction", "Stream")
        );
Stream<String> str= list.stream();  ->provides stream of values that can be used only once for operations related to stream like .map(), .filter(), .sorted() and then it is deleted from the memory.

List<String> result = list.stream()
			.flatMap(List::stream)                // Flatten the list of lists into a single stream
            .filter(s -> s.startsWith("S"))      // Filter elements starting with "S"
            .map(String::toUpperCase)            // Transform each element to uppercase
            .distinct()                          // Remove duplicate elements
            .sorted()                            // Sort elements
            .peek(s -> intermediateResults.add(s)) // Perform an action (add to set) on each element
            .collect(Collectors.toList());
			
			// Print the final result
        System.out.println("Final Result:");
        result.forEach(System.out::println);
		
	Output	==>
	Final Result:
	SORTING
	STATE
	STREAM
	STRUCTURE
	
	List<Integer> nums= Arrays.asList(2,3,4,5,6);
	int result= nums.stream()
							  .map(n -> n*2)
							  .reduce(0, (a,b) -> a+b);            //.reduce() method is used to calculate the sum of stream after processing
	System.out.println(result);
	Output
	40