Conversion of loops to Java Streams

I am writing this logic where I am assigning individual rooms to each employee, the code of which i am pasting below :

public List<EmployeeRooms> assignRoomEmployee(Request request) {
	List<Employee> allEmployeeList = getAllEmployeeList(request);
	int possibleAssigments = Math.min(request.getRooms().size(), allEmployeeList.size());   	 
	List<EmployeeRooms> finalList = new ArrayList<>();
	int i = 0;
	while(i < possibleAssigments) {	      		        		   			
	 for (int j= 0; j < allEmployeeList.size(); j++) {	        			 
		 finalList.add(createRoomEmployeeList(allEmployeeList.get(j), request.getRooms().get(i)));        			         			 
		 i++;
		 }     		
	}
	return finalList;
	
}

Now I would like to write this loop logic using a single Java streams statement but not I have been able to do so correctly, I tried this below code but it assigns each room to each employee thus creating duplicates instead of each room to individual employee:

 while(i < possibleAssigments) {	   		 
	 allEmployeeList.stream()
                    .map(emp -> createRoomEmployeeList(emp, request.getRooms().get(i)))
                    .collect(Collectors.toList());
	 i++;
 }

You can use IntStream() to loop between i and possibleAssigments then return a RoomEmployeeList for each iteration:

x -> createRoomEmployeeList(allEmployeeList.get(x), request.getRooms().get(x)))

and finally collect them.

I didn't tested but it should be something like this:

finalList = IntStream.range(i, possibleAssigments).boxed().map(
				x -> createRoomEmployeeList(allEmployeeList.get(x), request.getRooms().get(x)))
				.collect(Collectors.toList());

The assignRoomEmployee() method:

public List<EmployeeRooms> assignRoomEmployee(Request request) {
	List<Employee> allEmployeeList = getAllEmployeeList(request);
	int possibleAssigments = Math.min(request.getRooms().size(), allEmployeeList.size());
	int i = 0;
	
	List<EmployeeRooms> finalList = IntStream.range(i, possibleAssigments).boxed().map(
			x -> createRoomEmployeeList(allEmployeeList.get(x), request.getRooms().get(x)))
			.collect(Collectors.toList());

	return finalList;
}

The only mistake I see is that you don't save the result of this stream action in a variable.

This should probably be

 List<EmployeeRooms> finalList = new ArrayList<>();
 while(i < possibleAssigments) {             
     finalList.addAll(allEmployeeList.stream().map(emp -> createRoomEmployeeList(emp, request.getRooms().get(i))).collect(Collectors.toList()));
     i++;
 }

To assign room to employee

• Iterate 0 to possibleAssigments-1
• Get employee allEmployeeList.get(i) and room request.getRooms().get(i)
• create EmployeeRooms

Using Stream API you can do this way.

List<EmployeeRooms> finalList = 
    IntStream.range(0, possibleAssigments)
             .boxed()
             .map(i -> createRoomEmployeeList(allEmployeeList.get(i),
                                              request.getRooms().get(i)))
             .collect(Collectors.toList());