Java stream filter specified variable, delete it and delete next 3 variables in row

Is it possible to find in stream specified variable and delete the next 3 iterated objects?

List<Double> hoursList = Arrays.asList(8.00,8.15,8.30, 8.45, 9.00,9.15, 9.30, 9.45,10.00,
            10.15,10.30,10.45,11.00);

Double visitTime = hoursList.get(4);
int n = 3;

List<Double> hours = hoursList.stream().filter(x -> !x.equals(visitTime)).collect(Collectors.toList());

this code just delete 1 object 9.00 from List it's possible to delete the next 3 objects in the row?

Expected output:

[8.00,8.15,8.30, 8.45,10.00,10.15,10.30,10.45,11.00]

As I mentioned in my comment in the original question, if you want to delete items from the List, make sure you instantiate it as new ArrayList<>(Arrays.asList()) or new ArrayList<>(List.of()) instead of Arrays.asList(). Arrays.asList() returns a fixed size wrapper around an array and is directly backed by the array. Otherwise you will get an UnsupportedOperationException.

Having said that, I would use subList for that job, it is much more simple:

hoursList.subList(4, 4 + 3 + 1).clear();

If you prefer a method that accepts parameters for more flexibility (and checks for potential index out of bounds):

public List<Double> removeHours(List<Double> hours, double hour, int nextHours) {

    int startIndex = hours.indexOf(hour);

    int finalIndex = Math.min(startIndex + nextHours + 1, hours.size());

    hours.subList(startIndex, finalIndex).clear();

    return hours;
}

Then you can do:

List<Double> hoursRemoved = removeHours(hoursList, 9.0, 3);   
System.out.println(hoursRemoved);

Output

[8.0, 8.15, 8.3, 8.45, 10.0, 10.15, 10.3, 10.45, 11.0]

You can use concatenation of two streams. Using takeWhile, dropWhile and skip, then concat two streams together, will return desired result:

    List<Double> hours = Stream.concat(
            hoursList.stream()
                    .takeWhile(e -> !e.equals(visitTime)),
            hoursList.stream()
                    .dropWhile(e -> !e.equals(visitTime))
                    .skip(3)
    ).collect(Collectors.toList());

If the elements are times, handle them as times, not as double numbers. The LocaTime class of java.time, the modern Java date and time API, is what you need.

	List<LocalTime> hoursList = Stream.iterate(LocalTime.of(8, 0), t -> t.plusMinutes(15))
			.limit(13)
			.collect(Collectors.toList());
	System.out.println(hoursList);
	
	LocalTime startTime = LocalTime.of(8, 45);
	LocalTime endTime = startTime.plusHours(1);
	List<LocalTime> hours = new ArrayList<>(hoursList);
	hours.removeIf(t -> ! t.isBefore(startTime) && t.isBefore(endTime));

	System.out.println(hours);

Output:

> [08:00, 08:15, 08:30, 08:45, 09:00, 09:15, 09:30, 09:45, 10:00, 10:15, 10:30, 10:45, 11:00]
> [08:00, 08:15, 08:30, 09:45, 10:00, 10:15, 10:30, 10:45, 11:00]

I agree with Harshal Parekh that it’s more readable and simpler to use removeIf() than a stream operation. Both options are possible. For removeIf() to work we need to make sure that we have got a modifiable list. Copying into a new ArrayList ensures this.

Link: Oracle tutorial: Date Time explaining how to use java.time.