Remove item from Nested list Java Stream

Question

I'll appreciate some help with this please. Assuming I have

            "bookingId": 4,
            "flights": [
                {   ...
                    "flightNumber": "AUS382",
                },
                {    ...
                    "flightNumber": "ZOD498",
                }
            ]
        },

and i want to remove flights with flightNumber of ZOD498 alone, how do i go about that?

I've tried passengerBooking.removeIf(e -> e.getFlights().stream().anyMatch(flightToRemove))

where a is a predicate - Predicate<Flight> flightToRemove = e -> "ZOD498".equals(e.getFlightNumber())

That kinda works, but removes the whole flight object, so the output now becomes

"bookingId": 4,
            "flights": [
            ]
        },

Please what modification do i need to make to remove a specific flight and have a result similar to

"bookingId": 4,
            "flights": [
                {   ...
                    "flightNumber": "AUS382",
                }
                
            ]
        },

Thank You

Answer 1

Assuming you have a class PassengerBooking with a List of objects Flight , and that the passengerBooking variable represents a List of objects PassengerBooking .

You could traverse the items of your List . Then, for each PassengerBooking object retrieve the List of Flight with the corresponding getter and then invoke the removeIf method on the Collection returned.

public class Main {
    public static void main(String[] args) {
        List<PassengerBooking> passengerBooking = new ArrayList<>(List.of(
                new PassengerBooking(4, new ArrayList<>(List.of(
                        new Flight("AUS382"),
                        new Flight("ZOD498")
                )))
        ));

        System.out.println(passengerBooking);

        for (PassengerBooking passenger: passengerBooking){
            passenger.getFlights().removeIf(f -> f.getFlightNumber().equals("ZOD498"));
        }

        System.out.println(passengerBooking);
    }
}

Besides, if this is a common operation for your PassengerBooking class, you could think of implementing a custom method to remove a Flight by its id.

This is a simple assumption of your classes' implementation to test the code above.

class PassengerBooking {
    private int bookingId;
    private List<Flight> flights;

    public PassengerBooking(int bookingId, List<Flight> flights) {
        this.bookingId = bookingId;
        this.flights = flights;
    }

    public int getBookingId() {
        return bookingId;
    }

    public List<Flight> getFlights() {
        return flights;
    }

    //Custom utility method
    public void removeFlight(String flightID){
        flights.removeIf(f -> f.getFlightNumber().equals("ZOD498"));
    }

    @Override
    public String toString() {
        return String.format("%d => %s", bookingId, flights);
    }
}

class Flight {
    private String flightNumber;

    public Flight(String flightNumber) {
        this.flightNumber = flightNumber;
    }

    public String getFlightNumber() {
        return flightNumber;
    }

    @Override
    public String toString() {
        return flightNumber;
    }
}