change one Array list item order relative to another

Question

Ive got 2 Array lists

 ArrayList<String> passengerNames= new ArrayList<String>();//stores passenger names
ArrayList<String> seatNumber= new ArrayList<String>();//stores the seat passenger booked 1  seat=1passenger
    passengerNames.add("Ram");
    passengerNames.add("Shyam");
    passengerNames.add("CPS");
    passengerNames.add("John");
    passengerNames.add("Steve");

    seatNumber.add(1);
    seatNumber.add(84);
    seatNumber.add(19);
    seatNumber.add(99);
    seatNumber.add(78);

so the passengerNames array will be [Ram, Shyam, CPS, John, Steve] and seatNumber array will be [1, 84, 19, 99, 78] I want to sort the seatNumber array in accending order but I want to change the passengerNames list with it as in when seatNumber is in accending order like [1,19,78,84,99] the passengerNames array should be sorted like [Ram,CPS,Steve,Shyam,Jhon]

[Mod] - Please edit your question for a clearer more specific one, if needed please add relevant code samples — Aviram Fireberger
– Aviram Fireberger, Commented Apr 6, 2020 at 10:17

VILLAIN bryan · Accepted Answer · 2020-04-06 09:48:02Z

I would suggest encapsulating your data in a new Passenger object and creating a single ArrayList of type Passenger - this should keep things tidy and flexible.

public class Passenger {
    private String name;
    private int seatNumber;

    public Passenger(String name, int seatNumber) {
        this.name = name;
        this.seatNumber = seatNumber;
    }
}

... and for creating the Passenger ArrayList

List<Passenger> passengers = new ArrayList<Passenger>(); // build Passenger ArrayList
passengers.add(new Passenger("Ram", 1)); // create new Passenger
passengers.add(new Passenger("Shyam", 84)); // etc...

In regards to sorting the List in ascending order, a clean approach is to implement Comparable in the Passenger class, and define the behavior in the compareTo(Passenger p) method. Once that is defined to your liking, the sort can be called via Collections.sort(passengers);

Ricardo · Accepted Answer · 2020-04-06 11:09:42Z

1

Instead of having two arrays of information that belong to a single entity, create an Object Passenger in which you assign the name and seat number.

public class Passenger {

    private String name;
    private int seatNumber;

    public Passenger(String name, int seatNumber){
        this.name = name;
        this.seatNumber = seatNumber;
    }
    // setters and getters
}

Now just create your array of passengers

ArrayList<Passenger> passengers = new ArrayList<Passenger>();
passengers.add(new Passenger("Ram", 1));

Then use a sorting method by Object attribute.

Arrays.sort(passengers, Comparator.comparing(Passenger::getSeatNumber));

edited Apr 6, 2020 at 11:09

answered Apr 6, 2020 at 9:41

Ricardo

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Comments

robertobatts · Accepted Answer · 2020-04-06 09:44:40Z

0

Looks like it would be more appropriate to use a SortedMap

SortedMap<Integer, String> map = new TreeMap<>();
map.put(1, "Ram");
map.put(84, "Shyam");
map.put(19, "CPS");
map.put(99, "John");
map.put(78, "Steve");

You don't need to pass a Comparator in the constructor in your case, because you need the keys to be in ascendent order, that is their natural order. The cool thing is that they will be already sorted without doing anything, they will sort automatically as you add them

answered Apr 6, 2020 at 9:44

robertobatts

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