Question

Hey i want to loop through planes to get all passengers and add them to a count to display all passengers for all planes. But im getting an error: Cannot iterate over an array or an instance.

Here is the method:

public int getAllPassengers()
    {
        int passengers = 0;
        for(Plane plane : plane.getPassengerNumber())
        {
            passengers += plane.getPassengerNumber();
        }
        return passengers;
    }

Plane

import java.util.LinkedList;

public class Plane implements Comparable
{   
    private String flightNumber;
    public String airlineName;
    private double fuelRemaining;
    private int overdue;
    private int passengerNumber;
    private AIRPLANETYPE planeType;
    private boolean isLanded = false;

    public enum AIRPLANETYPE
    {
        AIRBUS("1"), CORPORATE("2"), PRIVATE("3");

        private String planeName;

        private AIRPLANETYPE(String planeName)
        {
            this.planeName = planeName;
        }

        public String getPlaneName()
        {
            return this.planeName;
        }
    }

    public Plane(String flightNumber, String airlineName,
           double fuelRemaining, int overdue, int passengerNumber, 
           AIRPLANETYPE planeType, boolean isLanded) 
    {
        this.flightNumber = flightNumber;
        this.airlineName = airlineName;
        this.fuelRemaining = fuelRemaining;
        this.passengerNumber = passengerNumber;
        this.overdue = overdue;
        this.planeType = planeType;
        this.isLanded = isLanded;
    }


    public Plane() 
    {

    }


    public String getAirlineName() {
        return airlineName;
    }

    public void setAirlineName(String airlineName) {
        this.airlineName = airlineName;
    }


    public void setOverdue(int overdue) {
        this.overdue = overdue;
    }

    public int getOverdue(){
        return overdue;
    }

    public String getFlightNumber() {
        return flightNumber;
    }

    public void setFlightNumber(String flightNumber) {
        this.flightNumber = flightNumber;
    }

    public double getFuelRemaining() {
        return fuelRemaining;
    }

    public void setFuelRemaining(double fuelRemaining) {
        this.fuelRemaining = fuelRemaining;
    }

    public int getPassengerNumber() {
        return passengerNumber;
    }

    public void setPassengerNumber(int passengerNumber) {
        this.passengerNumber = passengerNumber;
    }

    public AIRPLANETYPE getPlaneType() {
        return planeType;
    }

    public void setPlaneType(AIRPLANETYPE planeType) {
        this.planeType = planeType;
    }


    public boolean isLanded() {
        return isLanded;
    }


    public void setLanded(boolean isLanded) {
        this.isLanded = isLanded;
    }


    public int compareTo(Object arg0) {
        if((arg0 != null) && (arg0 instanceof Plane))
        {
            Plane p = (Plane) arg0;
            return (int)Math.ceil(this.overdue - p.getOverdue());
        }
        return 0;
    }
    public String toString() {
        return "Plane: flightNumber=" + flightNumber + "."
                + " airlineName=" + airlineName + "."
                + " fuelRemaining=" + fuelRemaining + " litres."
                + " overdue=" + overdue + " minutes."
                + " passengerNumber="+ passengerNumber + "."
                + " airplaneType=" + planeType +
                "hasLanded=" + isLanded+ ".\n";
    }
}

Answer 1

You are trying to iterate over an int, you need to iterate over an java.util.Iterable

Your posted code does not contain the information needed to answer this question.

You are showing us the class Plane, but in order to have more than one plane, you probably have a List<Plane> or a Plane[] somewhere else in the code. Here’s one example that would work:

public class Main {
  List<Plane> allPlanes; // Load in the omitted code somewhere else

  public int getAllPassengers()
  {
    int passengers = 0;
    for(Plane plane : allPlanes) // note the change
    {
        passengers += plane.getPassengerNumber();
    }
    return passengers;
  }
}