Question

嘿，我想通过飞机环绕所有乘客并将它们添加到计数中以显示所有飞机的所有乘客。但我得到一个错误：无法迭代数组或实例。

以下是方法：

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

平面

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

passengerNumber是int。您需要迭代Iterable，例如ArrayList：

for (Plane plane: myPlaneList) {
  passengers += plane.getPassengerNumber();
}

Answer 2

您正在尝试迭代Plane对象，但您的集合只是一个int。你需要一组Plane对象

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

Answer 3

您正在尝试迭代int，您需要迭代java.util.Iterable

您发布的代码不包含回答此问题所需的信息。

您向我们展示了课程Plane，但为了拥有多个平面，您可能在代码中的其他位置有List<Plane>或Plane[]。这是一个可行的例子：

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;
  }
}

无法通过循环运行getAllPassengers

3 个答案: