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飛行機を昇順と降順で並べ替えようとしています。飛行機のハッシュマップがあり、それらを比較して、マップをtimeLimitBeforeLandで並べ替えることにより、次の飛行機の期限と最後の飛行機の期限を取得できるようにします。私は次のようなcompareToメソッドを作成しました：

//---------------------------------------------------------------------------------------
//  CompareTo() used with the Comparable implementation.
//---------------------------------------------------------------------------------------
        public int compareTo(Object arg0) 
        {
            if((arg0 != null) && (arg0 instanceof Plane))
            {
            Plane p = (Plane) arg0;
            return (int)Math.ceil(this.timeLimitBeforeLand - p.getLimitBeforeLand());
            }
            return 0;
        }

CompareToにはtimeLimitBeforeLandがかかります：

// ---------------------------------------------------------------------------------------
//      Name:        getTimeLimitBeforeLand.
//      Description: Get the time before every plane is going to land.
//---------------------------------------------------------------------------------------
        public double getTimeLimitBeforeLand()
        {
        double fuelConsumption;
        double timeLimitBeforeLand = 0;

        for (TreeMap<String, Plane> theEntry : airlineMap.values()) {
        for (Plane aPlane : theEntry.values()) {
        if (aPlane.getPlaneType() == aPlane.getPlaneType().AIRBUS) {
        System.out.println(" ");
        System.out.println(aPlane);
        fuelConsumption = 2;
        timeLimitBeforeLand = (double) (aPlane.getFuelRemaining() / fuelConsumption);
        System.out.println(timeLimitBeforeLand + " minutes to land.");
        System.out.println(" ");
        } else if (aPlane.getPlaneType() == aPlane.getPlaneType().CORPORATE) {
        System.out.println(" ");
        System.out.println(aPlane);
        fuelConsumption = 3;
        timeLimitBeforeLand = (aPlane.getFuelRemaining() / fuelConsumption);
        System.out.println(timeLimitBeforeLand + " minutes to land.");
        System.out.println(" ");
        } else if (aPlane.getPlaneType() == aPlane.getPlaneType().PRIVATE) {
        System.out.println(" ");
        System.out.println(aPlane);
        fuelConsumption = 4;
        timeLimitBeforeLand = (double) (aPlane.getFuelRemaining() / fuelConsumption);
        System.out.println(timeLimitBeforeLand + " minutes to land.");
        System.out.println(" ");
        }
        }
        }
        return timeLimitBeforeLand;
        }

mainAppでのこれまでの私の試み：

TreeMap<String, PlaneStore> map = new TreeMap<String, PlaneStore>();

        ArrayList<Plane> copyList = new ArrayList<Plane>(map.);

        Plane comp = new Plane();

        Collections.sort(copyList, plane);

平面クラス：

//---------------------------------------------------------------------------------------
//  Name:           Imports. 
//  Description:    To allow the use of different Java classes.
//---------------------------------------------------------------------------------------
import java.io.Serializable;
//---------------------------------------------------------------------------------------
//Name:         Class declaration. 
//---------------------------------------------------------------------------------------
public class Plane implements Comparable, Serializable
{   
//---------------------------------------------------------------------------------------
//  Variable declarations.
//---------------------------------------------------------------------------------------
    private String flightNumber;
    public String airlineName;
    private double fuelRemaining;
    private int overdue;
    private int passengerNumber;
//---------------------------------------------------------------------------------------
//  Enum declaration.
//---------------------------------------------------------------------------------------
    private AIRPLANETYPE planeType;
    private boolean isLanded = false;
    public double timeLimitBeforeLand;
//---------------------------------------------------------------------------------------
//  Enum Constuctor.
//---------------------------------------------------------------------------------------
    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;
        }
    }
//---------------------------------------------------------------------------------------
//  Constructor.
//---------------------------------------------------------------------------------------
    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;
    }
//---------------------------------------------------------------------------------------
//  Getters and Setters.
//---------------------------------------------------------------------------------------
    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 double getLimitBeforeLand() 
    {
        return timeLimitBeforeLand;
    }

public void setTimeLimitBeforeLand(double timeLimitBeforeLand) 
{
this.timeLimitBeforeLand = timeLimitBeforeLand;
}

//---------------------------------------------------------------------------------------
//  CompareTo() used with the Comparable implementation.
//---------------------------------------------------------------------------------------
    public int compareTo(Object arg0) 
    {
        if((arg0 != null) && (arg0 instanceof Plane))
        {
        Plane p = (Plane) arg0;
        return (int)Math.ceil(this.timeLimitBeforeLand - p.getLimitBeforeLand());
        }
        return 0;
    }
//---------------------------------------------------------------------------------------
//  toString().
//---------------------------------------------------------------------------------------
    public String toString() 
    {
        return "Plane: flightNumber=" + flightNumber + "."
                + " airlineName=" + airlineName + "."
                + " fuelRemaining=" + fuelRemaining + " litres."
                + " overdue=" + overdue + " minutes."
                + " passengerNumber="+ passengerNumber + "."
                + " airplaneType=" + planeType +
                "hasLanded=" + isLanded+ ".\n";
    }
}
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1 に答える 1

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の 2 番目の引数は、ではなくComparatorCollections.sort用です。Comparator について言及していないので、(Plane オブジェクトの compareTo メソッドによって定義された) 自然な順序を使用でき、PlaneCollections.sort

編集:そのコードを除外していない限り、Plane インスタンスを作成しておらず、ここで空のコレクションを使用しています...

   TreeMap<String, PlaneStore> map = new TreeMap<String, PlaneStore>();
   ArrayList<Plane> copyList = new ArrayList<Plane>(map.);

そして、PlaneStores で並べ替えるのでPlane、各 PlaneStore のすべての を取得し、copyList並べ替える前にそれらを追加する必要があります。

各コレクションをもう少し調査して、ニーズに最適なコレクションを決定することを検討します.

于 2012-12-14T18:52:28.457 に答える