java - 我在使用 CompareTo 时遇到问题

Question

好吧，我需要创建一个项目，其中有两个接口(interface)，并且它们都在两个不相关的类中使用。除了compareTo 方法之外，我设法使其他所有内容都能正常运行。我制作的两个类(class)是汽车和马。我想做的是将 Horse 中的 MilesGoal 与 Car 中的 MilesGoal 进行比较，然后返回 1、0 或 -1。

但是，当我尝试这样做时，我收到错误“无法取消引用 double ”

我已经在这个问题上停留了一段时间，试图找到不同的方法来处理这部分代码。我尝试在测试器类中使用compareTo而不是创建一个方法，但我得到了相同的错误，并且我需要将其创建为一个方法。

这是马类:

public class Horse implements milesInterface , kilometersInterface{
private double currentMile;
private double currentKilo;
private double milesGoal;
private double kilosGoal;
private String horseBreed;

// CONSTRUCTORS
public Horse(){
    currentMile = 0;
    currentKilo = 0;
    milesGoal = 0;
    kilosGoal = 0;
    horseBreed = "Unspecified";
}
public Horse(double cm, double ck, double mg, double kg, String hb){
    currentMile = cm;
    currentKilo = ck;
    milesGoal = mg;
    kilosGoal = kg;
    horseBreed = hb;
}

// MILE METHODS
public double remainingMiles(){ // Finds the remaining miles
    return milesGoal-currentMile;
}
public void halfMile(){ // Divides the desired goal halfway (Miles)
    milesGoal = milesGoal/2;
} 
public void setMileGoal(double newMile){ // Allows you to set a new goal
    milesGoal = newMile;
}
public double getMileGoal(){
    return milesGoal;
}

// KILOMETER METHODS
public double remainingKilos(){ // Finds the remaining Kilos
return kilosGoal-currentKilo;
}
public void halfKilo(){ // Divides the desire goal halfway (Kilos)
    kilosGoal = kilosGoal/2;
}
public void setKiloGoal(){ // Allows you to set a new goal
    kilosGoal = milesGoal*1.6;
}
public void setCurrentKilo(){ // Allows you to set the current Kilo
    currentKilo = currentMile * 1.6;
}

// UNIQUE METHODS
public double getMilesStatus(){
    return currentMile;
}
public double getKilosStatus(){
    return currentKilo;
}
public String getHorseBreed(){
    return horseBreed;
}
public void convertToKilos(){ // Converts current miles to kilometers
    double kilos = currentMile * 1.6;
    System.out.println("The current miles to kilometers is: " + kilos + "km.");
}
public void convertToMiles(){ // Converts current kilometers to miles
    double miles = currentKilo * .6;
    System.out.println("The current kilometers to miles is: " + miles + "m.");
}
public void milesPerHour(double hours){ // Calculates the mph to the goal by a time
double answer = milesGoal / hours;
System.out.println("The mph needed to reach the desination in " + hours + " hours: " + answer);
}
 public void kilosPerHour(double hours){ // Calculates the kmph to the goal by a time
double answer = kilosGoal / hours;
System.out.println("The kilometers needed to reach the desination in " + hours + " hours: " + answer);
}
public int compareTo(Object Other){

    if(milesGoal > (Horse)milesGoal.Other)
        return 1;
    if(milesGoal < (Horse)milesGoal.Other)
        return 0;
        return -1;
    }
 }

汽车类别与马类别几乎相同，我需要找到一种方法来比较它们的英里目标，看看哪一个更大。我尝试了多种方法，但似乎不起作用

这是我做的界面:

abstract interface milesInterface{
public double remainingMiles();
public void halfMile();
public void setMileGoal(double newMile);
public int compareTo(Object Other);
}
abstract interface kilometersInterface{
public double remainingKilos();
public void halfKilo();
public void setCurrentKilo();
public int compareTo(Object Other);
}

Answer 1

首先，您正在编写attribute.object。这就是失败的原因。 Other.milesGoal 是一个更好的选择。

另一个问题是选角。您正在做的是将 milesGoal.other 转换为 Horse (您想要转换 milesGoal)

你应该使用

       if (milesGoal > ((Horse) other).milesGoal)

此外，使用正确的大写(变量采用小写，类/接口(interface)采用大写)以及 setter 和 getter。

此外，您可能需要转换为接口(interface)，以便可以将这些方法与实现它的其他类一起使用

       if (milesGoal > ((MilesInterface) other).milesGoal)