Question

我在程序中实现compareto和clone方法时遇到一些麻烦，我得到一个错误：“Car不是抽象的，并且不会覆盖java.lang中的抽象方法compareTo（java.lang.Object）。可比”。任何帮助表示赞赏：）

这是我到目前为止所做的：



import java.util.*;
public class Car implements Comparable, Cloneable
{

private String model;
private String color;
private int year;
private int vin_number;
private double price;



public Car(){}

public Car(String model, String color, int year, int vin_number, double price)
{
this.model = model;
this.color = color;
this.year = year;
this.vin_number = vin_number;
this.price = price;
}

public Object clone() { // shallow copy 
try
{
return super.clone();
} 
catch (CloneNotSupportedException e)
{ 
return null; 
}

}


public String getModel(){return model;} 
public String getColor(){return color;}
public int getYear(){return year;}
public int getVinNumber(){return vin_number;}
public double getPrice(){return price;}


public void setModel(String newModel){model = newModel;} 
public void setColor(String newColor){color = newColor;}
public void setYear(int newYear){year = newYear;}
public void setVinNumber(int newVinNumber){vin_number = newVinNumber;}
public void setPrice(double newPrice){price = newPrice;}

public String toString()
{
return "Model: " + model + " Color: " + color + " Year: " + year + " Vin Number: " + vin_number + " Price: " + price;
}


public int compareTo(Car o)
    {

if(this.getModel().compareTo(car.getModel())) //gives 1
return 1;

if(car.getModel().compareTo(this.getModel())) //gives -1 
return -1;

else
{
return 0; 
} 

   }

public static void main(String [] args)
{

}


}

import java.util.*; public class Car implements Comparable, Cloneable { private String model; private String color; private int year; private int vin_number; private double price; public Car(){} public Car(String model, String color, int year, int vin_number, double price) { this.model = model; this.color = color; this.year = year; this.vin_number = vin_number; this.price = price; } public Object clone() { // shallow copy try { return super.clone(); } catch (CloneNotSupportedException e) { return null; } } public String getModel(){return model;} public String getColor(){return color;} public int getYear(){return year;} public int getVinNumber(){return vin_number;} public double getPrice(){return price;} public void setModel(String newModel){model = newModel;} public void setColor(String newColor){color = newColor;} public void setYear(int newYear){year = newYear;} public void setVinNumber(int newVinNumber){vin_number = newVinNumber;} public void setPrice(double newPrice){price = newPrice;} public String toString() { return "Model: " + model + " Color: " + color + " Year: " + year + " Vin Number: " + vin_number + " Price: " + price; } public int compareTo(Car o) { if(this.getModel().compareTo(car.getModel())) //gives 1 return 1; if(car.getModel().compareTo(this.getModel())) //gives -1 return -1; else { return 0; } } public static void main(String [] args) { } }

Answer 1

您必须在实施可比较时指定要比较的类型：

class Car implements Comparable<Car>, Cloneable

原始类型将使用Object。您使用的是原始类型，因此，compareTo必须将Object声明为参数，而不是Car。

要解决此错误，请将implements Comparable更改为implements Comparable<Car>

使用compareto和clone方法有点麻烦

1 个答案: