overriding 的效果是暂时的还是永久的？

Question

我在我的一个程序中编写了这些代码行，用于改变 class 的两个实例之间的相等性比较，从它们的引用到它们的值：

public interface IEquatable<Clock>
{

}
public bool Equals(Clock theObj)
{
    if (theObj == null)
    {
        return false;
    }
    if (theObj.ToString() == this.ToString())
    {
        return true;
    }
    else
    {
        return false;
    }
}

public override bool Equals(object obj)
{
   if (obj == null)
    {
        return false;
    }
    Clock clck = obj as Clock;
    if (clck == null)
    {
        return false;
    }
    else
    {
        return Equals(clck);
    }
}
public override int GetHashCode()
{
    return Hours;
}`

现在，当我尝试在不同解决方案的不同项目中使用“Equals(T)”方法比较 class 的两个实例时，它比较的是它们的值而不是它们的参考值。

覆盖一个项目中的方法是否会影响其他项目中的该方法？

我的完整代码是： `使用系统；使用 System.Diagnostics.Contracts；使用 System.Runtime.InteropServices.WindowsRuntime；使用 System.Security.Cryptography.X509Certificates;

public class Clock
{
    public int Minutes;
    public int Hours;
    public interface IEquatable<Clock>
    {

    }
    public bool Equals(Clock theObj)
    {
        if (theObj == null)
        {
            return false;
        }
        if (theObj.ToString() == this.ToString())
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public override bool Equals(object obj)
    {
       if (obj == null)
       {
           return false;
       }
       Clock clck = obj as Clock;
       if (clck == null)
       {
           return false;
       }
       else
       {
           return Equals(clck);
       }
   }
   public override int GetHashCode()
   {
       return Hours;
   }
   public override string ToString()
   {
       if (Hours < 10)
       {
           if (Minutes < 10)
           {
               return "0" + Hours + ":0" + Minutes;
           }
           else
           {
               return "0" + Hours + ":" + Minutes;
           }
       }
       else
       {
           if (Minutes < 10)
           {
               return Hours + ":0" + Minutes;
           }
           else
           {
               return Hours + ":" + Minutes;
           }
       }
   }
   public Clock(int hours, int minutes)
   {
       while (minutes > 59 || minutes < 0)
       {
           if (minutes > 59)
           {
               minutes -= 60;
               hours++;
           }
           if (minutes < 0)
           {
               minutes += 60;
               hours--;
           }
       }

       while (hours > 23 || hours < 0)
       {
           if (hours > 23)
           {
               hours -= 24;
           }

           if (hours < 0)
           {
               hours += 24;
           }
       }
       Hours = hours;
       Minutes = minutes;
   }

   public Clock Add(int minutesToAdd)
   { 
       var res = new Clock(Hours , Minutes + minutesToAdd);
       return res;
   }

   public Clock Subtract(int minutesToSubtract)
   {
       var res = new Clock(Hours , Minutes - minutesToSubtract);
       return res;
   }}

感谢您的宝贵时间！

Answer 1

你的Equals方法逻辑错误！对于类没有 ToString 方法覆盖，输出是这样的 WhosebugCodes.Clock，这导致所有对象都相等！请查看以下代码以获得更多想法：

public class Clock : IEquatable<Clock>
{
    public int Hours { get; set; }
    public int Minutes { get; set; }
    public int Seconds { get; set; }

    public bool Equals(Clock c)
    {
        if (c == null)
            return false;
        // Here is a somewhat correct logic for equality (sort of ...)
        //return c.Hours == Hours && c.Minutes == Minutes;
        return c.ToString() == this.ToString();
    }
    public override int GetHashCode() => Hours * 3600 + Minutes * 60 + Seconds;
    public override bool Equals(object obj)
    {
        var clock = obj as Clock;

        if (clock != null)
            return Equals(clock);
        return false;
    }

    public static void Main()
    {
        Clock c2 = new Clock { Hours = 12, Minutes = 01, Seconds = 59 };
        var c1 = new Clock { Hours = 12 };

        Console.WriteLine(c1.Equals(c2));
        Console.WriteLine(Equals(c1, c2));
        Console.WriteLine(c1 == c2);

        Console.WriteLine(c1.ToString());
        Console.WriteLine(c2.ToString());
    }

对于您的问题，如果您引用的 project/solution 具有您定义的 Clock 类型，那么您正在使用您定义的自定义逻辑，否则它们不应该有任何共同点。

overriding 的效果是暂时的还是永久的？

is overriding's effect temporary or permanently?

c#

methods

overriding

class

equals