测试两个对象是否相等

Question

我正在尝试从头开始创建一个find方法，看看两个对象是否相等，只要某些方法的结果相等，使用Equals方法就可以了。我知道使用Find / Contains方法会更快，但我不允许使用它们。该方法的签名为“static int Find(List c, Coffee x)”在x中查找搜索c并返回有效索引（例如，0，1）{{1存在于x中，否则返回c。必须使用equals方法来确定等效性。如果传递的对象不等于列表中当前的对象，则将其添加到列表中（该列表包含从基类派生的两种类型的对象，因此列表可以存储这两种类型）。等效性由-1，name，cost，demand和holding cost(h)定义为常规和roasttype(M)，name，{{对于cost，1}}，demand和holding cost(h)。这是我到目前为止所做的（很多代码可能写得更好）：

minimum quantity(also M)

}

decaf

}

class EOQCalculator4
{
    static void Main(string[] args)
    {

        // Create objects and references
        Coffee obv = new Coffee();
        Decaf decafCoffee = null;
        Regular regularCoffee = null;
        List<Coffee> inventory = new List<Coffee>();


        // Prompt user for input and store it as a string
        Console.Write("Enter q to quit or the whole data as a comma delimited string using the following format Name,D,C,D:minQ or R:roast ");
        string s = Console.ReadLine();

        // Loop
        while (!s.ToLower().Equals("q"))
        {
            // Split string up and assign componets to variables
            string[] values = s.Split(",".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
            string name = values[0];
            string demand = (values[1]);
            string cost = (values[2]);
            string type = values[3];

            // Check for > 0 and convert to numbers
            float D = CheckDemand(demand);
            float C = CheckCost(cost);
            float M = 0;

            if (type.StartsWith("D:"))
            {
                type = Regex.Match(type, @"\d+").Value;
                M = CheckMin(type);
                decafCoffee = new Decaf(name, D, C, M);
                inventory.Add(decafCoffee);
            }

            else if (type.StartsWith("R:"))
            {
                if (type.Contains("light"))
                {
                    M = 1;
                    regularCoffee = new Regular(name, D, C, M);
                    inventory.Add(regularCoffee);
                }
                else if (type.Contains("medium"))
                {
                    M = 2;
                    regularCoffee = new Regular(name, D, C, M);
                    inventory.Add(regularCoffee);
                }

                else if (type.Contains("dark"))
                {
                    M = 3;
                    regularCoffee = new Regular(name, D, C, M);
                    inventory.Add(regularCoffee);
                }
                else Console.WriteLine("\nError, please enter all lower case \"dark\", \"medium\", or \"light\" next time.");
            }

            else Console.WriteLine("\nError, please enter either \"D:\" followed by a number or \"R:\" followed by roast type next time.");
            Console.Write("\nEnter q to quit or the whole data as a comma delimited string using the following format Name,D,C,D:minQ or R:roast: ");
            s = Console.ReadLine();
        }   // End loop

        // Sort and  display values
        var sortedList = inventory.OrderBy(i => i.Q()).ToList();
        Console.WriteLine("\nName \t   C ($)      Demand \t  Detail   Q(lbs.)     TAC ($)      T(weeks) ");
        for (int j = 0; j < inventory.Count; j++)
        {
            Console.WriteLine("{0}", sortedList[j].toString());
        }

        Console.WriteLine(obv.toStringQ());

    }

#region CheckMethods
    // Data validation methods
    public static float CheckDemand(String R)
    {
        float number;
        while (!float.TryParse(R, out number) || number <= 0)
        {
            Console.Write("Please enter a number greater than 0 for demand: ");
            R = Console.ReadLine();

        }   return number;

    }

    public static float CheckCost(String R)
    {
        float number;
        while (!float.TryParse(R, out number) || number <= 0)
        {
            Console.Write("Please enter a number greater than 0 for cost: ");
            R = Console.ReadLine();

        } return number;

    }

    public static float CheckMin(String R)
    {
        float number;
        while (!float.TryParse(R, out number) || number <= 0)
        {
            Console.Write("Please enter a number greater than 0 for minimum quantity: ");
            R = Console.ReadLine();

        } return number;

    }

 public class Coffee
{
    // Members
    private static float sumQ = 0;
    private static int mcount;
    private float k = 20;
    private float mc;
    private string mName;
    private float md;
    private float q;
    private float mh;
    private float tac;
    private float min = 0;
    private float type = 0;
    Coffee i = new Coffee();

    public override bool Equals(object obj)
    {
        if (obj is Coffee)
        {
            bool isNameEqual = i.Name.Equals(this.Name);
            bool isuCostEqual = i.Cost.Equals(this.Cost);
            bool isDemandEqual = i.Demand.Equals(this.Demand);
            bool ishCostEqual = i.h.Equals(this.h);
            bool isMinEqual = i.getMin.Equals(this.min);
            return (isNameEqual && isuCostEqual && isDemandEqual && ishCostEqual && isMinEqual);
        }
        return false;
    }

    // Default Constructor
    public Coffee()
    { mcount = 0; }

    // Full Constructor
    public Coffee(string Name, float d, float c, float m)
    {
        mName = Name;
        md = d;
        mc = c;
        mh = (float).30 * mc;
        type = m;
        min = m;
        mcount++;
    }

    public Coffee(string Name, float d, float c)
    {
        mName = Name;
        md = d;
        mc = c;
        mh = (float).30 * mc;
        mcount++;
    }

    // Copy Constructor
    public Coffee(Coffee e)
    {
        this.mName = e.mName;
        this.md = e.md;
        this.mh = e.mh;
        this.mc = e.mc;
        this.q = e.q;
        mcount++;
    }

    // Destructor
    ~Coffee()
    { mcount--; }

    // Properties
    #region Properties

    public float getMin
    {
        get { return min; }
    }

    public float getType
    {
        get { return type; }
    }

    public string Name
    {
        get { return mName; }
    }

    public float h
    {
        get { return mh; }
    }

    public float Cost
    {
        get { return mc; }
    }

    public float Demand
    {
        get { return md; }
    }

    public float getQ
    {
        get { return q; }
    }

    public float K
    {
        get { return k; }
    }

    public float getSumQ
    {
        get { return sumQ; }
        set { sumQ = value; }
    }
    #endregion

    // Methods
    public virtual float Q()
    {
        q = (float)Math.Sqrt(2 * md * k / mh);
        sumQ += q;
        return q;
    }

    public virtual float TAC()
    {
        tac = q / 2 * mh + md * k / q + md * mc;
        return tac;
    }

    public virtual float T()
    {
        float t = (q / (md / 52));
        return t;
    }

    public virtual string toString()
    {
        string a = String.Format("{0,-10:s} {1,-10:f2} {2,-13:f0} {3,-11:f0} {4,-11:f2} {5,-0:f2}", mName, mc, md, Q(), TAC(), T());
        return a;
    }

    public virtual string toStringQ()
    {
        string c = String.Format("\nIf you purchase all of the coffee you will need space to hold {0,-0:f2} of coffee", sumQ);
        return c;
    }
}

}

假设我正确实现了equals方法，在哪里/如何实现“public class Decaf : Coffee { // Members private float k = 30; private float min; private float q; // Constructor public Decaf(string Name, float d, float c, float m) : base(Name, d, c) { min = m; } // Methods public override float Q() { q = (float)Math.Sqrt(2 * Demand * k / h); if (q < min) { return min; } else return q; } public override float TAC() { getSumQ += Q(); return Q() / 2 * h + Demand * k / Q() + Demand * Cost; } public override float T() { return (Q() / (Demand / 52)); } public override string toString() { string a = String.Format("{0,-11:s}{1,-11:f2}{2,-12:f0}{3,-9:f0}{4,-12:f0}{5,-13:f2}{6,-10:f2}", Name, Cost, Demand, min, Q(), TAC(), T()); return a; } } ”方法？

Answer 1

因为它被覆盖的Equals方法将无法正常工作。等于测试参考相等性，即两个对象引用是否指向同一个对象。有关Equals的详细信息，请参阅MSDN。

如果您只是想确保不添加相同的两个咖啡（具有相同的名称，需求成本和类型），那么您可以对这些字段执行简单的值检查，例如（添加到您的方法）咖啡班）

public bool CoffeeIsSame(Coffee c2)
{
    return (this.Name == c2.Name) && (this.Demand == this.Demand) && (this.Cost == c2.Cost) && (this.Type == c2.Type); 
}

你的Find方法看起来像这样：

static bool Find(List c, Coffee x)
{
    bool result = false; 
    foreach(Coffee coffee in c)
    {
        result = coffee.CoffeeIsSame(x); 
        if (result) 
        {
             break;
        }
    }
    return result;
}

要实现静态Find方法，可以将其添加到Coffee类中。然后你这样称呼它（使用你的Main方法中的一些代码作为例子）：

...
else if (type.Contains("dark"))
{
    M = 3;
    regularCoffee = new Regular(name, D, C, M);
    if (!Coffee.Find(inventory, regularCoffee))
    {
        inventory.Add(regularCoffee);
    }
}
...

希望有所帮助，

欢呼声