使用Dictionary覆盖对象的等于 . C＃-Java 学习之路

如何重写Equals，这样你可以比较两个相同的类和两个目录而不用静态指定它们？目前，有一个由以下字段组成的对象 . 对于类型字符串，Int32等，等于满足条件 .

public class RatiosAVG
{
    public RatiosAVG()
    {
        Dict1 = new Dictionary<Int32, OtherObject1>();
        Dict2 = new Dictionary<Int32, OtherObject2>();
    }

    public OtherObject1 Obj { get; set; }
    public Dictionary<Int32, OtherObject1> Dict1 { get; set; }
    public Dictionary<Int32, OtherObject2> Dict2 { get; set; }
    public String Name { get; set; }
    public Int32 Value { get; set; }

    public override bool Equals(Object obj)
    {
        try
        {
            if (!(obj is RatiosAVG))
                return false;

            RatiosAVG other = (RatiosAVG)obj;
            Type type = typeof(RatiosAVG);
            foreach (System.Reflection.PropertyInfo property in type.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance))
            {

                Object selfValue = type.GetProperty(property.Name).GetValue(this, null);
                Object otherValue = type.GetProperty(property.Name).GetValue(other, null);

                if ((selfValue == null || !selfValue.Equals(otherValue)) && selfValue != otherValue)
                        return false;
            }

            if (type.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance).Count() == 0) 
               return false; 
            else 
               return true;
        }
        catch (Exception) { return false; }
    }
}

OtherObject1和OtherObject2是Object

1 回答

您的代码中存在许多问题：

检查简单案例（例如 obj == null ）
使用 as 而不是 is ()
不抛弃所有异常
当有三个不同的属性进行比较时，不要使用Reflection

可能的实现可以

public override Boolean Equals(Object obj) {
    // If obj is actually "this" then true
    if (Object.ReferenceEquals(this, obj))
      return true;

    // "as " is better the "is" + "(RatiosAVG)" 
    RatiosAVG other = obj as RatiosAVG;

    // obj is either null or not a RatiosAVG
    if (Object.ReferenceEquals(null, other))
      return false;

    // When you have 3 properties to compare, reflection is a bad idea 
    if (other.Value != Value)
      return false;
    else if (!String.Equals(other.Name, Name, StringComparison.Ordinal))
      return false;
    else if (!Object.Equals(other.Obj, Obj))
      return false;

    // Finally, dictionaries. If, the criterium is: 
    // "Dictionaries are considered being equal if and only 
    // if they have the same {key, value} pairs"
    // you can use Linq: SequenceEqual. 
    // Otherwise you should provide details for the dictionaries comparison
    if (!Enumerable.SequenceEqual(other.Dict1, Dict1))
      return false;
    else if (!Enumerable.SequenceEqual(other.Dict2, Dict2))
      return false;

    return true;
  }

  // Do not forget to override GetHashCode:
  public override int GetHashCode() {
    return Value; // <- Simplest version; probably you have to put more elaborated one
  }

回复于 2024-05-05T11:46:36+08:00

使用Dictionary覆盖对象的等于 . C＃

1 回答

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