C#：GetHashCode、Equals 和 Dictionary 导致 IndexOutOfRangeException？

发布于 2024-12-09 01:22:23 字数 1505 浏览 1 评论 0原文

可能的重复：
字典何时在 Add 或时抛出 IndexOutOfRangeException包含Key？

这个很时髦。我无法轻松地探究到底。在日志中发现异常，挖出了一些旧代码。不要问我为什么这样写，因为我不知道。问题实际上是在设置字典的 Item 时抛出 IndexOutOfRangeException 的条件是什么。事情是这样的：

public MyEnum { Undefined = 0, B = 1, C = 2, D = 16, All = B | C | D }

public class MC 
{
  private int _hashCode;
  private int _i;
  private MyEnum _e;

  public MC(int i, MyEnum e)
  {
     _i = i;
     _e = e;
     SetHashCode();
  }

  private SetHashCode()
  {
    _hashCode = _i * 31 + (int)e;
  }

  public override bool Equals(object other)
  {
    if (!(obj is MC))
    {
      return false;
    }
    MC other = (MC)obj;
    return ((_i == other._i) && (_e == other._e));
  }

  public override int GetHashCode()
  {
    return _hashCode;
  }
}

...

var d = new Dictionary<MC, DateTime>();
...
// Create and populate the list of MCs
var mcs = new List<MC>();
...
foreach (MC mc in mcs) 
{
  ...
  d[mc] = DateTime.UtcNow; // Pukes here
}

例外是：

System.IndexOutOfRangeException, Source: mscorlib    Index was outside the bounds of the array.       at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)

想法如何使生产线失败？不要将你的注意力转移到错误的方向，但我认为 Equals 和 GetHashCode 有一些可疑的地方，但到目前为止我无法证明这一点 - 没有使用单元测试框架进行重现。

原文

Possible Duplicate:
When does a dictionary throw an IndexOutOfRangeException on Add or ContainsKey?

This one is funky. I can't get to the bottom of it with ease. Found an exception in the log and dug out some old code. Don't ask me about why this is written this way because I have no idea. The question really is what could be conditions for IndexOutOfRangeException to be thrown when the Item of the dictionary is being set. Here is how the thing looks:

public MyEnum { Undefined = 0, B = 1, C = 2, D = 16, All = B | C | D }

public class MC 
{
  private int _hashCode;
  private int _i;
  private MyEnum _e;

  public MC(int i, MyEnum e)
  {
     _i = i;
     _e = e;
     SetHashCode();
  }

  private SetHashCode()
  {
    _hashCode = _i * 31 + (int)e;
  }

  public override bool Equals(object other)
  {
    if (!(obj is MC))
    {
      return false;
    }
    MC other = (MC)obj;
    return ((_i == other._i) && (_e == other._e));
  }

  public override int GetHashCode()
  {
    return _hashCode;
  }
}

...

var d = new Dictionary<MC, DateTime>();
...
// Create and populate the list of MCs
var mcs = new List<MC>();
...
foreach (MC mc in mcs) 
{
  ...
  d[mc] = DateTime.UtcNow; // Pukes here
}

And the exception is:

System.IndexOutOfRangeException, Source: mscorlib    Index was outside the bounds of the array.       at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)

Ideas how to make the line to fail? Don't what to diverge your attention to the wrong direction but I thought there was something fishy with the Equals and GetHashCode but I couldn't prove it so far - no repro using a unit testing framework.

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