[英]C# - Dictionary - File Path (Custom EqualityComparer)
Problem: Custom Object implements EqualityComparer and IEquatable, but Dictionary doesn't always use these methods. 问题:自定义对象实现EqualityComparer和IEquatable,但是Dictionary并不总是使用这些方法。
Context: I have created a helper class, FilePath
for dealing with file paths instead of treating them as strings. 上下文:我创建了一个辅助类FilePath
来处理文件路径,而不是将它们视为字符串。 The helper class is responsible for determining if two file paths are equal. helper类负责确定两个文件路径是否相等。 I then need to store FilePaths in a Dictionary<FilePath, object>
. 然后,我需要将FilePaths存储在Dictionary<FilePath, object>
。
Goal: 目标:
Assert.True(new FilePath(@"c:\temp\file.txt").Equals(
new FilePath(@"C:\TeMp\FIle.tXt"));
var dict = new Dictionary<FilePath, object>
{
{new FilePath(@"c:\temp\file.txt"), new object()}
}
Assert.True(dict.ContainsKey(new FilePath(@"c:\temp\file.txt"));
Assert.True(dict.ContainsKey(new FilePath(@"C:\TeMp\FIle.tXt"));
I've created my FilePath class: public class FilePath : EqualityComparer, IEquatable { private string _fullPath; 我创建了FilePath类:public class FilePath:EqualityComparer,IEquatable {private string _fullPath;
public FilePath (string fullPath)
{
_fullPath = Path.GetFullPath(fullPath);
}
public override bool Equals(FilePath x, FilePath y)
{
if (null == x || null == y)
return false;
return (x._fullPath.Equals(y._fullPath, StringComparison.InvariantCultureIgnoreCase));
}
public override int GetHashCode(FilePath obj)
{
return obj._fullPath.GetHashCode();
}
public bool Equals(FilePath other)
{
return Equals(this, other);
}
public override bool Equals(object obj)
{
return Equals(this, obj as FilePathSimple);
}
}
Question: 题:
Assert 1 and 2 pass, but Assert 3 fails: 断言1和2通过,但断言3失败:
Assert.True(dict.ContainsKey(new FilePath(@"C:\TeMp\FIle.tXt"));
I needed to override GetHashCode() as well: 我还需要重写GetHashCode():
public override int GetHashCode()
{
return _fullPath.ToLower().GetHashCode();
}
References: What's the role of GetHashCode in the IEqualityComparer<T> in .NET? 参考: .NET中IEqualityComparer <T>中GetHashCode的作用是什么?
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