我也在搜索网络寻找解决方案,但没有找到令人满意的。因此,我创建了一个通用的EqualityComparerFactory:
using System;
using System.Collections.Generic;
public static class EqualityComparerFactory
{
public static IEqualityComparer<T> Create<T>(
Func<T, int> getHashCode,
Func<T, T, bool> equals)
{
if (getHashCode == null)
{
throw new ArgumentNullException(nameof(getHashCode));
}
if (equals == null)
{
throw new ArgumentNullException(nameof(equals));
}
return new Comparer<T>(getHashCode, equals);
}
private class Comparer<T> : IEqualityComparer<T>
{
private readonly Func<T, int> _getHashCode;
private readonly Func<T, T, bool> _equals;
public Comparer(Func<T, int> getHashCode, Func<T, T, bool> equals)
{
_getHashCode = getHashCode;
_equals = equals;
}
public bool Equals(T x, T y) => _equals(x, y);
public int GetHashCode(T obj) => _getHashCode(obj);
}
}
想法是,CreateComparer方法接受两个参数:一个是GetHashCode(T)的委托,另一个是Equals(T,T)的委托。
例如:
class Person
{
public int Id { get; set; }
public string LastName { get; set; }
public string FirstName { get; set; }
}
class Program
{
static void Main(string[] args)
{
var list1 = new List<Person>(new[]{
new Person { Id = 1, FirstName = "Walter", LastName = "White" },
new Person { Id = 2, FirstName = "Jesse", LastName = "Pinkman" },
new Person { Id = 3, FirstName = "Skyler", LastName = "White" },
new Person { Id = 4, FirstName = "Hank", LastName = "Schrader" },
});
var list2 = new List<Person>(new[]{
new Person { Id = 1, FirstName = "Walter", LastName = "White" },
new Person { Id = 4, FirstName = "Hank", LastName = "Schrader" },
});
var comparer = EqualityComparerFactory.Create<Person>(
a => a.Id.GetHashCode(),
(a, b) => a.Id==b.Id);
var intersection = list1.Intersect(list2, comparer).ToList();
}
}