相关疑难解决方法(0)

在.NET GetHashCode方法中,很多地方都使用.NET 方法.特别是在快速查找集合中的项目或确定相等性时.是否有关于如何GetHashCode为我的自定义类实现覆盖的标准算法/最佳实践,因此我不会降低性能？

鉴于以下课程

public class Foo
{
    public int FooId { get; set; }
    public string FooName { get; set; }

    public override bool Equals(object obj)
    {
        Foo fooItem = obj as Foo;

        if (fooItem == null) 
        {
           return false;
        }

        return fooItem.FooId == this.FooId;
    }

    public override int GetHashCode()
    {
        // Which is preferred?

        return base.GetHashCode();

        //return this.FooId.GetHashCode();
    }
}

我已经覆盖了该Equals方法,因为它Foo代表了Foos表的一行.哪个是覆盖的首选方法GetHashCode？

覆盖为什么重要GetHashCode？

我有一个班级IComparable:

public class a : IComparable
{
    public int Id { get; set; }
    public string Name { get; set; }

    public a(int id)
    {
        this.Id = id;
    }

    public int CompareTo(object obj)
    {
        return this.Id.CompareTo(((a)obj).Id);
    }
}

当我将这个类的对象列表添加到哈希集时:

a a1 = new a(1);
a a2 = new a(2);
HashSet<a> ha = new HashSet<a>();
ha.add(a1);
ha.add(a2);
ha.add(a1);

一切都很好,ha.count是2的,但:

a a1 = new a(1);
a a2 = new a(2);
HashSet<a> ha = new HashSet<a>();
ha.add(a1); …

考虑以下:

class Bind
{
    public string x { get; set; }
    public string y { get; set; }
}
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        ObservableCollection<Bind> cX = new ObservableCollection<Bind>();
        ObservableCollection<Bind> cY = new ObservableCollection<Bind>();
        cX.Add(new Bind { x = "a", y = "1" });
        cX.Add(new Bind { x = "b", y = "2" });
        cY.Add(new Bind { x = "a", y = "1" });
        foreach (var …