Attribute.GetHashCode Methode
Definition
Wichtig
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Gibt den Hashcode für diese Instanz zurück.
public:
override int GetHashCode();public override int GetHashCode ();override this.GetHashCode : unit -> intPublic Overrides Function GetHashCode () As IntegerGibt zurück
Ein 32-Bit-Hashcode als ganze Zahl mit Vorzeichen.
Beispiele
Im folgenden Codebeispiel wird die Verwendung GetHashCode im Kontext von Attribute.
using System;
using System.Reflection;
using System.Collections.Generic;
// A custom attribute to allow two authors per method.
public class AuthorsAttribute : Attribute
{
protected string _authorName1;
protected string _authorName2;
public AuthorsAttribute(string name1, string name2)
{
_authorName1 = name1;
_authorName2 = name2;
}
public string AuthorName1
{
get { return _authorName1; }
set { _authorName1 = value; }
}
public string AuthorName2
{
get { return _authorName2; }
set { _authorName2 = value; }
}
// Use the hash code of the string objects and xor them together.
public override int GetHashCode()
{
return _authorName1.GetHashCode() ^ _authorName2.GetHashCode();
}
}
// Provide the author names for each method of the class.
public class TestClass
{
[Authors("Immanuel Kant", "Lao Tzu")]
public void Method1()
{}
[Authors("Jean-Paul Sartre", "Friedrich Nietzsche")]
public void Method2()
{}
[Authors("Immanuel Kant", "Lao Tzu")]
public void Method3()
{}
[Authors("Jean-Paul Sartre", "Friedrich Nietzsche")]
public void Method4()
{}
[Authors("Immanuel Kant", "Friedrich Nietzsche")]
public void Method5()
{}
}
class Example
{
static void Main()
{
// Get the class type to access its metadata.
Type clsType = typeof(TestClass);
// Store author information in a list of tuples.
var authorsInfo = new List<Tuple<String, AuthorsAttribute>>();
// Iterate through all the methods of the class.
foreach(var method in clsType.GetMethods())
{
// Get the Authors attribute for the method if it exists.
AuthorsAttribute authAttr =
(AuthorsAttribute)Attribute.GetCustomAttribute(
method, typeof(AuthorsAttribute));
if (authAttr != null)
// Add the information to the author list.
authorsInfo.Add(Tuple.Create(clsType.Name + "." + method.Name,
authAttr));
}
// Iterate through the list
bool[] listed = new bool[authorsInfo.Count];
Console.WriteLine("Method authors:\n");
for (int ctr = 0; ctr < authorsInfo.Count; ctr++) {
var authorInfo = authorsInfo[ctr];
if (!listed[ctr]) {
Console.WriteLine("{0} and {1}", authorInfo.Item2.AuthorName1,
authorInfo.Item2.AuthorName2);
listed[ctr] = true;
Console.WriteLine(" {0}", authorInfo.Item1);
for (int ctr2 = ctr + 1; ctr2 < authorsInfo.Count; ctr2++) {
if (!listed[ctr2])
if (authorInfo.Item2.Equals(authorsInfo[ctr2].Item2)) {
Console.WriteLine(" {0}", authorsInfo[ctr2].Item1);
listed[ctr2] = true;
}
}
}
}
}
}
// The example displays the following output:
// Method authors:
//
// Immanuel Kant and Lao Tzu
// TestClass.Method1
// TestClass.Method3
// Jean-Paul Sartre and Friedrich Nietzsche
// TestClass.Method2
// TestClass.Method4
// Immanuel Kant and Friedrich Nietzsche
// TestClass.Method5
open System
open System.Reflection
open System.Collections.Generic
// A custom attribute to allow two authors per method.
[<AllowNullLiteral>]
type AuthorsAttribute(authorName1, authorName2) =
inherit Attribute()
member val AuthorName1 = authorName1
member val AuthorName2 = authorName2
// Use the hash code of the string objects and xor them together.
override _.GetHashCode() =
authorName1.GetHashCode() ^^^ authorName2.GetHashCode()
// Provide the author names for each method of the class.
type TestClass() =
[<Authors("Immanuel Kant", "Lao Tzu")>]
member _.Method1() = ()
[<Authors("Jean-Paul Sartre", "Friedrich Nietzsche")>]
member _.Method2() = ()
[<Authors("Immanuel Kant", "Lao Tzu")>]
member _.Method3() = ()
[<Authors("Jean-Paul Sartre", "Friedrich Nietzsche")>]
member _.Method4() = ()
[<Authors("Immanuel Kant", "Friedrich Nietzsche")>]
member _.Method5() = ()
// Get the class type to access its metadata.
let clsType = typeof<TestClass>
// Store author information in a array of tuples.
let authorsInfo =
[ // Iterate through all the methods of the class.
for method in clsType.GetMethods() do
// Get the Authors attribute for the method if it exists.
let authAttr =
Attribute.GetCustomAttribute(method, typeof<AuthorsAttribute>) :?> AuthorsAttribute
if authAttr <> null then
// Add the information to the author list.
$"{clsType.Name}.{method.Name}", authAttr ]
// Iterate through the list
printfn "Method authors:\n"
authorsInfo
|> List.groupBy (fun (_, authors) -> authors.AuthorName1, authors.AuthorName2)
|> List.iter (fun ((name1, name2), authors) ->
printfn $"{name1} and {name2}"
for (methodName, _) in authors do
printfn $" {methodName}")
// The example displays the following output:
// Method authors:
//
// Immanuel Kant and Lao Tzu
// TestClass.Method1
// TestClass.Method3
// Jean-Paul Sartre and Friedrich Nietzsche
// TestClass.Method2
// TestClass.Method4
// Immanuel Kant and Friedrich Nietzsche
// TestClass.Method5
Imports System.Reflection
Imports System.Collections.Generic
' A custom attribute to allow two authors per method.
<AttributeUsage(AttributeTargets.Method)> _
Public Class AuthorsAttribute : Inherits Attribute
Protected _authorName1 As String
Protected _authorName2 As String
Public Sub New(name1 As String, name2 As String)
_authorName1 = name1
_authorName2 = name2
End Sub
Public Property AuthorName1() As String
Get
Return _authorName1
End Get
Set
_authorName1 = AuthorName1
End Set
End Property
Public Property AuthorName2() As String
Get
Return _authorName2
End Get
Set
_authorName2 = AuthorName2
End Set
End Property
Public Overrides Function Equals(obj As Object) As Boolean
Dim auth As AuthorsAttribute = TryCast(obj, AuthorsAttribute)
If auth Is Nothing Then Return False
If (_authorName1 = auth._authorName1 And _authorName2 = auth._authorName2) Or
(_authorName1 = auth._authorName2 And _authorName2 = auth._authorName1)
Return True
Else
Return False
End If
End Function
' Use the hash code of the string objects and Xor them together.
Public Overrides Function GetHashCode() As Integer
Return _authorName1.GetHashCode() Xor _authorName2.GetHashCode()
End Function
End Class
' Provide the author names for each method of the class.
Public Class TestClass
<Authors("Immanuel Kant", "Lao Tzu")> _
Public Sub Method1()
End Sub
<Authors("Jean-Paul Sartre", "Friedrich Nietzsche")> _
Public Sub Method2()
End Sub
<Authors("Immanuel Kant", "Lao Tzu")> _
Public Sub Method3()
End Sub
<Authors("Jean-Paul Sartre", "Friedrich Nietzsche")> _
Public Sub Method4()
End Sub
<Authors("Immanuel Kant", "Friedrich Nietzsche")> _
Public Sub Method5()
End Sub
End Class
Public Module Example
Sub Main()
' Get the TestClass type to access its metadata.
Dim clsType As Type = GetType(TestClass)
' Store author information in a list of tuples.
Dim authorsInfo As New List(Of Tuple(Of String, AuthorsAttribute))
' Iterate through all the methods of the class.
For Each method In clsType.GetMethods()
' Get the authors attribute information
Dim authAttr As AuthorsAttribute = CType(Attribute.GetCustomAttribute(method, GetType(AuthorsAttribute)),
AuthorsAttribute)
If authAttr IsNot Nothing Then
' Add the information to the author list.
authorsInfo.Add(Tuple.Create(clsType.Name + "." + method.Name,
authAttr))
End If
Next
' Iterate through the list.
Dim listed(authorsInfo.Count - 1) As Boolean
Console.WriteLine("Method authors:")
Console.WriteLine()
For ctr As Integer = 0 To authorsInfo.Count - 1
Dim authorInfo = authorsInfo(ctr)
If Not listed(ctr)
Console.WriteLine("{0} and {1}", authorInfo.Item2.AuthorName1,
authorInfo.Item2.AuthorName2)
listed(ctr) = True
Console.WriteLine(" {0}", authorInfo.Item1)
For ctr2 As Integer = ctr + 1 To authorsInfo.Count - 1
If Not listed(ctr2)
If authorInfo.Item2.Equals(authorsInfo(ctr2).Item2) Then
Console.WriteLine(" {0}", authorsInfo(ctr2).Item1)
listed(ctr2) = true
End if
End If
Next
End If
Next
End Sub
End Module
' The example displays the following output:
' Method Authors:
'
' Immanuel Kant and Lao Tzu
' TestClass.Method1
' TestClass.Method3
' Jean-Paul Sartre and Friedrich Nietzsche
' TestClass.Method2
' TestClass.Method4
' Immanuel Kant and Friedrich Nietzsche
' TestClass.Method5