Attribute.GetHashCode メソッド

.NET Framework クラス ライブラリ リファレンス

Attribute.GetHashCode メソッド

このインスタンスのハッシュ コードを返します。

名前空間: System
アセンブリ: mscorlib (mscorlib.dll 内)
構文

Visual Basic (宣言)

Public Overrides Function
 GetHashCode As Integer

Visual Basic (使用法)

Dim instance As Attribute
Dim returnValue As Integer

returnValue = instance.GetHashCode

C#

public override int GetHashCode ()

C++

public:
virtual int GetHashCode () override

J#

public int GetHashCode ()

JScript

public override function GetHashCode () : int

戻り値
32 ビット符号付き整数ハッシュ コード。

使用例

Attribute のコンテキストでの GetHashCode の使用方法を次のコード例に示します。

Visual Basic

Imports System
Imports System.Reflection
Imports System.Collections

Module HashCodeVB

    ' Visual Basic requires that the AttributeUsage be specified.
    ' A custom attribute to allow two authors per method.
    <AttributeUsage(AttributeTargets.All.Method)> _
    Public Class AuthorsAttribute
        Inherits Attribute

        Public Sub New(ByVal
 name1 As String, ByVal
 name2 As String)
            myAuthorName1 = name1
            myAuthorName2 = name2
        End Sub

        Protected myAuthorName1 As String
        Protected myAuthorName2 As String

        Public Property AuthorName1() As
 String
            Get
                Return myAuthorName1
            End Get
            Set(ByVal Value As
 String)
                myAuthorName1 = AuthorName1
            End Set
        End Property

        Public Property AuthorName2() As
 String
            Get
                Return myAuthorName2
            End Get
            Set(ByVal Value As
 String)
                myAuthorName2 = AuthorName2
            End Set
        End Property

        ' Use the hash code of the string objects and Xor them together.
        Public Overrides Function
 GetHashCode() As Integer
            Return myAuthorName1.GetHashCode() Xor
 myAuthorName2.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

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Use a hash table to store the hash codes and methods.
        Dim hTable As Hashtable = New
 Hashtable()
        Dim mInfo As MethodInfo
        ' Iterate through all the methods of the class.
        For Each mInfo In
 clsType.GetMethods()
            ' Get the unique hash code for these authors.
            Dim attr As Attribute = Attribute.GetCustomAttribute(mInfo,
 GetType(AuthorsAttribute))
            If Not attr Is
 Nothing Then
                Dim authAttr As AuthorsAttribute
 = CType(attr, _
                    AuthorsAttribute)
                Dim hCode As Integer
 = authAttr.GetHashCode()
                ' See if it's already been added to the hash table.
                If hTable.Contains(hCode) Then
                    Dim o As Object
 = hTable(hCode)
                    If TypeOf o Is
 ArrayList Then
                        ' If so, retrieve the array using the Item syntax.
                        Dim al As ArrayList
 = CType(o, ArrayList)
                        ' Add the method to the array list.
                        al.Add(mInfo.Name)
                        ' Put the edited array list back into the table.
                        hTable(hCode) = al
                    End If
                ' This is the first occurrence of this hash code.
                Else
                    ' Create a new array list.
                    Dim al As ArrayList = New
 ArrayList()
                    ' Add the method name as the first entry.
                    al.Add(mInfo.Name)
                    ' Add the new hash code and array list to the table.
                    hTable.Add(hCode, al)
                End If
            End If
        Next

        ' Get the hash table's enumerator and iterate through the table.
        Dim dictEnum As IDictionaryEnumerator
 = hTable.GetEnumerator
        While dictEnum.MoveNext()
            ' Get the array list for this iteration.
            Dim o As Object
 = dictEnum.Value
            If TypeOf o Is
 ArrayList Then
                Dim al As ArrayList = CType(o,
 ArrayList)
                Dim i As Integer
                ' Access each element of the array.
                for i = 0 to al.Count - 1
                    ' For the first element, retrieve the author names.
                    If i = 0 Then
                        Dim methodName as Object
 = al(i)
                        ' Get the metadata for the method.
                        Dim mInfo2 As MethodInfo
 = _
                            clsType.GetMethod(CType(methodName, String))
                        ' Retrieve the Authors attribute again.
                        Dim attr As Attribute
 = Attribute.GetCustomAttribute( _
                            mInfo2, GetType(AuthorsAttribute))
                        If Not attr Is
 Nothing And _
                            TypeOf attr Is
 AuthorsAttribute Then
                            ' Convert the attribute to access its data.
                            Dim authAttr As
 AuthorsAttribute = _
                                CType(attr, AuthorsAttribute)
                            ' Display the author's names.
                            Console.WriteLine("Authors: {0}, {1}",
 _
                                authattr.AuthorName1, authattr.AuthorName2)
                        Else
                            Console.WriteLine("The authors could
 not " + _
                                "be retrieved.")
                        End If
                    End If
                    ' Display each method authored by this team.
                    Console.WriteLine(al(i))
                Next i
                Console.WriteLine("")
            End If
        End While
    End Sub
End Module

C#

using System;
using System.Reflection;
using System.Collections;

namespace HashCodeCS 
{
    // A custom attribute to allow two authors per method.
    public class AuthorsAttribute : Attribute
 
    {
        public AuthorsAttribute(string name1,
 string name2) 
        {
            authorName1 = name1;
            authorName2 = name2;
        }

        protected string authorName1;
        protected string authorName2;
    
        public string AuthorName1 
        {
            get { return authorName1; }
            set { authorName1 = AuthorName1; }
        }

        public string AuthorName2 
        {
            get { return authorName2; }
            set { authorName2 = AuthorName2; }
        }

        // 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 DemoClass 
    {
        static void Main(string[]
 args) 
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);

            // Use a hash table to store the hash codes and methods.
            Hashtable hTable = new Hashtable();

            // Iterate through all the methods of the class.
            foreach(MethodInfo mInfo in clsType.GetMethods())
 
            {
                // Get the Authors attribute for the method if it exists.
                AuthorsAttribute authAttr = 
                    (AuthorsAttribute)Attribute.GetCustomAttribute(
                    mInfo, typeof(AuthorsAttribute));
                if (authAttr != null) 
                {
                    // Get the unique hash code for these authors.
                    int hCode = authAttr.GetHashCode();

                    // See if it's already been added to the hash table.
                    if (hTable.Contains(hCode)) 
                    {
                        // If so, retrieve the array using the Item
 syntax.
                        ArrayList al = (ArrayList)hTable[hCode];
                        // Add the method to the array list.
                        al.Add(mInfo.Name);
                        // Put the edited array list back into the table.
                        hTable[hCode] = al;
                    }

                        // This is the first occurrence of this hash
 code.
                    else 
                    {
                        // Create a new array list.
                        ArrayList al = new ArrayList();
                        // Add the method name as the first entry.
                        al.Add(mInfo.Name);
                        // Add the new hash code and array list to the
 table.
                        hTable.Add(hCode, al);
                    }
                }
            }

            // Get the hash table's enumerator and iterate through the
 table.
            IDictionaryEnumerator dictEnum = hTable.GetEnumerator();
            while (dictEnum.MoveNext()) 
            {
                // Get the array list for this iteration.
                ArrayList al = (ArrayList)dictEnum.Value;
                // Access each element of the array.
                for (int i=0; i<al.Count;
 i++) 
                {
                    // For the first element, retrieve the author names.
                    if (i == 0) 
                    {
                        // Get the metadata for the method.
                        MethodInfo mInfo = clsType.GetMethod((String)al[i]);
                        // Retrieve the Authors attribute again.
                        AuthorsAttribute authAttr = 
                            (AuthorsAttribute)Attribute.GetCustomAttribute(
                            mInfo, typeof(AuthorsAttribute));
                        // Display the authors names.
                        if (authAttr != null)
                            Console.WriteLine("Authors: {0}, {1}", 
                                authAttr.AuthorName1, authAttr.AuthorName2);
                        else
                            Console.WriteLine("The authors could not be retrieved.");
                    }
                    // Display each method authored by this team.
                    Console.WriteLine(al[i]);
                }
                Console.WriteLine("");
            }
        }
    }
}

C++

using namespace System;
using namespace System::Reflection;
using namespace System::Collections;

// A custom attribute to allow two authors per method.
public ref class AuthorsAttribute: public
 Attribute
{
public:
   AuthorsAttribute( String^ name1, String^ name2 )
   {
      authorName1 = name1;
      authorName2 = name2;
   }

protected:
   String^ authorName1;
   String^ authorName2;

public:
   property String^ AuthorName1 
   {
      String^ get()
      {
         return authorName1;
      }

      void set( String^ value )
      {
         authorName1 = value;
      }
   }

   property String^ AuthorName2 
   {
      String^ get()
      {
         return authorName2;
      }

      void set( String^ value )
      {
         authorName2 = value;
      }
   }

   // Use the hash code of the string objects and xor them together.
   virtual int GetHashCode() override
   {
      return authorName1->GetHashCode() ^ authorName2->GetHashCode();
   }
};

// Provide the author names for each method of the class.
public ref class TestClass
{
public:

   [Authors("Immanuel Kant","Lao Tzu")]
   void Method1(){}

   [Authors("Jean-Paul Sartre","Friedrich Nietzsche")]
   void Method2(){}

   [Authors("Immanuel Kant","Lao Tzu")]
   void Method3(){}

   [Authors("Jean-Paul Sartre","Friedrich Nietzsche")]
   void Method4(){}

   [Authors("Immanuel Kant","Friedrich Nietzsche")]
   void Method5(){}
};

int main()
{
   // Get the class type to access its metadata.
   Type^ clsType = TestClass::typeid;

   // Use a hash table to store the hash codes and methods.
   Hashtable^ hTable = gcnew Hashtable;

   // Iterate through all the methods of the class.
   IEnumerator^ myEnum = clsType->GetMethods()->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      MethodInfo^ mInfo = safe_cast<MethodInfo^>(myEnum->Current);

      // Get the Authors attribute for the method if it exists.
      AuthorsAttribute^ authAttr = dynamic_cast<AuthorsAttribute^>(Attribute::GetCustomAttribute(
 mInfo, AuthorsAttribute::typeid ));
      if ( authAttr != nullptr )
      {
         // Get the unique hash code for these authors.
         int hCode = authAttr->GetHashCode();

         // See if it's already been added to the hash table.
         if ( hTable->Contains( hCode ) )
         {
            // If so, retrieve the array using the Item syntax.
            ArrayList^ al = dynamic_cast<ArrayList^>(hTable[ hCode ]);

            // Add the method to the array list.
            al->Add( mInfo->Name );

            // Put the edited array list back into the table.
            hTable[ hCode ] = al;
         }
         // This is the first occurrence of this hash code.
         else
         {
            // Create a new array list.
            ArrayList^ al = gcnew ArrayList;

            // Add the method name as the first entry.
            al->Add( mInfo->Name );

            // Add the new hash code and array list to the table.
            hTable->Add( hCode, al );
         }
      }
   }
   
   // Get the hash table's enumerator and iterate through the table.
   IDictionaryEnumerator^ dictEnum = hTable->GetEnumerator();
   while ( dictEnum->MoveNext() )
   {
      // Get the array list for this iteration.
      ArrayList^ al = dynamic_cast<ArrayList^>(dictEnum->Value);
      
      // Access each element of the array.
      for ( int i = 0; i < al->Count;
 i++ )
      {
         // For the first element, retrieve the author names.
         if ( i == 0 )
         {
            // Get the metadata for the method.
            MethodInfo^ mInfo = clsType->GetMethod( dynamic_cast<String^>(al[
 i ]) );

            // Retrieve the Authors attribute again.
            AuthorsAttribute^ authAttr = dynamic_cast<AuthorsAttribute^>(Attribute::GetCustomAttribute(
 mInfo, AuthorsAttribute::typeid ));

            // Display the authors names.
            if ( authAttr != nullptr )
                        Console::WriteLine( "Authors: {0}, {1}", authAttr->AuthorName1,
 authAttr->AuthorName2 );
            else
                        Console::WriteLine( "The authors could not be retrieved."
 );
         }
         // Display each method authored by this team.
         Console::WriteLine( al[ i ] );
      }
      Console::WriteLine( "" );
   }
}

J#

package HashCodeJSL; 

import System.*;
import System.Reflection.*;
import System.Collections.*;

// A custom attribute to allow two authors per method.
/** @attribute System.AttributeUsageAttribute(AttributeTargets.Method)
 */
public class AuthorsAttribute extends Attribute
{
    public AuthorsAttribute(String name1, String name2)
    {
        authorName1 = name1;
        authorName2 = name2;
    } //AuthorsAttribute

    protected String authorName1;
    protected String authorName2;

    /** @property 
     */
    public String get_AuthorName1()
    {
        return authorName1;
    } //get_AuthorName1

    /** @property 
     */
    public void set_AuthorName1(String value)
    {
        authorName1 = value;
    } //set_AuthorName1

    /** @property 
     */
    public String get_AuthorName2()
    {
        return authorName2;
    } //get_AuthorName2

    /** @property 
     */
    public void set_AuthorName2(String value)
    {
        authorName2 = value;
    } //set_AuthorName2

    // Use the hash code of the string objects and xor them together.
    public int GetHashCode()
    {
        return authorName1.GetHashCode() ^ authorName2.GetHashCode();
    } //GetHashCode
} //AuthorsAttribute

// Provide the author names for each method of the class.
public class TestClass
{
    /** @attribute Authors("Immanuel Kant", "Lao Tzu")
     */
    public void Method1()
    {
    } //Method1

    /** @attribute Authors("Jean-Paul Sartre", "Friedrich Nietzsche")
     */
    public void Method2()
    {
    } //Method2

    /** @attribute Authors("Immanuel Kant", "Lao Tzu")
     */
    public void Method3()
    {
    } //Method3

    /** @attribute Authors("Jean-Paul Sartre", "Friedrich Nietzsche")
     */
    public void Method4()
    {
    } //Method4

    /** @attribute Authors("Immanuel Kant", "Friedrich Nietzsche")
     */
    public void Method5()
    {
    } //Method5
} //TestClass

class DemoClass
{
    public static void main(String[]
 args)
    {
        // Get the class type to access its metadata.
        Type clsType = TestClass.class.ToType();

        // Use a hash table to store the hash codes and methods.
        Hashtable hTable = new Hashtable();

        // Iterate through all the methods of the class.           
 
        for (int iCtr = 0; iCtr < clsType.GetMethods().length;
 iCtr++) {
            MethodInfo mInfo = (MethodInfo)clsType.GetMethods()[iCtr];

            // Get the Authors attribute for the method if it exists.
            AuthorsAttribute authAttr = (AuthorsAttribute)Attribute.
                GetCustomAttribute(mInfo, AuthorsAttribute.class.ToType());

            if (authAttr != null) {
                // Get the unique hash code for these authors.
                int hCode = authAttr.GetHashCode();

                // See if it's already been added to the hash table.
                if (hTable.Contains((Int32)hCode)) {
                    // If so, retrieve the array using the Item syntax.
                    ArrayList al = (ArrayList)hTable.get_Item((Int32)hCode);

                    // Add the method to the array list.
                    al.Add(mInfo.get_Name());

                    // Put the edited array list back into the table.
                    hTable.set_Item((Int32)hCode, al);
                }
                // This is the first occurrence of this hash code.
                else {
                    // Create a new array list.
                    ArrayList al = new ArrayList();

                    // Add the method name as the first entry.
                    al.Add(mInfo.get_Name());

                    // Add the new hash code and array list to the table.
                    hTable.Add((Int32)hCode, al);
                }
            }
        }

        // Get the hash table's enumerator and iterate through the table.
        IDictionaryEnumerator dictEnum = hTable.GetEnumerator();

        while (dictEnum.MoveNext()) {
            // Get the array list for this iteration.
            ArrayList al = (ArrayList)dictEnum.get_Value();

            // Access each element of the array.
            for (int i = 0; i < al.get_Count();
 i++) {
                // For the first element, retrieve the author names.
                if (i == 0) {
                    // Get the metadata for the method.
                    MethodInfo mInfo = clsType.GetMethod((String)al.
                        get_Item(i));

                    // Retrieve the Authors attribute again.
                    AuthorsAttribute authAttr = (AuthorsAttribute)Attribute.
                        GetCustomAttribute(mInfo,
                        AuthorsAttribute.class.ToType());

                    // Display the authors names.
                    if (authAttr != null) {
                        Console.WriteLine("Authors: {0}, {1}",authAttr.
                            get_AuthorName1(), authAttr.get_AuthorName2());
                    }
                    else {
                        Console.WriteLine("The authors could not be " 
                            + "retrieved.");
                    }
                }

                // Display each method authored by this team.
                Console.WriteLine(al.get_Item(i));
            }
            Console.WriteLine("");
        }
    } //main
} //DemoClass

JScript

import System;
import System.Reflection;
import System.Collections;

package HashCodeJS {
    // A custom attribute to allow 2 authors per method.
    public AttributeUsage(AttributeTargets.Method) class
 AuthorsAttribute extends Attribute {
        public function AuthorsAttribute(name1
 : String, name2 : String) {
            authorName1 = name1;
            authorName2 = name2;
        }

        protected var authorName1 : String;
        protected var authorName2 : String;
    
        public function get
 AuthorName1() : String {
            return authorName1; 
                }

                public function set
 AuthorName1(AuthorName1 : String) {
            authorName1 = AuthorName1; 
                }

        public function get
 AuthorName2() : String{
            return authorName2; 
                }

                public function set
 AuthorName2(AuthorName2 : String) {
            authorName2 = AuthorName2; 
        }

        // Use the hash code of the string objects and xor them together.
        public override function GetHashCode()
 : int {
            return authorName1.GetHashCode() ^ authorName2.GetHashCode();
        }
    }

    // Provide the author names for each method of the class.
    public class TestClass {
        public AuthorsAttribute("Immanuel Kant", "Lao
 Tzu")
        function Method1()
        {}

        public AuthorsAttribute("Jean-Paul Sartre",
 "Friedrich Nietzche")
        function Method2()
        {}

        public AuthorsAttribute("Immanuel Kant", "Lao
 Tzu")
        function Method3()
        {}

        public AuthorsAttribute("Jean-Paul Sartre",
 "Friedrich Nietzche")
        function Method4()
        {}

        public AuthorsAttribute("Immanuel Kant", "Friedrich
 Nietzche")
        function Method5()
        {}
    }

    class DemoClass {
        static function Main() {
            // Get the class type to access its metadata.
                        var testclass : TestClass = new
 TestClass();
            var clsType : Type = testclass.GetType();

            // Use a hash table to store the hash codes and methods.
            var hTable : Hashtable = new Hashtable();

            // Iterate through all the methods of the class.
                        var mInfo : MethodInfo[] = clsType.GetMethods()
            for (var i : int
 = 0; i < mInfo.length; i++) {
                // Get the Authors attribute for the method if it exists.
                var attr : Attribute = Attribute.GetCustomAttribute(mInfo[i],
 AuthorsAttribute);
                if (attr != null) {
                    // Get the unique hash code for these authors.
                    var hCode : int = attr.GetHashCode();

                    // See if it's already been added to the hash table.
                    if (hTable.Contains(hCode)) {
                        // If so, retrieve the array import the Item
 syntax.
                        var al : ArrayList = ArrayList(hTable[hCode]);
                        // Add the method to the array list.
                        al.Add(mInfo[i].Name);
                        // Put the edited array list back into the table.
                        hTable[hCode] = al;
                    }

                    // This is the first occurrence of this hash code.
                    else {
                        // Create a new array list.
                        var al2 : ArrayList = new
 ArrayList();
                        // Add the method name as the first entry.
                        al2.Add(mInfo[i].Name);
                        // Add the new hash code and array list to the
 table.
                        hTable.Add(hCode, al2);
                    }
                }
            }

            // Get the hash table's enumerator and iterate through the
 table.
            var dictEnum : IDictionaryEnumerator = hTable.GetEnumerator();
            while (dictEnum.MoveNext()) {
                // Get the array list for this iteration.
                var al3 : ArrayList = ArrayList(dictEnum.Value);
                // Access each element of the array.
                for (var j : int
 = 0; j < al3.Count; j++) {
                    // For the first element, retrieve the author names.
                    if (j == 0) {
                        // Get the metadata for the method.
                        var mInfo2 : MethodInfo = clsType.GetMethod(String(al3[j]));
                        // Retrieve the Authors attribute again.
                        var attr2 : Attribute = 
                                                      Attribute.GetCustomAttribute(mInfo2,
 
                                                                                
   AuthorsAttribute);
                        // Display the authors names.
                        if (attr2 != null)
                            Console.WriteLine("Authors: {0}, {1}", 
                                AuthorsAttribute(attr2).AuthorName1, 
                                                                AuthorsAttribute(attr2).AuthorName2);
                        else
                            Console.WriteLine("The authors could not be retrieved.");
                    }
                    // Display each method authored by this team.
                    Console.WriteLine(al3[j]);
                }
                Console.WriteLine("");
            }
        }
    }
}

/*
 *  Output:
 * Authors: Jean-Paul Sartre, Friedrich Nietzche
 * Method4
 * Method2
 * 
 * Authors: Immanuel Kant, Lao Tzu
 * Method3
 * Method1
 *
 * Authors: Immanuel Kant, Friedrich Nietzche
 * Method5
 */

HashCodeJS.DemoClass.Main();

プラットフォーム

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0
.NET Compact Framework
サポート対象 : 2.0、1.0

参照

関連項目
Attribute クラス
Attribute メンバ
System 名前空間