vb System.Object.GetHashCode类(方法)实例源码

Public Structure Number
   Private n As Integer

   Public Sub New(value As Integer)
      n = value
   End Sub

   Public ReadOnly Property Value As Integer
      Get
         Return n
      End Get
   End Property
   
   Public Overrides Function Equals(obj As Object) As Boolean
      If obj Is Nothing OrElse Not TypeOf obj Is Number Then
         Return False
      Else
         Return n = CType(obj, Number).n
      End If
   End Function      
   
   Public Overrides Function GetHashCode() As Integer
      Return n
   End Function
   
   Public Overrides Function ToString() As String
      Return n.ToString()
   End Function
End Structure

Module Example
   Public Sub Main()
      Dim rnd As New Random()
      For ctr As Integer = 0 To 9
         Dim randomN As Integer = rnd.Next(Int32.MinValue, Int32.MaxValue)
         Dim n As New Number(randomN)
         Console.WriteLine("n = {0,12}, hash code = {1,12}", n, n.GetHashCode())
      Next
   End Sub
End Module

' A type that represents a 2-D point.
Public Structure Point
    Private x As Integer
    Private y As Integer

    Public Sub New(x As Integer, y As Integer)
       Me.x = x
       Me.y = y
    End Sub
    
    Public Overrides Function Equals(obj As Object) As Boolean
       If Not TypeOf obj Is Point Then Return False
       
       Dim p As Point = CType(obj, Point)
       Return x = p.x And y = p.y
    End Function
    
    Public Overrides Function GetHashCode() As Integer 
        Return x Xor y
    End Function 
End Structure 

Public Module Example
   Public Sub Main() 
      Dim pt As New Point(5, 8)
      Console.WriteLine(pt.GetHashCode())
        
      pt = New Point(8, 5)
      Console.WriteLine(pt.GetHashCode())
   End Sub 
End Module

Public Structure Point
    Private x As Integer
    Private y As Integer

    Public Sub New(x As Integer, y As Integer)
       Me.x = x
       Me.y = y
    End Sub
    
    Public Overrides Function Equals(obj As Object) As Boolean
       If Not TypeOf obj Is Point Then Return False
       
       Dim p As Point = CType(obj, Point)
       Return x = p.x And y = p.y
    End Function
    
    Public Overrides Function GetHashCode() As Integer 
        Return Tuple.Create(x, y).GetHashCode()
    End Function 
End Structure 

Public Module Example
    Public Sub Main() 
        Dim pt As New Point(5, 8)
        Console.WriteLine(pt.GetHashCode())
        
        pt = New Point(8, 5)
        Console.WriteLine(pt.GetHashCode())
    End Sub 
End Module

Public Function ShiftAndWrap(value As Integer, positions As Integer) As Integer
   positions = positions And &h1F
   
   ' Save the existing bit pattern, but interpret it as an unsigned integer.
   Dim number As UInteger = BitConverter.ToUInt32(BitConverter.GetBytes(value), 0)
   ' Preserve the bits to be discarded.
   Dim wrapped AS UInteger = number >> (32 - positions)
   ' Shift and wrap the discarded bits.
   Return BitConverter.ToInt32(BitConverter.GetBytes((number << positions) Or wrapped), 0)
End Function

Public Structure Point
    Private x As Integer
    Private y As Integer

    Public Sub New(x As Integer, y As Integer)
       Me.x = x
       Me.y = y
    End Sub
    
    Public Overrides Function Equals(obj As Object) As Boolean
       If Not TypeOf obj Is Point Then Return False
       
       Dim p As Point = CType(obj, Point)
       Return x = p.x And y = p.y
    End Function
    
    Public Overrides Function GetHashCode() As Integer 
        Return ShiftAndWrap(x.GetHashCode(), 2) XOr y.GetHashCode()
    End Function 
    
    Private Function ShiftAndWrap(value As Integer, positions As Integer) As Integer
        positions = positions And &h1F
      
        ' Save the existing bit pattern, but interpret it as an unsigned integer.
        Dim number As UInteger = BitConverter.ToUInt32(BitConverter.GetBytes(value), 0)
        ' Preserve the bits to be discarded.
        Dim wrapped AS UInteger = number >> (32 - positions)
        ' Shift and wrap the discarded bits.
        Return BitConverter.ToInt32(BitConverter.GetBytes((number << positions) Or wrapped), 0)
    End Function
End Structure 

Module Example
   Public Sub Main()
        Dim pt As New Point(5, 8)
        Console.WriteLine(pt.GetHashCode())
        
        pt = New Point(8, 5)
        Console.WriteLine(pt.GetHashCode())
   End Sub
End Module