注意！
重载GetInstance或设置颜色不是我的想法.颜色应仅设置一次.我想确保MyPainter仅使用初始化颜色进行绘制.应该使用任何默认颜色.

为了更清楚,我提供了一个示例：

''' <summary>
''' Singleton class MyPainter
''' </summary>
Public Class MyPainter
  Private Shared _pen As Pen
  Private Shared _instance As MyPainter = Nothing

  Private Sub New()
  End Sub

  ''' <summary>
  ''' This method should be called only once,like a constructor!
  ''' </summary>
  Public Shared Sub InitializeMyPainter(ByVal defaultPenColor As Color)
    _pen = New Pen(defaultPenColor)
  End Sub


  Public Shared Function GetInstance() As MyPainter
    If _instance Is Nothing Then
      _instance = New MyPainter
    End If

    Return _instance
  End Function

  Public Sub DrawLine(ByVal g As Graphics,ByVal pointA As Point,ByVal pointB As Point)
    g.DrawLine(_pen,pointA,pointB)
  End Sub

End Class

谢谢.