Question

在构造函数或类变量定义区域中创建List对象更好吗？他们最终会做同样的事情吗？什么时候一种方法优先于另一种？

以下是类定义的示例：

Public Class CProject

    'Variable to hold a list of Load Objects, Instantiate here vs in New().
    Private m_LoadList As New List(Of CLoad)

    Public Property LoadList() As List(Of CLoad)
        Get
            Return m_LoadList
        End Get
        Set(ByVal value As List(Of CLoad))
            m_LoadList = value
        End Set
    End Property

    Public Sub New()

    End Sub

End Class

节：

Public Class CProject

    'Variable to hold a list of Load Objects
    Private m_LoadList As List(Of CLoad)

    Public Property LoadList() As List(Of CLoad)
        Get
            Return m_LoadList
        End Get
        Set(ByVal value As List(Of CLoad))
            m_LoadList = value
        End Set
    End Property

    Public Sub New()
        m_LoadList = New List(Of CLoad)
    End Sub

 End Class

Answer 1

它更接近选项＃2，但有一些变化：

Private m_LoadList As List(Of ADR) = Nothing


Public Property LoadList() As List(Of CLoad)
    Get
        If m_LoadList Is Nothing Then
            m_LoadList = New List(Of CLoad)
        End If
        Return m_LoadList
    End Get
    Set(ByVal value As List(Of CLoad))
        m_LoadList = value
    End Set

End Property

通过这种方式，您可以引用该属性，并且仅在不存在时创建新实例。编码更简单，错误发生的可能性更小......

在构造函数或类变量定义区域中创建“新”对象更好吗？

1 个答案: