使用VB.net使用“新关键字"添加到数组 [英] Adding to an array using the New Keyword using VB.net

问题描述

我的班级设置如下:

I have a class set up as follows:

Public Class Tags

    Public Sub New()

    End Sub

    Public Sub New(ByVal sTagName As String, _
                   ByVal sTagValue As String)

        _tagName = sTagName
        _tagValue = sTagValue

    End Sub

    Private _tagName As String
    Public ReadOnly Property TagName() As String

        Get
            Return _tagName
        End Get

    End Property

    Private _tagValue As String
    Public ReadOnly Property TagValue() As String

        Get
            Return _tagValue
        End Get

    End Property

End Class

我有一个调用的函数，该函数将加载标签数组.

到目前为止，我是这个

I have a function I call that will load an array of Tags.

What I have so far is this

Public Class WMAID3Tag.vb

    dim aryOfTags as Tags()

    public function GetTags(ByVal fn as String) as Tags()

        ' Do some stuff to get a tagName and tagValue
        aryOfTags = New Tags() {New Tags(tagName, tagValue)

        ' Look for more tags
        aryOfTags = New Tags() {New Tags(tagName, tagValue)

        ' Found all the tags there are
        Return aryOfTags

    End Function

End Class

我遇到的问题是aryOfTags永远不会超过1个元素.

The problem I am having is that aryOfTags never grows beyond 1 element. Each new tag found simply replaces the last.

推荐答案

原因是在Function
中

The reason is that in the Function

public function GetTags(ByVal fn as String) as Tags()

    ' Do some stuff to get a tagName and tagValue
    aryOfTags = New Tags() {New Tags(tagName, tagValue)

    ' Look for more tags
    aryOfTags = New Tags() {New Tags(tagName, tagValue)

    ' Found all the tags there are
    Return aryOfTags

End Function

在寻找更多标签下，为aryOfTags分配了一个新的标签数组，该数组替换了第一步中已分配的标签数组.因此，只有aryOfTags仅包含第二步中分配的一个元素.
两个返回两个标签，可以进行以下修改.

Under Look for more tags, An new array of tags is assigned to aryOfTags, which replaces the array of tags already assigned under the first step. So, only aryOfTags contains only one element assigned in the second step.
Two return two tags, the following modification can be done.

Public Class WMAID3Tag.vb

    dim aryOfTags(1) as Tags

    public function GetTags(ByVal fn as String) as Tags()

        ' Do some stuff to get a tagName and tagValue
        aryOfTags(0) = New Tags(tagName, tagValue)

        ' Look for more tags
        aryOfTags(1) = New Tags(tagName, tagValue)

        ' Found all the tags there are
        Return aryOfTags

    End Function
End Class

但是，最好使用List动态分配元素数量，而无需先定义大小.在上面的函数中，数组的大小声明为2号.如果期望更多，则将相应地确定大小.
使用List的功能如下

However, it is preferable to use List to dynamically assign number of elements without first defining the size. In the above function the size of array is declared as 2 Nos. If more are expected, then size shall be fixed accordingly.
The function using List is as follows

public function GetTagsList(ByVal fn as String) as List(Of Tags)
    dim listOfTags as new List(Of Tags)
    ' Do some stuff to get a tagName and tagValue
    listOfTags.Add(New Tags("tag1", "value1"))

    ' Look for more tags
    listOfTags.Add(New Tags("tag2", "value2"))
    listOfTags.Add(New Tags("tag3", "value3"))

    ' Found all the tags there are
    Return listOfTags

End Function

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