How to convert string to timespan ? visual basic, stopwatch, lap system - vb.net

Question

I am a beginer and making a stopwatch with lap feature using visual studio 2012, visual basic. Now I stuck in the lap feature. In the lap feature I want to display the result using listview ...
When the user click the lap button 2nd times it has to show the lap time between first click and 2nd click.. but i m not getting the result. Is here anybody to resolve my problem ? thank u in advance
here is the code of lap button event
Private Sub btnLap_Click(sender As Object, e As EventArgs) Handles btnLap.Click
Dim lap As String = (sw.Elapsed.Hours.ToString("00") & ":" & sw.Elapsed.Minutes.ToString("00") & _
":" & sw.Elapsed.Seconds.ToString("00") & ":" & sw.Elapsed.Milliseconds.ToString("00"))
lapcount += 1
Dim i As Integer = ListView1.Items.Count
If i <= 0 Then
ListView1.Items.Add(CStr(lapcount), i)
ListView1.Items(i).SubItems.Add(lap)
ListView1.Items(i).SubItems.Add(lap)
Else
ListView1.Items.Add(CStr(lapcount), i)
ListView1.Items(i).SubItems.Add(lap)
ListView1.Items(i).SubItems.Add((TimeSpan.parse(lap)- Timespan.parse(lastlap)).ToString) ''' I can't subtract the value from 2nd click to first click
End If
lastlap = (ListView1.Items(i).SubItems(1).ToString)
End Sub

Answer 1

To be honest, its usually a bad idea to use UI objects as your primary store of data. You would be much better storing the split times in a List (Of TimeSpan) and calculating calculating the lap times from that.
In my sample I declared some class objects so that the code would run. You could adapt these as necessary.
Dim sw As New Stopwatch
Dim lapcount As Integer = 1
Dim lastlap As Integer
Dim lapintervals As New List(Of TimeSpan)
Dim timeFormat As String = "hh\:mm\:ss\.fff"
So in your button click event you would have something like this ..
Private Sub BtnLap_Click(sender As Object, e As EventArgs) Handles BtnLap.Click
Dim ts As TimeSpan = sw.Elapsed
lapintervals.Add(ts)
AddTimeToListView(lapintervals.Count, lapintervals.Last)
lapcount += 1
End Sub
And you would add the info to your ListView like this
Private Sub AddTimeToListView(lapcount As Integer, lapsplit As TimeSpan)
Dim lvItem As New ListViewItem(lapcount.ToString, lapcount)
If lapcount = 1 Then
lvItem.SubItems.Add(lapsplit.ToString(timeFormat))
lvItem.SubItems.Add(lapsplit.ToString(timeFormat))
Else
lvItem.SubItems.Add(lapsplit.ToString(timeFormat))
lvItem.SubItems.Add((lapsplit.Subtract(lapintervals(lapcount - 2))).ToString(timeFormat))
End If
ListView1.Items.Add(lvItem)
End Sub

Answer 2

thenk you very much for answering...
finally i have finished my stopwatch application ..
i've made this and my leader gave me 8 out of 10 .. it pretty much good for me
here is the design form and code
visual basic 2012, stopwatch with lap button
enter image description here
[code]
Public Class Stopwatch
Public watch As Form 'スタートページから呼び出すため
Dim sw As New System.Diagnostics.Stopwatch()
Dim lapcount As Integer
Dim lastlap As String
'スタート・ストップボタン
Private Sub btnStart_Click(sender As Object, e As EventArgs) Handles btnStart.Click
If btnStart.Text = "Start" Then
sw.Start() '時間計測開始
Timer1.Interval = 10
Timer1.Enabled = True
btnStart.Text = "Stop"
Else
sw.Stop() '時間計測一時停止
Timer1.Enabled = False
btnStart.Text = "Start"
End If
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
lblTime.Text = sw.Elapsed.ToString("hh\:mm\:ss\:ff")
End Sub
'cancel / reset ボタン
Private Sub btnReset_Click(sender As Object, e As EventArgs) Handles btnReset.Click
sw.Reset() '初期状態にする
Timer1.Enabled = False
lblTime.Text = "00:00:00:00"
ListView1.Items.Clear()
btnStart.Text = "Start"
lapcount = 0
End Sub
'ラップボタン
Private Sub btnLap_Click(sender As Object, e As EventArgs) Handles btnLap.Click
Dim lap = sw.Elapsed.ToString("hh\:mm\:ss\:fff") ' ラップ時間を変数に代入
lapcount += 1
Dim i As Integer = ListView1.Items.Count
If i <= 0 Then ' ＬｉｓｔｖｉｅｗのアイテムのＶａｌｕｅが０または０より小さければ
ListView1.Items.Add(CStr(lapcount), i)
ListView1.Items(i).SubItems.Add(lap) 'アイテムとサブアイテム表示
ListView1.Items(i).SubItems.Add(lap)
Else '文字列となっている結果時間を整数型に変換する/　// ラップ経過時間を取得するため
Dim day As Integer = 0
Dim hr As Integer = CInt(Strings.Left(lap, 2))
Dim min As Integer = CInt(Strings.Mid(lap, 4, 2))
Dim sec As Integer = CInt(Strings.Mid(lap, 7, 2))
Dim milli As Integer = CInt(Strings.Mid(lap, 10, 3))
Dim dayy As Integer = 0
Dim hrr As Integer = CInt(Strings.Mid(lastlap, 19, 2))
Dim minn As Integer = CInt(Strings.Mid(lastlap, 22, 2))
Dim secc As Integer = CInt(Strings.Mid(lastlap, 25, 2))
Dim millii As Integer = CInt(Strings.Mid(lastlap, 28, 3))
'現在のラップ時間に直前に記憶したラップ時間を引き、1回目から2回目のラップボタン押下までの経過時間を図る
Dim answer = createtimespan(day, hr, min, sec, milli) - createtimespan(dayy, hrr, minn, secc, millii)
Dim ansTS = answer.ToString("hh\:mm\:ss\:fff") 'ミリ秒3桁まで表示するように指定
ListView1.Items.Add(CStr(lapcount), i)
ListView1.Items(i).SubItems.Add(lap)
ListView1.Items(i).SubItems.Add((ansTS).ToString) 'ラップ時間の表示
End If
lastlap = ListView1.Items(i).SubItems(1).ToString '直前のラップタイムを記憶
End Sub
Private Function createtimespan(ByVal days As Integer, ByVal hours As Integer, ByVal minutes As Integer, _
ByVal seconds As Integer, ByVal milliseconds As Integer) As TimeSpan
Dim elapsedTime As New TimeSpan(days, hours, minutes, seconds, milliseconds)
Return (elapsedTime)
End Function
End Class