Question

我刚刚开始学习颤振，我很好奇我如何00 00 00 00动态地颤动

在setState()中，我通常动态地使用如下函数来React Native：

setState

class foo extends React.Component{ state={ username:null, password:null } toggleSetState(whatState, value){ this.setState({ [whatState]: value }) } render() { return ( <View> <TextInput value={this.state.username} onChangeText={(text)=>{toggleSetState(username, text)} /> <TextInput value={this.state.password} onChangeText={(text)=>{toggleSetState(password, text)} /> </View> ); } }中的上述代码等效于什么？

我在Flutter中尝试过此方法，但似乎不起作用

Flutter

Answer 1

setState(() { _myState = newValue });

_myState为变量

Answer 2

您只需要创建一个变量来保存值。我很困惑为什么不修改短暂状态时调用setState

以下是一些有用的文档 https://flutter.dev/docs/development/data-and-backend/state-mgmt/ephemeral-vs-app

 Lat Pulldowns
 Squats
 Lat Pulldowns
 Squats
 Reverse Lunges

Answer 3

经过研究和尝试，我可以使用以下代码实现我想要的：

Option Explicit

Private Sub Worksheet_Change(ByVal Target As Range)

    Dim BarCode As String
    Dim LastRowA As Long, LastRowC As Long, i As Long, Times As Long
    Dim arr As Variant

    'Let us assume that:
    '1. All bar codes appears in column A
    '2. The Selected bar code are in cell B2
    '3. And the results are in column C

    With ThisWorkbook.Worksheets("Sheet1")

        If Not Intersect(Target, .Range("B2")) Is Nothing And Target.Count = 1 Then '<- Check if there is any change in cell B2

            LastRowC = .Cells(.Rows.Count, "C").End(xlUp).Row

            Application.EnableEvents = False

                If LastRowC > 1 Then

                    .Range("C2:C" & LastRowC).Clear '<- If there are data in the results field clear them

                End If

                BarCode = Target.Value '<- Get the code imported

                LastRowA = .Cells(.Rows.Count, "A").End(xlUp).Row

                arr = .Range("A2:A" & LastRowA) '<- Create an array with all the bar codes

                For i = LBound(arr) To UBound(arr) '<- Loop codes
                    Debug.Print arr(i, 1)
                    If arr(i, 1) = BarCode Then
                        Times = Times + 1
                        If Times > 1 Then
                            LastRowC = .Cells(.Rows.Count, "C").End(xlUp).Row
                            .Range("C" & LastRowC + 1).Value = arr(i, 1)
                        End If
                    Else
                        LastRowC = .Cells(.Rows.Count, "C").End(xlUp).Row
                        .Range("C" & LastRowC + 1).Value = arr(i, 1)
                    End If

            Next i

            Application.EnableEvents = True

        End If

    End With

End Sub

如何在flutter中动态设置状态变量？

3 个答案: