Android Code Snippet Edittext verify input

Using edittext.setError() and Regex we can verify the input of the user in an edittext box, by identifying the pattern of the input text
and setting the error flag or discoloring the text whenever it did not comply to the required rule as email and currency. In the same way
as in the example we can impose the rule of the input, e.g., a date or a phone number.

#Region  Project Attributes
    #ApplicationLabel: B4A Example
    #VersionCode: 1
    #VersionName:
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: unspecified
    #CanInstallToExternalStorage: False
#End Region

#Region  Activity Attributes
    #FullScreen: False
    #IncludeTitle: True
#End Region

Sub Process_Globals
        Private xui As XUI
End Sub

Sub Globals
    
    Private edtMail As EditText
    Private edtPrice As EditText
    
    Private Label2 As Label
    Private Label1 As Label
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    edtMail.Initialize("edtMail")
    Activity.AddView(edtMail, 30dip, 10%y, 90%x, 50dip)
    edtMail.As(JavaObject).RunMethod("setError",Array("Enter valid email"))
    edtMail.As(B4XView).SetColorAndBorder(Colors.Transparent,1dip, Colors.Black, 5dip)
    
    edtPrice.Initialize("edtPrice")
    Activity.AddView(edtPrice, 30dip, 26%y, 90%x, 50dip)
    edtPrice.As(JavaObject).RunMethod("setError",Array("Enter valid currency value"))
    edtPrice.As(B4XView).SetColorAndBorder(Colors.Transparent,1dip, Colors.Black, 5dip)
End Sub

Sub edtMail_TextChanged (Old As String, New As String)
    ValidateEmail(New)
End Sub
Sub edtPrice_TextChanged (Old As String, New As String)
    ValidatePrice(New)
End Sub
Sub ValidateEmail(Text As String)
    
    Dim EmailPattern As String = "^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,6}$"
    
    ' Check if empty - clear error if empty
    If Text.Trim.Length = 0 Then
        edtMail.As(JavaObject).RunMethod("setError", Array(Null))
        Return
    End If
    
    ' Check if matches pattern
    Dim matcher As Matcher
    matcher = Regex.Matcher(EmailPattern, Text)
    
    If matcher.Find Then
        edtMail.TextColor=Colors.Black
        edtMail.As(JavaObject).RunMethod("setError", Array(Null))
    Else
        ' Invalid email - show error
        edtMail.TextColor=Colors.Red
        edtMail.As(JavaObject).RunMethod("setError", Array("Enter valid email, e.g., [email protected]"))
    End If
End Sub
Sub ValidatePrice(Text As String)
    Dim PricePattern As String = "^\$?\d{1,3}(,\d{3})*(\.\d{2})?$|^\$?\d+(\.\d{2})?$"
    
    If Text.Trim.Length = 0 Then
        edtPrice.As(JavaObject).RunMethod("setError", Array(Null))
            Return
    End If
    
    Dim matcher As Matcher
    matcher = Regex.Matcher(PricePattern, Text)
    
    If matcher.Find Then
        edtPrice.TextColor=Colors.Black
        edtPrice.As(JavaObject).RunMethod("setError", Array(Null))
    
    Else
        edtPrice.TextColor=Colors.Red
        edtPrice.As(JavaObject).RunMethod("setError", Array("Enter valid currency value (e.g., $35.00)"))
    End If
End Sub


Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub