B4J Question Find files filled with zeros

Sub Process_Globals
 Dim flist As List
 Dim NotZero As Boolean
End Sub
Sub AppStart (Args() As String)
 flist.Initialize
 flist.AddAll(File.ListFiles("c:/temp"))
 For Each filename As String In flist
 checkforzeros("C:/temp/"&filename) 
 Next
End Sub
Sub checkforzeros(s As String)
 If File.IsDirectory("",s) Then Return ' ignore directories
 Dim in As InputStream
 Dim flen As Int
 in = File.OpenInput("",s)
 Dim buf(in.BytesAvailable) As Byte
 NotZero = False
 flen = in.ReadBytes(buf,0,in.BytesAvailable) ' read the file
 For a = 0 To flen-1  ' check each byte for 0x00 - exit on first non x00 as file is not just 0x00
 If buf(a)<> 0x00 Then 
 NotZero = True
 Exit
 End If
 Next
 If Not(NotZero) Then Log(s&" is zero file and needs replacing")' is zero file you would copy backup to replace it after in.close
  in.close  ' close input stream
' if Not(NotZero) then DoYourBackupCopyHere()
End Sub
'Return true to allow the default exceptions handler to handle the uncaught exception.
Sub Application_Error (Error As Exception, StackTrace As String) As Boolean
 Return True
End Sub