How to put the ".class" file in Memory with Javac?

The J2SE 6 RC have an tool : javax.tools.JavaComplier. I can use it to compile the source code in memory( I implemented an JavaFileObject).
But the compiler aways put the output file(.class) to file system. It;s not my want to do . I am writing an IDE ,I use javac to determine the code error after the user's typing. So complier is used a lot , writing to file system is a time consuming job.
I also want to use the byte code(".class" file) for reflection , so if the JavaCompiler can put the output file in memory and then I can reflect it.
My current solution is puting the output file to file system then use Class.forName() to reload it in memory then reflect it. It seems a useless IO operation with file system.
How can I do with it?
Thanks!

Those 'useless' I/O operations are one or two out of thousands that are implied by compiling a Java source file.
I wouldn't worry about it.

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Hi
Just for completeness, what version of VB.NET are you using?
Here is a complete project to copy all the files with the added "ABL," at the start of each line. You need to start a new Project with a BLANK default Form1, and replace all of Form1 code with the code below. When you run this project, you
need to use the 2 buttons to set up the ORIGINAL file folder and a folder to place the copies. You need to check if the file EXTENSION is correct (I assumed txt), and check the text to add to each line is correct. Once all is set up you should have a
big red button to start the operation.
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' new project with default BLANK Form1
' replace all Form1 code with this code
' WARNING: make sure you have a backup of
' any files you use this application to
' operate on.
Option Strict On
Option Infer Off
Option Explicit On
Public Class Form1
Dim OrigFileFolderPath As String = Nothing
Dim CopyToFolderPath As String = Nothing
Dim lab1, lab2, lab3 As New Label
Dim tb1, tb2, tb3 As New TextBox
Dim b1, b2, b3, b4 As New Button
Dim fb As New FolderBrowserDialog
Dim bgw As New System.ComponentModel.BackgroundWorker
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
Me.Size = New Size(731, 300)
With lab1
.Text = "Original Files Folder Path"
.Location = New Point(15, 5)
End With
With tb1
.Width = 560
.Location = New Point(10, 30)
.BackColor = Color.Khaki
.ForeColor = Color.Maroon
.Font = New Font(Me.Font.FontFamily, 12)
.BorderStyle = BorderStyle.FixedSingle
.Anchor = AnchorStyles.Top Or AnchorStyles.Left Or AnchorStyles.Right
End With
With lab2
.Text = "Copy Files to Folder Path"
.Location = New Point(15, 125)
End With
With tb2
.Width = 665
.Location = New Point(10, 150)
.BackColor = Color.Khaki
.ForeColor = Color.Maroon
.Font = New Font(Me.Font.FontFamily, 12)
.BorderStyle = BorderStyle.FixedSingle
.Anchor = AnchorStyles.Top Or AnchorStyles.Left Or AnchorStyles.Right
End With
With lab3
.Text = "File Ext"
.Location = New Point(600, 5)
.Anchor = AnchorStyles.Top Or AnchorStyles.Right
End With
With tb3
.Text = ".txt"
.Width = 80
.Location = New Point(590, 30)
.BackColor = Color.Khaki
.ForeColor = Color.Maroon
.TextAlign = HorizontalAlignment.Center
.Font = New Font(Me.Font.FontFamily, 12)
.BorderStyle = BorderStyle.FixedSingle
.Anchor = AnchorStyles.Top Or AnchorStyles.Right
End With
With b1
.Text = "Choose Original Files Folder Path"
.AutoSize = True
.Location = New Point(10, 65)
End With
With b2
.Text = "Choose Copy Files to Folder Path"
.AutoSize = True
.Location = New Point(10, 185)
End With
With b3
.Text = "DO THE COPY"
.AutoSize = False
.Size = New Size(240, 50)
.BackColor = Color.Red
.ForeColor = Color.White
.Font = New Font(Me.Font.FontFamily, 20, FontStyle.Bold)
.Location = New Point(420, 80)
.Anchor = AnchorStyles.Top Or AnchorStyles.Right
.Visible = False
End With
With b4
.Text = "CANCEL JOB"
.AutoSize = False
.Size = New Size(240, 50)
.BackColor = Color.Red
.ForeColor = Color.White
.Font = New Font(Me.Font.FontFamily, 20, FontStyle.Bold)
.Location = New Point(420, 80)
.Anchor = AnchorStyles.Top Or AnchorStyles.Right
.Visible = False
End With
Me.Controls.AddRange({lab1, lab2, lab3, tb1, tb2, tb3, b1, b2, b3, b4})
With bgw
.WorkerReportsProgress = True
.WorkerSupportsCancellation = True
End With
AddHandler bgw.DoWork, AddressOf bgw_DoWork
AddHandler bgw.RunWorkerCompleted, AddressOf bgw_Completed
AddHandler b1.Click, AddressOf b1_Click
AddHandler b2.Click, AddressOf b2_Click
AddHandler b3.Click, AddressOf b3_Click
AddHandler b4.Click, AddressOf b4_Click
End Sub
Private Sub b1_Click(sender As Object, e As EventArgs)
fb.SelectedPath = My.Computer.FileSystem.SpecialDirectories.MyDocuments
fb.ShowNewFolderButton = False
Dim r As DialogResult = fb.ShowDialog
If r = Windows.Forms.DialogResult.OK Then
tb1.Text = fb.SelectedPath
If IO.Directory.Exists(tb1.Text) AndAlso IO.Directory.Exists(tb2.Text) AndAlso Not (tb1.Text = tb2.Text) Then
If tb3.Text = Nothing Then
redo: tb3.Text = InputBox("Enter the file extension that you want to copy/change", "FILE EXTENSION")
If tb3.Text = Nothing Then GoTo redo
End If
b3.Visible = True
Else
b3.Visible = False
End If
End If
End Sub
Private Sub b2_Click(sender As Object, e As EventArgs)
fb.SelectedPath = My.Computer.FileSystem.SpecialDirectories.MyDocuments
fb.ShowNewFolderButton = True
Dim r As DialogResult = fb.ShowDialog
If r = Windows.Forms.DialogResult.OK Then
tb2.Text = fb.SelectedPath
If IO.Directory.Exists(tb1.Text) AndAlso IO.Directory.Exists(tb2.Text) AndAlso Not (tb1.Text = tb2.Text) Then
If tb3.Text = Nothing Then
redo: tb3.Text = InputBox("Enter the file extension that you want to copy/change", "FILE EXTENSION")
If tb3.Text = Nothing Then GoTo redo
End If
b3.Visible = True
Else
b3.Visible = False
End If
End If
End Sub
Private Sub b3_Click(sender As Object, e As EventArgs)
b3.Visible = False
b4.Visible = True
If Not tb3.Text.StartsWith(".") Then tb3.Text = "." & tb3.Text
bgw.RunWorkerAsync()
End Sub
Private Sub b4_Click(sender As Object, e As EventArgs)
bgw.CancelAsync()
End Sub
Private Sub ReadPWFile(fn As String)
Dim filename As String = My.Computer.FileSystem.GetName(fn)
Dim barename As String = IO.Path.GetFileNameWithoutExtension(fn)
Dim copyto As String = tb2.Text & "\" & filename
Dim line As String = Nothing
Dim lines As New List(Of String)
Using sr As IO.StreamReader = New IO.StreamReader(fn)
Do
line = sr.ReadLine()
If Not line = Nothing Then
lines.Add(barename & "," & line)
End If
Loop Until line = Nothing
End Using
Using sw As IO.StreamWriter = New IO.StreamWriter(copyto)
For Each s As String In lines
sw.WriteLine(s)
Next
End Using
End Sub
Private Sub bgw_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs)
Dim ftc As Collections.ObjectModel.ReadOnlyCollection(Of String) = My.Computer.FileSystem.GetFiles(tb1.Text)
For Each f As String In ftc
If bgw.CancellationPending Then
e.Cancel = True
Exit For
End If
Dim ex As String = My.Computer.FileSystem.GetFileInfo(f).Extension.ToLower
If My.Computer.FileSystem.GetFileInfo(f).Extension.ToLower = tb3.Text.ToLower Then
ReadPWFile(f)
End If
Next
End Sub
Public Sub bgw_Completed(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs)
tb1.Text = Nothing
tb2.Text = Nothing
b3.Visible = False
b4.Visible = False
MessageBox.Show("Finished copying files", "Job Completed")
End Sub
End Class
Regards Les, Livingston, Scotland

How to put the ".class" file in Memory with Javac?

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