Compile a JApplet through another application

[Yohan Weerasinghe]

Hi,

I am writing a program and it has the functionality of compiling a JApplet which will be created in the same place where the original program locates. Anyway, it is not compiled, so I need to compile it when I click on the compile button. When the button is clicked, it will first find the location, and then compiles the file. Please have a look at the following sample code.

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import java.io.*;

public class CompileCheck extends JFrame implements ActionListener
{
    JButton but;
    
    
    public CompileCheck()
    {
        but = new JButton("Create");
        but.addActionListener(this);
        
        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new FlowLayout());
        buttonPanel.add(but);
        
        getContentPane().add(buttonPanel);
        
                
    }
    
    public void actionPerformed(ActionEvent ae)
    {
        createClassFile();
    }
    
    
    
     public void createClassFile()
    {
        File location = new File("");
        String locationString = "cd\t"+location.getAbsolutePath();
        
        System.out.println(locationString);
        System.out.println("javac appletTest.java");
    }
    
    public static void main(String[]args)
    {
        CompileCheck c = new CompileCheck();
        c.setVisible(true);
        c.setSize(200,200);
        c.validate();
    }
}

In here, the commands mentioned inside "System.out.println()" are just get printed, but the CMD do not identify them as commands, they are just "Strings" to it. How culd I make this application work? Please help...

[Rob Spoor]

Check out ProcessBuilder and When Runtime.exec() won't. You can make the latter a bit easier by calling redirectErrorStream(true) on the ProcessBuilder before creating the Process.

And beware of Concurrency in Swing - use a SwingWorker or EventQueue.invokeLater/SwingUtilities.invokeLater.

[Yohan Weerasinghe]

Thanks a lot for the reply Rob Spoor. I will check it, and will come and post with codes, so you can correct me if there is anything wrong. But please be informed that it may take 2 to 3 days because my grandmother is sick so all of we are gonna visit her at her place.

[Darryl Burke]

Thank you for keeping us posted, and best wishes for a speedy recovery for your grandmother.

[Yohan Weerasinghe]

Darryl Burke wrote:Thank you for keeping us posted, and best wishes for a speedy recovery for your grandmother.

Thanks Rob Spoor

[Yohan Weerasinghe]

Hi,

That link has information but no coded examples, so It was very difficult for me to understand the correct thing to do. Anyway, I tried the following to open CMD but no good. Please help

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import java.io.*;

public class CompileCheck extends JFrame implements ActionListener
{
    JButton but;
    
    
    public CompileCheck()
    {
        but = new JButton("Create");
        but.addActionListener(this);
        
        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new FlowLayout());
        buttonPanel.add(but);
        
        getContentPane().add(buttonPanel);
        
                
    }
    
    public void actionPerformed(ActionEvent ae)
    {
        try
        {
       ProcessBuilder p = new ProcessBuilder("cmd.exe","dir");
       p.start();
        }
        catch(Exception e)
        {
            JOptionPane.showMessageDialog(null,e);
        }
    }
    
    
    
     public void createClassFile()
    {
        File location = new File("");
        String locationString = "cd\t"+location.getAbsolutePath();
        
        System.out.println(locationString);
        System.out.println("javac appletTest.java");
    }
    
    public static void main(String[]args)
    {
        CompileCheck c = new CompileCheck();
        c.setVisible(true);
        c.setSize(200,200);
        c.validate();
    }
}

Anyway, I have seen in several places people opening CMD by Runtime.getRuntime(); . But I didn't use it because I don't know how to, and that class wasn't in the ProcessBuilder link. Please help me...

[Ulf Dittmer]

While you didn't say what "no good" means, I advise you not pursue this idea. You can't assume that a random applet client will have a compiler available - it might just have the JRE, not the JDK. Also keep in mind that this is functionality an applet is not allowed to perform without being signed.

[Yohan Weerasinghe]

Ulf Dittmer wrote:While you didn't say what "no good" means, I advise you not pursue this idea. You can't assume that a random applet client will have a compiler available - it might just have the JRE, not the JDK. Also keep in mind that this is functionality an applet is not allowed to perform without being signed.

This is the not working part..

 ProcessBuilder p = new ProcessBuilder("cmd.exe","dir");  
       p.start();  

It didn't do anything, no exceptions, no output, nothing!!

You can't assume that a random applet client will have a compiler available - it might just have the JRE, not the JDK.

No, actually this is a just a small code of testing. In the real program, my program will automatically generate the applet. But the case is, I can't let the generated applet to get compiled.. Please help...............

[Paul Clapham]

Yohan Weerasinghe wrote:This is the not working part..

 ProcessBuilder p = new ProcessBuilder("cmd.exe","dir");  
       p.start();  

It didn't do anything, no exceptions, no output, nothing!!

I was going to refer you to the "When Runtime Won't" article, but I see that Rob Spoor did that quite some time ago. If that's your code then evidently you haven't read and understood that article. I suggest you go back and do that.

[Yohan Weerasinghe]

Hi,

I found a way to do this

Process process = Runtime.getRuntime().exec("cmd.exe /c start");

Anyway not gonna use this until some one teach me what is happening here. I can understand what is cmd.exe is but what is "/c start" ???

[Paul Clapham]

Windows already provides help for their commands. So go to your Windows command line and type "Help cmd". And "Help Start".

[Yohan Weerasinghe]

Paul Clapham wrote:Windows already provides help for their commands. So go to your Windows command line and type "Help cmd". And "Help Start".

Thanks Paul, it helped a lot.

Now, after opening the CMD, I need that to operate the following commands automatically. Here they are,

1. cd\
2. cd java\appletTest
3. javac appletTest.java

How to do this? Please help me...

[Yohan Weerasinghe]

Darryl Burke wrote:Thank you for keeping us posted, and best wishes for a speedy recovery for your grandmother.

Thanks Darryl Burke

[Rob Spoor]

Both Runtime.exec and ProcessBuilder allow you to specify a working folder. This takes the place of the "CD" commands.

[Yohan Weerasinghe]

Rob Spoor wrote:Both Runtime.exec and ProcessBuilder allow you to specify a working folder. This takes the place of the "CD" commands.

Please, could you please give me a coded example?

[Rob Spoor]

Is it that hard to figure out the API? Runtime.exec has two overloaded versions that take a File. This File should be the folder to execute the command in. In your case that should be new File("\\java\\appletTest"). The envp argument can remain null.
ProcessBuilder has method directory that allows you to do the same.

[Yohan Weerasinghe]

Rob Spoor wrote:Is it that hard to figure out the API? Runtime.exec has two overloaded versions that take a File. This File should be the folder to execute the command in. In your case that should be new File("\\java\\appletTest"). The envp argument can remain null.
ProcessBuilder has method directory that allows you to do the same.

Great!!! Manged it. Here is the new code

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import java.io.*;

public class CompileCheck extends JFrame implements ActionListener
{
    JButton but;
    
    
    public CompileCheck()
    {
        but = new JButton("Create");
        but.addActionListener(this);
        
        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new FlowLayout());
        buttonPanel.add(but);
        
        getContentPane().add(buttonPanel);
        
                
    }
    
    public void actionPerformed(ActionEvent ae)
    {
        createClassFile();
    }
    
    
    
     public void createClassFile()
    {
        File location = new File("");
        String locationString = location.getAbsolutePath();
        
        
        try
        {
            Process p = Runtime.getRuntime().exec("cmd.exe /c start", null, new File(locationString));
            
           
            
           
        }
        catch(Exception e)
        {
            JOptionPane.showMessageDialog(null,e);
        }
    }
    
    public static void main(String[]args)
    {
        CompileCheck c = new CompileCheck();
        c.setVisible(true);
        c.setSize(200,200);
        c.validate();
    }
}

Now I must execute those "javac appletTest.java" command. Will try and post back

[Yohan Weerasinghe]

Thanks all of you for the help.. I managed to do it with this

Process p = Runtime.getRuntime().exec("javac \"C:/java/appletTest/appletTest.java\"");

I know I can't apply this kind of code everywhere, but for this purpose, this is what I need. Now I am gonna jump to the tutorial "When Runtime.exec() won't" to check a cored which I can apply everywhere.. I printed that whole article