Question on Exceptions

[yelllow4u]

OK, I have a quick question on exceptions.

This basically has to do with system calls. Let's say I run a command from the command line (like DOS on XP). This can be any command it doesn't matter. For an example let's say I open up the command line and type 'xcopy'. Without any parameters I get an error that says 'Invalid number of parameters'. Now lets take this a step further and put the command inside a Java application and make it a system call. How do I know what kind of exception this is? Would this be an application exception since it is coming from the xcopy program from within the command prompt? Is there something that I can put in my code that tells me exactly what kind of exception is going on?

I have some code I can post if everyone needs a solid example. I am probably making this harder than it needs to be...

[Seemster]

The native command (such as xcopy) should return a value once executed. You can check that value to determine if an error occurred.

[yelllow4u]

Ok...next dumb question....how do I check a value that xcopy kicks back to see if its and error or not. Now I have a swing GUI with some text boxes and an execute button and if I leave the text boxes blank and click the execute button I can get an IO exception to pop up, but I'm not sure how to get errors that come from xcopy itself to pop up.



Here is some of the code I have...

try {
p = Runtime.getRuntime().exec(command, null, filepath);
} catch (IOException ex) {
JOptionPane.showMessageDialog(null,
"Cannot Copy: " + ex.getMessage(), "Error", JOptionPane.WARNING_MESSAGE);
return;
}

[Seemster]

The Process object has an exitValue() method. Try that.

exitValue()
Returns the exit value for the subprocess.

[yelllow4u]

OK....I been doing some reading on the exitValue() method and it looks like it throws an IllegalThreadStateException. Is it possible to print the exitValue() value so that I can write code to handle any number thats not zero? I tried to print the value in the code below, but the IllegalThreadStateException is thrown and my value is never printed.

Here is the code I have:

Code:

  private void btn_RenameActionPerformed(java.awt.event.ActionEvent evt) {                                           
// TODO add your handling code here:
     String VOBpath = txt_VOBpath.getText();
     String CReplica = txt_Currentrepname.getText();
     String NReplica = txt_Newrepname.getText();
     String command = ("cmd /c multitool rename replica:" + CReplica + " "+ NReplica);
     
     File filepath = new File(VOBpath);
     Process p = null;
        try {
            p = Runtime.getRuntime().exec(command, null, filepath);
           int exitVal = p.exitValue();
           System.out.println("Process exitValue: " + exitVal);
        } catch (IOException ex) {
            JOptionPane.showMessageDialog(null,
              "Cannot Rename Replica: " + ex.getMessage(), "Error", JOptionPane.WARNING_MESSAGE);
            return;
        } catch (IllegalThreadStateException I) {
                return;
        }
    }

Can I use 'if' statements inside my catch (IllegalThreadStateException I) to deal with the various exitValue's?

Something like....

Code:

catch (IllegalThreadStateException I) {
    if (exitVal = 1){
        // Do something
      }
    if (exitVal = 2){
       // Do something
     }
  }

[yelllow4u]

Update....OK, I am on to something. I have some working code, but what would I need to change to print out the error that is printed on the DOS screen? I determined that when the exitValue is 1 and error has occured....so I throw and exception and cath it. But when I print the error to a message box it just says "null". How do I get the error that is printed in the DOS screen to apear word for word in a message box? Below is what I have so far;-)

Code:

    private void btn_RenameActionPerformed(java.awt.event.ActionEvent evt) {                                           
// TODO add your handling code here:
     String VOBpath = txt_VOBpath.getText();
     String CReplica = txt_Currentrepname.getText();
     String NReplica = txt_Newrepname.getText();
     String command = ("cmd /c multitool rename replica:" + CReplica + " "+ NReplica);
     
     File filepath = new File(VOBpath);
     Process p = null;
        try {
           p = Runtime.getRuntime().exec(command, null, filepath);
           int exitVal = p.waitFor();
           System.out.println("Process exitValue: " + exitVal);
           if(exitVal == 1){
               throw ( new Throwable()); 
           }
        } catch (IOException ex) {
            JOptionPane.showMessageDialog(null,
              "Cannot Rename Replica: " + ex.getMessage(), "Error", JOptionPane.WARNING_MESSAGE);
            return;
        } catch (InterruptedException in){
            JOptionPane.showMessageDialog(null,
              "Cannot Rename Replica: " + in.getMessage(), "Error", JOptionPane.WARNING_MESSAGE);
            return;
        } catch (Throwable T){
            JOptionPane.showMessageDialog(null,
              "Cannot Rename Replica: " + T.getMessage(), "Error", JOptionPane.WARNING_MESSAGE);
            return;
        }
    }

[yelllow4u]

So I was thinking maybe I need to use one of the readers and read the output stream? If I run a command from a DOS prompt and it kicks back a response (let's say an error) that response can be read using getOutputStream correct? Or do I need to use getInputStream?

I tried something like below and all it does is print junk and not what I would expect. I just want the DOS error to be printed if it is detected.

Code:

 private void btn_RenameActionPerformed(java.awt.event.ActionEvent evt) {                                           

     String VOBpath = txt_VOBpath.getText();
     String CReplica = txt_Currentrepname.getText();
     String NReplica = txt_Newrepname.getText();
     String command = ("cmd /c multitool rename replica:" + CReplica + " "+ NReplica);
     
     File filepath = new File(VOBpath);
     Process p = null;
        try {
           p = Runtime.getRuntime().exec(command, null, filepath);
           int exitVal = p.waitFor();
           //System.out.println("Process exitValue: " + exitVal);
           if(exitVal == 1){
               throw ( new Throwable()); 
           }
        } catch (IOException ex) {
            JOptionPane.showMessageDialog(null,
              "Cannot Rename Replica: " + ex.getMessage(), "Error", JOptionPane.WARNING_MESSAGE);
            return;
        } catch (InterruptedException in){
            JOptionPane.showMessageDialog(null,
              "Cannot Rename Replica: " + in.getMessage(), "Error", JOptionPane.WARNING_MESSAGE);
            return;
        } catch (Throwable T){
             BufferedReader stdInput = new BufferedReader(new 
                 InputStreamReader(p.getInputStream()));
             
             BufferedReader stdOutput = new BufferedReader(new 
                 OutputStreamReader(p.getOutputStream()));
 
            BufferedReader stdError = new BufferedReader(new 
                 InputStreamReader(p.getErrorStream()));

           System.out.println("Process exitValue: " + stdInput);
           System.out.println("Process exitValue: " + stdError);
           
            //JOptionPane.showMessageDialog(null,
              //"Cannot Rename Replica: " + T.getMessage(), "Error", JOptionPane.WARNING_MESSAGE);
            return;
        }
    }