Process output only becomes available after the process has finished

Question

I have a Runnable that reads Console output from an externally called exe (see below) and writes it to both a log file and a JTextArea.

But my Runnable doesn\'t show

Answer 1

You could try the same logic with a SwingWorker instead. You can extend this class, instead of implementing runnable. It could take your Text area as a paramater, and you can publish the data, without having to deal with the SwingUtils.invokeLater, which is guiltily easier...

Try:

public class execute extends javax.swing.SwingWorker {  
      String line;
      Process p; 
      JTextArea jta;

      File f = new File( properties.prop.getProperty( "LOG_FILE_DIR" ) + "\\PartGen.log");

      public execute ( Process process , JTextArea jta ) {
          p = process;
          this.jta = jta;
      }

      //implements a method in the swingworker
      public void doInBackground() throws Exception {
        //Read Process Stream Output and write to LOG file
        BufferedReader is = new BufferedReader( new InputStreamReader(p.getInputStream()));

        while ( (line = is.readLine()) != null ) {
            osfile.writeline(line, f);
            publish(new String(line + "\n"));
        }   
        System.out.flush();  
        return null; 
  }
  //This will happen on the UI Thread.
  public void process(List lines){
      for(Object o : lines){
         jta.append((String)o);
      }
  }

  public void done(){
     try{
        get();
        //You will get here if everything was OK.  So show a popup or something to signal done.
     }catch(Exception ex){
         //this is where your IO Exception will surface, should you have one.
     }
  }
}

Also, in your calling code, which I assume is in your ui somewhere:

    Process p = new ProcessBuilder(command).start();
    execute ex = new execute( p , yourTextArea);
    ex.execute();

I didnt attempt to compile this, so you may have to check against the API, but hopefully it will give you a gist of what to do.