Issue using Runtime.exec() to export a DB

Question

hi ,
i'm trying to write a piece of code to export an oracle DB using Runtime.exec(). I searched the forums and came up a with a piece of code , modified it a bit .The issue is the system sometimes hangs while executing the code , it's like the proc.waitFor() never returns. However the execution is error-free if using a command like 'shutdown' instead of 'exp' .
this is my main
public class DBExporter
           * @param args
          public static void main(String[] args)
                    try
                              StreamReaderThread outReaderThread = new StreamReaderThread();
                              StreamReaderThread errReaderThread = new StreamReaderThread();
                              //StreamReaderThread ww = new StreamReaderThread();
                              Runtime rt = Runtime.getRuntime();
                              outReaderThread.start();
                              errReaderThread.start();
                              String command = "exp beta/beta@frsp_dbS file=\"c:/shop.dmp\" full=\"N\" ";
                              //command = "shutdown -s";
                              Process proc = rt.exec(command);
                              outReaderThread.setInputStream(proc.getInputStream());
                              errReaderThread.setInputStream(proc.getErrorStream());
                              //ww.setOutputStream(proc.getOutputStream());
                              System.out.println(proc.waitFor());
                              proc.getInputStream().close();
                              proc.getErrorStream().close();
                              proc.getOutputStream().close();
                    catch (Exception e)
                              e.printStackTrace();
     }and this is the reader class
import java.io.BufferedWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
*@deprecated
public class StreamReaderThread extends Thread
     private BufferedReader     br;
     private BufferedWriter     bw;
     private StringBuffer     sb;
     private String               newline;
     private String               line;
     public StreamReaderThread()
          br = null;
          sb = null;
          newline = null;
          line = null;
     public synchronized String getText()
          if( sb == null )
               return "";
          return sb.toString();
     private boolean     flag     = false;
     public synchronized void setInputStream( InputStream is )
          br = new BufferedReader(new InputStreamReader(is));
          flag = true;
     public synchronized void setOutputStream( OutputStream is )
               bw = new BufferedWriter(new OutputStreamWriter(is));
               flag = true;
     public synchronized void run()
          int i = 0;
          try
               while( !flag )
                    wait();
               flag = false;
               while( (line = br.readLine()) != null )
                    try
                         if( sb == null )
                              sb = new StringBuffer();
                              newline = System.getProperty("line.separator");
                         else
                              sb.append(newline);
                         sb.append(line);
                    catch( Exception e )
                         e.printStackTrace();
                    i++;
                    if( br == null )
                         break;
          catch( IOException ex )
               ex.printStackTrace();
          catch( InterruptedException ex )
               ex.printStackTrace();
}

Answer 1

Looks like a bug in StreamReaderThread. I can't see that it ever exits the wait() call since no one is calling notify or notify all.
Kaj