Programming to call other programs

Question

I am in need of direction as I am unable to find any help on my current problem. I am developing a program that will create a database of triples from an xml document. My use of existing programs such as 4suite's '4rdf' which is called by the command prompt has left me with the issue of how do you program in java, to call other programs and/or the command line. I need to pass in arguments and execute the program from within one java program. Is this possible? Help is urgently required. Please help. Cheers Dave.

Answer 1

Allways happy to assist my follow programmers, this is a class I developed (with help from online documents of course) to contain all my executing needs. Note that you need to place these two classes in a package yourself, they are part of quite a complex one where I use them.
public class Semaphore {
  protected boolean blocked;
  public Semaphore() { blocked = false; }
  public synchronized void waitUntilSignalled() {
       if(blocked == false){
         try {
                blocked = true;
                wait();
            } catch(  InterruptedException e ) { }
  public synchronized void setSignalled() {
    if (blocked == true){
          blocked = false;
          notifyAll();
     public static class ExecStreamThread extends Thread
         InputStream is;
         OutputStream os;
         Semaphore sem;
         public ExecStreamThread(InputStream is, OutputStream redirect)
             this.is = is;
             this.os = redirect;
             sem = null;
         public ExecStreamThread(InputStream is, OutputStream redirect, Semaphore theSem)
             this.is = is;
             this.os = redirect;
             sem = theSem;
         public void run()
              try
                   PrintWriter pw = pw = new PrintWriter(os);
                   InputStreamReader isr = new InputStreamReader(is);
                   BufferedReader br = new BufferedReader(isr);
                   String line=null;
                   while ( (line = br.readLine()) != null)
                            pw.println(line);
                       pw.flush();
              } catch (IOException ioe){
                  // don't have to do anything, the parent thread will have found out the process errored
              // run is complete, signal the semaphore
              if(sem != null){
                   sem.setSignalled();
     public static final int OSTYPE_WINDOWS = 1;
     public static final int OSTYPE_WINNT = 2;
     public static final int OSTYPE_WINCE = 3;
     public static final int OSTYPE_LINUX = 4;
     public static final int OSTYPE_MAC = 5;
     public static final int OSTYPE_SOLARIS = 6;
     public static final int OSTYPE_NETWARE = 7;
     public static final int OSTYPE_OS2 = 8;
     public static final int OSTYPE_UNKNOWN = 9;
     private static int type = OSTYPE_UNKNOWN;
     private ExecUtil()
          @return an integer identifying the OS (one of the OSTYPE constants)
     public static int getOs()
          if(type == OSTYPE_UNKNOWN){
               String osname = System.getProperty("os.name").toLowerCase();
               if(osname.indexOf("windows") != -1){
                    if(osname.indexOf("nt") != -1 || osname.indexOf("2000") != -1 || osname.indexOf("xp") != -1){
                         type = OSTYPE_WINNT;
                    } else if(osname.indexOf("ce") != -1){
                         type = OSTYPE_WINCE;
                    } else {
                         type = OSTYPE_WINDOWS;
               } else if(osname.indexOf("linux") != -1 || osname.indexOf("bsd") != -1){
                    type = OSTYPE_LINUX;     
               } else if(osname.indexOf("mac os") != -1 || osname.indexOf("macos") != -1){
                    type = OSTYPE_MAC;
               } else if(osname.indexOf("solaris") != -1){
                    type = OSTYPE_SOLARIS;     // could also be old freebsd version
               } else if(osname.indexOf("netware") != -1){
                    type = OSTYPE_NETWARE;
               } else if(osname.indexOf("os/2") != -1){
                    type = OSTYPE_OS2;
               } else {
                    type = OSTYPE_UNKNOWN;     
          return type;
          @return the prefix to execute a shell command. For example "command /c " to execute a shell command on windows9X machines.
     public static String getShellString()
             String appendStr = "";
             int ostype = getOs();
             if(ostype == OSTYPE_WINDOWS){
                  appendStr = "command /c ";
             } else if(ostype == OSTYPE_WINNT || ostype == OSTYPE_WINCE){
                  appendStr = "cmd /c ";     
             } else if(ostype == OSTYPE_LINUX || ostype == OSTYPE_MAC){
                  appendStr = "/bin/sh -c ";     
             } // add other shell executers
             return appendStr;
     /** execute a command and ignore any output it generates (output is sent to System.out and System.err).
          It is valid to pass a command containing multiple parameters
          @param command the command to execute
          @return the exit code the process generated
     public static int exec(String command)
          throws IOException
          return exec(command, false, System.out, System.err);
     /** execute a (shell) command and ignore any output it generates (output is sent to System.out and System.err).
          It is valid to pass a command containing multiple parameters.
          NOTE: only windows (command), winnt (cmd) and linux (sh) shell executions are supported.
          @param command the command to execute
          @param shellCommand should the command be handled as an internal shell command?
          @return the exit code the process generated
     public static int exec(String command, boolean shellCommand)
          throws IOException
          return exec(command, shellCommand, System.out, System.err);
     /** execute a (shell) command and catch the output it generates.
          It is valid to pass a command containing multiple parameters.
          NOTE: only windows (command), winnt (cmd) and linux (sh) shell executions are supported.
          @param command the command to execute
          @param shellCommand should the command be handled as an internal shell command?
          @param output the output stream to send the output of the process to (output is handled as textual data)
          @return the exit code the process generated
     public static int exec(String command, boolean shellCommand, OutputStream output)
          throws IOException
          return exec(command, shellCommand, output, System.err);
     /** execute a command and catch the output it generates.
          It is valid to pass a command containing multiple parameters.
          @param command the command to execute
          @param output the output stream to send the output of the process to (output is handled as textual data)
          @return the exit code the process generated
     public static int exec(String command, OutputStream output)
          throws IOException
          return exec(command, false, output, System.err);
     /** execute a command and catch the output (stdout) and errors (stderr) it generates.
          It is valid to pass a command containing multiple parameters.
          @param command the command to execute
          @param output the output stream to send the output of the process to (output is handled as textual data)
          @param error the output stream to send the error output of the process to (output is handled as textual data)
          @return the exit code the process generated
     public static int exec(String command, OutputStream output, OutputStream error)
          throws IOException
          return exec(command, false, output, error);
     /** execute a command and catch the output (stdout) and errors (stderr) it generates.
          It is valid to pass a command containing multiple parameters.
          NOTE: only windows (command), winnt (cmd) and linux (sh) shell executions are supported.
          @param command the command to execute
          @param shellCommand should the command be handled as an internal shell command?
          @param output the output stream to send the output of the process to (output is handled as textual data)
          @param error the output stream to send the error output of the process to (output is handled as textual data)
          @return the exit code the process generated
     public static int exec(String command, boolean shellCommand, OutputStream output, OutputStream error)
          throws IOException
         if(shellCommand == true){
              String appendStr = getShellString();
              command = appendStr + command;
         String[] realcommand;
         if(command.indexOf(" ") != -1){
              realcommand = command.split(" ");
         } else {
              realcommand = new String[1];
              realcommand[0] = command;     
         try{
              Process ls_proc = Runtime.getRuntime().exec(realcommand);
               ExecStreamThread execOutput;
               ExecStreamThread execError;
               execOutput = new ExecStreamThread(ls_proc.getInputStream(), output);
               execOutput.start();
               execError = new ExecStreamThread(ls_proc.getErrorStream(), error);
               execError.start();
             int exitvalue = ls_proc.waitFor();     
               if(output != null) { output.flush(); }
               if(error != null) { error.flush(); }
               return exitvalue;
          } catch(Exception e){
               throw new IOException(e.getMessage());
     public static void main(String[] args)
          try{
               int code = ExecUtil.exec("javac test.java", System.out, System.err);
               System.out.println("Exit code was : " + code);
               code = ExecUtil.exec("java test", System.out, System.err);
               System.out.println("Exit code was : " + code);
          } catch(IOException e){
               System.out.println("failed due to exception: " + e);
          try{
               int code = ExecUtil.exec("dir/w", true, System.out, System.err);
               System.out.println("Exit code was : " + code);
          } catch(IOException e){
               System.out.println("failed due to exception: " + e);
}