Execute a java program from an another program

Question

Like we can compile a code from wihin a java file by using the following :
Tool javac = ToolProvider.getSystemJavaCompiler();
Similarly,can we execute i.e. run a java program from within a java file i.e. running d java command from within the java file ??If yes then please tell me how??

Answer 1

suppose on the Unix box or from a Unix script ( korn, perl, bourne, bash) you can run the following java program
java ${JAVA_OPTS} -jar ${GMR_APPS_DIR}/risk.jar -I -c ${COB} -r ${BATCH} -o ${XML_DIR}
in java you can do the following :
Runtime rt = Runtime.getRuntime();
          try {
               Process process = rt.exec("java ${JAVA_OPTS} -jar ${GMR_APPS_DIR}/risk.jar -I -c ${COB} -r ${BATCH} -o ${XML_DIR}
// OR
               Process process = rt.exec("/export/apps/Tools/apache-tomcat-5.5.17/bin/startup.sh");
               // process.destroy(); if you want to kill the process
               process.waitFor();
               int RC = process.exitValue();      
               System.out.println(returnOutput(process.getErrorStream()));
               System.out.println(returnOutput(process.getInputStream()));
          } catch (Exception ex) {
               ex.printStackTrace();
empty the output stream from the script
private String returnOutput(InputStream is) throws Exception {
               String s;
               StringBuffer strBuff = new StringBuffer();
               BufferedReader br = new BufferedReader(new InputStreamReader(is));
               while ((s = br.readLine()) != null) {
                    strBuff.append(s);
               return strBuff.toString();
          }You need to relace the ${} by the appropriate values.
Regards,
Alan Mehio
London, UK
Edited by: alan_mehio on Jan 16, 2008 4:21 PM