Develop Reference

Java - how to call Java main() from a new process thread

I am trying to build out Integration Tests (IT) for an application. The application has at its centre a Server, written in Java, that set-ups a message queue from which it polls for messages sent to it on a particular port-number. I would like to write an Integration Test which fires some messages at this server/port-number and tests the response.
Below is the full list of VM arguments that I run when I start the server from within Intellij manually. I can start the server this way and then fire my test messages at it but I would like to convert this into IT tests so that I can start/stop the server programmatically at the start and end of my tests.
The problem I am having is that I dont know how to start the server application from within my test class. So to ask it more plainly, how to start the Java main() of a class in its own process thread. I am working within Intellij (2019.1) and Java 8. Should I be using the ProcessBuilder or ExecutorService maybe ?
I think I can use System.setProperty for some of the VM arguments but not sure how to specify the -XX ones...so that would be a second part to this question.
-Djava.endorsed.dirs=/Users/xxx/dev/src/repo/xxx/myapp/target/classes/lib/endorsed
-Dmyapp.home=/private/var/tmp/myapp
-Dmyapp.log.dir=/private/var/tmp
-Dmyapp.env=/Users/xxx/dev/src/repo/xxx/myapp/target/classes/etc/examples/environment-apa.sh
-Dsimplelogger.properties=/private/var/tmp/myapp/etc/simplelogger.properties
-server
-XX:CompileThreshold=2500
-XX:+UseFastAccessorMethods
-Xss256k
-Xmx1g
-Xms512m
I've tried implementing this using the ExecutorService
public class ServerTest {
#Test
public void shouldStartServerOk() {
try{
startServer();
}catch(Exception e){
e.printStackTrace();
fail();
}
}
private void startServer(){
ExecutorService executor = Executors.newFixedThreadPool(1);
Runnable runnableTask = new Runnable() {
#Override
public void run() {
String [] args = new String[0];
try {
System.setProperty("java.endorsed.dirs", "/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/lib/endorsed");
System.setProperty("myapp.home", "/private/var/tmp/myapp");
System.setProperty("myapp.log.dir", "/private/var/tmp");
System.setProperty("myapp.env", "/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/etc/examples/environment-apa.sh");
System.setProperty("simplelogger.properties", "/private/var/tmp/myapp/etc/simplelogger.properties");
System.setProperty("-server", "TRUE");
MyApp.main(args);
} catch (Exception e) {
e.printStackTrace();
}
}
};
executor.execute(runnableTask);
// shut down the executor manually
//executor.shutdown();
}
But this doesn't seem to work although the test does complete green. When I debug the process, the flow doesn't Step-Into MyApp.main(args). Strangely when I just try running MyApp.main(args) on its own outside of the ExecutorService then it starts and runs fine until I hit Stop in my IDE. This is behaviour I would like just the additional ability to Start/Stop the process.
UPDATE-1:
following the comments from #dmitrievanthony and #RealSkeptic I have tried to implement something along those lines based on SO question, Executing a Java application in a separate process/636367,
public final class JavaProcess {
private JavaProcess() {}
public static int exec(Class klass) throws IOException,
InterruptedException {
String javaHome = System.getProperty("java.home");
String javaBin = javaHome +
File.separator + "bin" +
File.separator + "java";
String classpath = System.getProperty("java.class.path");
String className = klass.getName();
ProcessBuilder processBuilder = new ProcessBuilder(
javaBin,
"-cp",
classpath,
className
);
Map<String, String> env = processBuilder.environment();
env.put("java.endorsed.dirs", "/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/lib/endorsed");
env.put("myapp.home", "/private/var/tmp/myapp");
env.put("myapp.log.dir", "/private/var/tmp");
env.put("myapp.env", "/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/etc/examples/environment-apa.sh");
env.put("simplelogger.properties", "/private/var/tmp/myapp/etc/simplelogger.properties");
env.put("-XX:CompileThreshold", "2500");
env.put("-XX:+UseFastAccessorMethods", "");
env.put("-Xss256k", "");
env.put("-Xmx1g", "");
env.put("-Xms512m", "");
Process process = processBuilder.inheritIO().start();
process.waitFor();
return process.exitValue();
}
and calling it in my myAppIT test class as int status = JavaProcess.exec(MyAapp.class);
I can now see my class "MyApp" starting - and can confirm that the process flow is running into my MyApp.main() class. The problem now is that the System.env variables that I am setting in my ProcessBuilder do not appear to be available in the called programme ie. when I print to log System.getProperty("myapp.home") its returning null even though I can confirm that it is being set as shown in the code - does anyone have any ideas on this one please ?
UPDATE-2: I am trying to implement suggestion by #RealSkeptic and passing in the arguments in a similar way as passing commandline arguments as shown in the code snippet below. Now I am getting an exception
Error: Could not find or load main class xxx.xxx.xxx.xxx.MyApp -Djava.endorsed.dirs=.Users.xxx.dev.src.gitlab.myapp.myapp.target.classes.lib.endorsed
one problem I see is that the forward slashes of the path have been translated to ".". The path should read, Djava.endorsed.dirs=/Users/xxx/dev/src/gitlab/myapp/myapp/target/classes/lib/endorsed
ProcessBuilder processBuilder = new ProcessBuilder(
javaBin,
"-cp",
classpath,
className + " " +
"-Djava.endorsed.dirs=" + "/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/lib/endorsed " +
"-Dmyapp.home=/private/var/tmp/myapp " +
"-Dmyapp.log.dir=/private/var/tmp" +
"-Dmyapp.env=/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/etc/examples/environment-apa.sh " +
"-Dsimplelogger.properties=/private/var/tmp/myapp/etc/simplelogger.properties " +
"-server " +
"-XX:CompileThreshold=2500 " +
"-XX:+UseFastAccessorMethods " +
"-Xss256k " +
"-Xmx1g " +
"-Xms512m"
);
Update-3 following the last comment from #RealSkeptic I've modified my code (see below) and this now works.
ProcessBuilder processBuilder = new ProcessBuilder(
javaBin,
"-cp",
classpath,
"-Djava.endorsed.dirs=" + "/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/lib/endorsed",
"-Dmyapp.home=/private/var/tmp/myapp",
"-Dmyapp.log.dir=/private/var/tmp",
"-Dmyapp.env=/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/etc/examples/environment-apa.sh",
"-Dsimplelogger.properties=/private/var/tmp/myapp/etc/simplelogger.properties ",
"-server",
"-XX:CompileThreshold=2500",
"-XX:+UseFastAccessorMethods",
"-Xss256k",
"-Xmx1g",
"-Xms512m",
className
);

The below is copied from UPDATE-3 which I am posting as the answer. Thank you to those who responded and especially #RealSkeptic.
ProcessBuilder processBuilder = new ProcessBuilder(
javaBin,
"-cp",
classpath,
"-Djava.endorsed.dirs=" + "/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/lib/endorsed",
"-Drrc.home=/private/var/tmp/myapp",
"-Drrc.log.dir=/private/var/tmp",
"-Drrc.env=/Users/xxx/dev/src/gitlab/xxx/myapp/target/classes/etc/examples/environment-apa.sh",
"-Dsimplelogger.properties=/private/var/tmp/myapp/etc/simplelogger.properties ",
"-server",
"-XX:CompileThreshold=2500",
"-XX:+UseFastAccessorMethods",
"-Xss256k",
"-Xmx1g",
"-Xms512m",
className
);
I have refactored the above to put each of the arguments into a List so the call to ProcessBuilder reduces to,
ProcessBuilder processBuilder = new ProcessBuilder(arguments);
Process process = processBuilder.inheritIO().start();
To Stop the process you just need to call
process.destroy();

Unable to run Java code on MATLAB Runtime in Unix environment

After exporting a matlab function to java package. I have tried to run the following code unix environment which contains MATLAB runtime.
import com.mathworks.toolbox.javabuilder.MWArray;
import com.mathworks.toolbox.javabuilder.MWCharArray;
import calibrationAPINew.Calibration;
public class CHIndexCalculation {
public static void main(String[] args) {
MWCharArray number1 = null;
Object[] result = null;
Calibration calibration = null;
String data = "{\r\n" +
"\"tsId\" : \"121213\",\r\n" +
"\"datapoints\" : [0.1,0.2,0.3,0.4]\r\n" +
"}";
try
{
System.out.println("Input data: " + data);
number1 = new MWCharArray(data); // Array of Input to be sent to MATLAB Runtime
System.out.println("MWCharArray: " + number1);
calibration = new Calibration();
result = calibration.calibrationAPI(1,number1);
System.out.println("Output : " + result[0]);
}
catch (Exception e)
{
System.out.println("Exception Occurred : " + e);
e.printStackTrace();
}
finally
{
//MWArray.disposeArray(number1);
//MWArray.disposeArray(result);
//calibration.dispose();
}
}
}
I have installed the matlabruntime on unix box and set the environment variables using export statement
export LD_LIBRARY_PATH=matlabrt/v92/runtime/glnxa64:matlabrt/v92/bin/glnxa64:matlabrt/v92/sys/os/glnxa64:matlabrt/v92/sys/opengl/lib/glnxa64
Now when I try to run the command ( calibrationAPINew.jar is the jar file exported from MATLAB)
java -cp javabuilder.jar:calibrationAPINew.jar:. CHIndexCalculation
I get the following exception
com.mathworks.toolbox.javabuilder.MWException: Undefined function 'pdist2mex' for input arguments of type 'double'.
at com.mathworks.toolbox.javabuilder.internal.MWMCR.mclFeval(Native Method)
at com.mathworks.toolbox.javabuilder.internal.MWMCR.access$600(MWMCR.java:31)
at com.mathworks.toolbox.javabuilder.internal.MWMCR$6.mclFeval(MWMCR.java:882)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.mathworks.toolbox.javabuilder.internal.MWMCR$5.invoke(MWMCR.java:769)
at com.sun.proxy.$Proxy0.mclFeval(Unknown Source)
at com.mathworks.toolbox.javabuilder.internal.MWMCR.invoke(MWMCR.java:443)
at calibrationAPINew.Calibration.calibrationAPI(Calibration.java:223)
at CHIndexCalculation.main(CHIndexCalculation.java:24)
I know this has something to do with MATLAB runtime but I am unable to figure out what ? The same set up works fine on windows environment.

I think the matlab program uses some mexfile which is already compiled for windows, so that it is working perfect on windows. Since the mexfile is already available it will work perfect on windows. But when your script failed to find the corresponding mexfile for linux it fails or tries to compile the source files for linux using the function 'pdist2mex' which is not included in the jar package.In windows there is no need of this function so it works fine. If this is the case then you can either add the function 'pdist2mex' to your jar from matlab or you should compile the sources to linux compatible mex-file manually using matlab and then try to repackage it then the matlab automatically wrap the corresponding mex file to the jar

Basic Java Runtime program cannot find python

Hello working on a small program that just needs to run a python script I have. This python script will play a given .wav file, and draw a shape on the turtle screen. As such, I'm not looking for an output to be returned to java. Here is my java code:
public class Driver {
public static void main(String[] args){
try {
Process p = Runtime.getRuntime().exec("python " +
" D:/Coding Files/Python/MusicColors.py" +" teenagers.wav");
}
catch (Exception e){
System.out.println(e);
}
}
}
The exception I get is:
java.io.IOException: Cannot run program "python":
CreateProcess error=2, The system cannot find the file specified
I probably am making a very stupid mistake as I have limited knowledge in the subject of processes and such. I added python to my system path, so whenever I put "python" into command line, it returns with
Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 25 2016, 22:01:18) [MSC v.1900 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
And makes it the python shell.
Here is the exact line I added to my environment path:
C:\Users\Joe\AppData\Local\Programs\Python\Python35-32
If anyone can figure out where I went wrong I'd really appreciate it!

The $PATH variable you've set is not inherited in Java's execution context. Try passing the Python's bin path to exec()'s execution environment.
To do this, the code below first retrieve all the environment variables and create an array of ENV_KEY=ENV_VALUE pairs.
Then, the path to your Python's bin is appended to the PATH value.
Finally, we pass the array of all environment variables to exec() (via the second parameter).
import java.util.HashMap;
import java.util.Map;
public class Driver {
public static void main(String[] args){
try {
String[] commands = {"python D:/Coding Files/Python/MusicColors.py teenagers.wav"};
// Get a list of all environment variables
final Map<String, String> envMap = new HashMap<String, String>(System.getenv());
// Append Python bin path to Path
envMap.put("Path", envMap.get("Path") + ";C:/Users/Joe/AppData/Local/Programs/Python/Python35-32");
// Convert to an array of ENV_KEY=ENV_VALUE format strings
final String[] envs = new String[envMap.size()];
int i = 0;
for (Map.Entry<String, String> e : envMap.entrySet()) {
envs[i] = e.getKey() + '=' + e.getValue();
i++;
}
// Exec with the environment variables
Process p = Runtime.getRuntime().exec(commands, envs);
}
catch (Exception e){
System.out.println(e);
}
}
}

Elevate Java application while running

A nasty problem popped out with my software. I am making a program that interacts with another existing software (a game). User has reported that he runs the game with administrator privileges and under that circumstances, my program stops working for him.
Short investigation revealed that some people really need to run the game under administrator account and some don't. It would be great if my program would be able to detect this and warn user if the game is running under administrator account:
If the user clicks "Elevate", I'd like to ask windows to elevate the java.exe running my jar file and invoke the typical UAC dialog.
Obviously, this time the question would not be about java updater but JRE
My question is: Is this possible? Can windows elevate my java.exe instance's privilege? Does java have a way to do it? Or can I use command line command?
I want to avoid restarting the program (though it wouldn't probably be such a big deal).
Edit:
If you look in the comments, you'll see that there's no avoiding the restart of an application - process can only start elevated, not become elevated. This kinda shifts the question, unfortunately. Basically, it now sounds more like: "How to restart my application with admin rights?". Unless, of course, there's a trick like two java.exe sharing one jar...

If still of interest: In Windows 7 my JavaElevator works. It elevates a running Java process when used in the main method of the Java application. Simply add -elevate as last program parameter and use the elevator in the main method.
The elevator class:
package test;
import com.sun.jna.Native;
import com.sun.jna.platform.win32.Kernel32;
import com.sun.jna.platform.win32.Kernel32Util;
import com.sun.jna.platform.win32.ShellAPI;
import com.sun.jna.platform.win32.WinDef;
/**
* Elevates a Java process to administrator rights if requested.
*/
public class JavaElevator {
/** The program argument indicating the need of being elevated */
private static final String ELEVATE_ARG = "-elevate";
/**
* If requested, elevates the Java process started with the given arguments to administrator level.
*
* #param args The Java program arguments
* #return The cleaned program arguments
*/
public static String[] elevate(String[] args) {
String[] result = args;
// Check for elevation marker.
boolean elevate = false;
if (args.length > 0) {
elevate = args[args.length - 1].equals(ELEVATE_ARG);
}
if (elevate) {
// Get the command and remove the elevation marker.
String command = System.getProperty("sun.java.command");
command = command.replace(ELEVATE_ARG, "");
// Get class path and default java home.
String classPath = System.getProperty("java.class.path");
String javaHome = System.getProperty("java.home");
String vm = javaHome + "\\bin\\java.exe";
// Check for alternate VM for elevation. Full path to the VM may be passed with: -Delevation.vm=...
if (System.getProperties().contains("elevation.vm")) {
vm = System.getProperty("elevation.vm");
}
String parameters = "-cp " + classPath;
parameters += " " + command;
Shell32.INSTANCE.ShellExecute(null, "runas", vm, parameters, null, 0);
int lastError = Kernel32.INSTANCE.GetLastError();
if (lastError != 0) {
String errorMessage = Kernel32Util.formatMessageFromLastErrorCode(lastError);
errorMessage += "\n vm: " + vm;
errorMessage += "\n parameters: " + parameters;
throw new IllegalStateException("Error performing elevation: " + lastError + ": " + errorMessage);
}
System.exit(0);
}
return result;
}
}
Usage in the main method of the Java application:
public static void main(String[] args) {
String[] args1 = JavaElevator.elevate(args);
if (args1.length > 0) {
// Continue as intended.
...
I know, this is a very basic implementation - sufficient for one of my daily hiccups: Starting an elevated process from Eclipse. But maybe it points someone in some dicrection...

As has been pointed in comments, sadly the Java (or any other process) cannot be elevated while running. While in the case of JWM, it could be theoretically possible to move whole program context from normal user java.exe to elevated one, I don't think it's possible. I hope some day someone will come and tell me I'm wrong.
Surprisingly, even with restart in place, this was a tricky task that took me a while to figure out.
The non java part
First, how do we exactly run a program elevated from command line? There's an answer and you can see it's not simple. But we can break it to this VBS script:
Set UAC = CreateObject("Shell.Application")
UAC.ShellExecute "program name", "command line parameters", "working directory", "runas", 1
Soon, it also turns out that we won't have any success running java.exe from VBS script. In the end, I decided to run a helper batch file. Finally, here (answer to question in the last link) we have a complete set of two scripts which really run the given .jar file elevated. Here's improved version that allows quick testing by drag'n'dropping the Jar file on it:
' Require first command line parameter
if WScript.Arguments.Count = 0 then
MsgBox("Jar file name required.")
WScript.Quit 1
end if
' Get the script location, the directorry where it's running
Set objShell = CreateObject("Wscript.Shell")
strPath = Wscript.ScriptFullName
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objFile = objFSO.GetFile(strPath)
strFolder = objFSO.GetParentFolderName(objFile)
'MsgBox(strFolder)
' Create the object that serves as runnable something
Set UAC = CreateObject("Shell.Application")
' Args:
' path to executable to run
' command line parameters - first parameter of this file, which is the jar file name
' working directory (this doesn't work but I use it nevertheless)
' runas command which invokes elevation
' 0 means do not show the window. Normally, you show the window, but not this console window
' which just blinks and disappears anyway
UAC.ShellExecute "run-normally.bat", WScript.Arguments(0), strFolder, "runas", 0
WScript.Quit 0
The Java part
Java part is more straightforward. What we need to do is to open new process and execute the prepared scripts in it.
/**
* Start this very jar file elevated on Windows. It is strongly recommended to close any existing IO
* before calling this method and avoid writing anything more to files. The new instance of this same
* program will be started and simultaneous write/write or read/write would cause errors.
* #throws FileNotFoundException if the helper vbs script was not found
* #throws IOException if there was another failure inboking VBS script
*/
public void StartWithAdminRights() throws FileNotFoundException, IOException {
//The path to the helper script. This scripts takes 1 argument which is a Jar file full path
File runAsAdmin = new File("run-as-admin.vbs");;
//Our
String jarPath;
//System.out.println("Current relative path is: " + s);
try {
jarPath = "\""+new File(Main.class.getProtectionDomain().getCodeSource().getLocation().toURI().getPath()).getAbsolutePath()+"\"";
} catch (URISyntaxException ex) {
throw new FileNotFoundException("Could not fetch the path to the current jar file. Got this URISyntax exception:"+ex);
}
//If the jar path was created but doesn't contain .jar, we're (most likely) not running from jar
//typically this happens when running the program from IDE
//These 4 lines just serve as a fallback in testing, should be deleted in production
//code and replaced with another FileNotFoundException
if(!jarPath.contains(".jar")) {
Path currentRelativePath = Paths.get("");
jarPath = "\""+currentRelativePath.toAbsolutePath().toString()+"\\AutoClient.jar\"";
}
//Now we check if the path to vbs script exists, if it does we execute it
if(runAsAdmin.exists()) {
String command = "cscript \""+runAsAdmin.getAbsolutePath()+"\" "+jarPath;
System.out.println("Executing '"+command+"'");
//Note that .exec is asynchronous
//After it starts, you must terminate your program ASAP, or you'll have 2 instances running
Runtime.getRuntime().exec(command);
}
else
throw new FileNotFoundException("The VBSScript used for elevation not found at "+runAsAdmin.getAbsolutePath());
}

This is my version. It creates a VBScript script, then executes it. This only works if the program that is being run is in a jar file, so you will have to run your IDE as administrator to actually test your program.
public static void relaunchAsAdmin() throws IOException {
relaunchAsAdmin(ThisClass.class); //Change ThisClass to the class that this method is in
}
public static void relaunchAsAdmin(Class<?> clazz) throws IOException {
if(isCurrentProcessElevated()) {
return;
}
final String dir = System.getProperty("java.io.tmpdir");
final File script = new File(dir, "relaunchAsAdmin" + System.nanoTime() +
".vbs");
try {
script.createNewFile();
OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream(script));
osw.append("Set s=CreateObject(\"Shell.Application\")" + ln + "s.ShellExecute \"" +
System.getProperty("java.home") + "\\bin\\java.exe" + "\",\"-jar \"\"" +
new File(clazz.getProtectionDomain().getCodeSource(
).getLocation().toURI()).getAbsolutePath() + "\"\"\",,\"runas\",0" +
ln + "x=createObject(\"scripting.fileSystemObject\").deleteFile(" +
"WScript.scriptfullname)");
osw.close();
if(System.getenv("processor_architecture").equals("x86")) {
Runtime.getRuntime().exec("C:\\Windows\\System32\\wscript.exe \"" +
script.getAbsolutePath() + "\"");
} else {
Runtime.getRuntime().exec("C:\\Windows\\SysWoW64\\wscript.exe \"" +
script.getAbsolutePath() + "\"");
}
} catch(URISyntaxException e) {
e.printStackTrace();
}
Runtime.getRuntime().exit(0);
}
Note that it is a bit messy. I have been using this method before, so it has been line wrapped to 100 characters (except the comment I wrote for this answer). The
isCurrentProcessElevated()
method will have to be implemented in one way or another. You could try using JNI, or you could use a pure Java method, such as writing in the Program Files or System32 directory and seeing if it failed.
Obviously, this solution will only work on Windows. I never needed to elevate on Linux or Mac systems (mainly because I don't have any Mac systems, and I don't use Linux - I just play with it).

set windows PATH environment variable at runtime in Java

I have a java program that fires off an executable using the Runtime.exec() method. I'm using the variant that takes in a set of command line params as one argument, and some environment variables as another argument.
The environment variable I'm tryign to set is path, so i'm passing in "PATH=C:\some\path". This does not work. Is there some trick to this or any alternatives. I am stuck to Java 1.4 unfortunately.

Use getenv to get the environment and fix it up then use a flavour of exec to do the exec.
This works with a batch file that has path in it.
package p;
import java.util.*;
public class Run {
static String[] mapToStringArray(Map<String, String> map) {
final String[] strings = new String[map.size()];
int i = 0;
for (Map.Entry<String, String> e : map.entrySet()) {
strings[i] = e.getKey() + '=' + e.getValue();
i++;
}
return strings;
}
public static void main(String[] arguments) throws Exception {
final Map<String, String> env = new HashMap<String, String>(System.getenv());
env.put("Path", env.get("Path") + ";foo");
final String[] strings=mapToStringArray(env);
Runtime.getRuntime().exec("cmd /C start foo.bat",strings);
}
}

If "PATH=C:\some\path" appears in your source code, it would be incorrect as it would be trying to escape the 's' and 'p' in that string, you'd use "PATH=C:\\some\\path" instead (escaping the slashes). Also, you don't want to pass it in as a string directly, but as an array of strings (likely with that as the only string in it).

If you want to change the Path variable on windows, you should take a look at JNI_Registry: http://www.trustice.com/java/jnireg/
It's a Java binding to the Windows Registry API and comes with a very small footprint.
I have used it for my current project and it works just fine.

One solution might be to add an additional command to "exec" where you set the path ... as in the example found here:
http://www.neowin.net/forum/topic/620450-java-runtimegetruntimeexec-help/
excerpt:
cmd = new String[7];
cmd[0] = "cmd";
cmd[1] = "/C";
cmd[2] = "set PATH=C:\\Program Files\\Java\\jdk1.6.0_04\bin";
cmd[3] = "copy " + "\"" +path + "\\" +name+ "\"" + " C:\\java";
cmd[4] = "chdir C:\\java";
cmd[5] = "javac *.java";
cmd[6] = "jar cmf mainClass.txt"+" name"+".jar *.class";
try{
Runtime.getRuntime().exec(cmd);