Launching another VM instance using Runtime.exec()

Hi,
I have two separate Swing applications, say A and B. I need to launch B from A using Runtime.exec() - essentially I am launching another VM instance from one VM. I am encountering strange problems - B's main window comes up, but GUI doesn't update; sometimes B comes up and GUI updates, but huge memory leaks happen. All the problems with B go away once A is shut down. It almost looks like both the instances of VM are sharing (or competing for) the event thread. Any comments will be of great help. Thanks.
note: There is no problem launching B if A is a console java application (i.e. no Swing GUI).

I have recently had the same problem, especially with the part where it seems like the two applications are sharing or competing for the same event thread. Sometimes my application B hangs like it is stuck waiting for an event. Sometimes I can get it to unhang by moving the app window around or minimizing it. If it does break free, all the queued events occur in rapid succession. Anybody have any clue what's going on here? It's pretty annoying.

Similar Messages

How can i launch another java application using Runtime class?

I created a java process which invokes another java application called Launch as shown below,
Process p=Runtime.getRuntime().exec("java -classpath=C:\\Program Files\\bin\\nettools\\ui\\updates Launch");
But it is not working...can any one help me on this?
Edited by: deepakchandaran on Sep 20, 2007 7:10 AM

You could search the forum and Google.
it has been answered before.
http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html

Launching another Swing application from existing one using Runtime.exec()

Hi,
I have two separate Swing applications, say A and B. I need to launch B from A using Runtime.exec() - essentially I am launching another VM instance from one VM. I am encountering strange problems - B's main window comes up, but GUI doesn't update; sometimes B comes up and GUI updates, but huge memory leaks happen. All the problems with B go away once A is shut down. It almost looks like both the instances of VM are sharing (or competing for) the event thread. Any comments will be of great help. Thanks.
note: There is no problem launching B if A is a console java application (i.e. no Swing GUI).

Do you have to have the second application running in a seperate VM (process)? If not completely neccesary, then you can just invoke the static main() of the second class. If the type of the second class isn't known untill run-time, you can use Reflection to invoke the method.
Miguel

How to copy .gif files from one dir to another using runtime.exec

hello sir/madem,
i want to copy some gif and jepg files from one directory to another dir using swing.
when i tried with using runtime.exec(String[]) i am getting the following error.
anybody please tell me what is the problem in my program
java.io.IOException: CreateProcess: ren c:/windows/desktop/copy.java c:/windows/
cc.java error=0
code:
public class copy
     public static void main(String[] args)
          try{
               String s[]=new String[3];
                    s[0]="ren";
s[1]="c:/windows/desktop/copy.java";
s[2]="c:/windows/cc.java";
          Runtime rt=Runtime.getRuntime();
Process p=rt.exec(s);
          int i=p.waitFor();
          System.out.println("i is "+i);
          }catch(Exception e){System.out.println(e);}
please mail me to [email protected]
thanks in advance
samba reddy
india

why use the Runtime? There are methods for this in the IO package ...

Can we run a java application using Runtime.exec()?

Can we run a java application using Runtime.exec()?
If yes what should i use "java" or "javaw", and which way?
r.exec("java","xyz.class");

The best way to run the java application would be to dynamiically load it within the same JVM. Look thru the class "ClassLoader" and the "Class", "Method" etc...clases.
The problem with exec is that it starts another JVM and moreover you dont have the interface where you can throw the Output directly.(indirectly it can be done by openong InputStreams bala blah............). I found this convenient. I am attaching part of my code for easy refernce.
HIH
ClassLoader cl = null;
Class c = null;
Class cArr[] ;
Method md = null;
Object mArr[];
cl = ClassLoader.getSystemClassLoader();
try{
     c = cl.loadClass(progName.substring(0,progName.indexOf(".class")) );
} catch(ClassNotFoundException e) {
System.out.println(e);
     cArr = new Class[1] ;
     try{
     cArr[0] = Class.forName("java.lang.Object");
     } catch(ClassNotFoundException e) {
     System.out.println(e);
     mArr = new Object[1];
     try{
     md = c.getMethod("processPkt", cArr);
     } catch(NoSuchMethodException e) {
     System.out.println(e);
     } catch(SecurityException e) {
     System.out.println(e);
try {
processedPkt = md.invoke( null, mArr) ;
} catch(IllegalAccessException e) {
          System.out.println(e);
} catch(IllegalArgumentException e) {
          System.out.println(e);
}catch(InvocationTargetException e) {
          System.out.println(e);
}catch(NullPointerException e) {
          System.out.println(e);
}catch(ExceptionInInitializerError e) {
          System.out.println(e);
}

Trying to run external script using Runtime.exec

Hey,
I am trying to use Runtime.exec(cmd, evnp, dir) to execute a fortran program and get back its output, however it seems to always be hanging. Here is my code snippet :
            Process process = Runtime.getRuntime().exec(
                  "./fortranCodeName > inputFile.txt" , null, new File("/home/myRunDir/"));
            InputStream stream = new InputStream(process.getInputStream());
            InputStream error = new InputStreamr(process.getErrorStream());
            BufferedReader stdoutReader = new BufferedReader(new InputStreamReader(stream));
            BufferedReader erroutReader = new BufferedReader(new InputStreamReader(error));
            System.out.println(stream.available()); //returns 0
            System.out.println(error.available());     //returns 0
            while (true) {
                String line1 = stdoutReader.readLine(); //hangs here
                String line2 = erroutReader.readLine();
                if (line1 == null) {
                    break;
                System.out.println(line1);
                System.out.println(line2);
            }I know for a fact that this fortran code prints out stuff when run it in terminal, but I don't know if I have even set up my Runtime.exec statement properly. I think I am clearing out my error and input streams with the whole reader.readLine bit I have above, but I am not sure. If you replace the command with something like "echo helloWorld" or "pwd", it prints out everything properly. I also am fairly confident that I have no environmental variables that are used in the fortran code, as I received it from another computer and haven't set up any in my bash profile.
Any Ideas?

Okay, so I implemented the changes from that website (thanks by the way for that link, it helps me understand this a little better). However, my problem is still occuring. Here is my new code:
            class StreamThread extends Thread {
            InputStream is;
            String type;
            StreamThread(InputStream is, String type)
                this.is = is;
                this.type = type;
            public void run()
                try
                    InputStreamReader isr = new InputStreamReader(is); //never gets called
                    BufferedReader br = new BufferedReader(isr);
                    String line=null;
                    while ( (line = br.readLine()) != null)
                        System.out.println(type +">"+ line);
                    } catch (IOException ioe)
                        ioe.printStackTrace();
        try {
            Process process = Runtime.getRuntime().exec(
                  "./fortranCodeName" , null, new File("/home/myRunDir/"));
            StreamThread stream = new StreamThread(process.getInputStream(), "OUTPUT");
            StreamThread errorStream = new StreamThread(process.getInputStream(), "ERROR");
            stream.start();
            errorStream.start();
            int exitVal = process.waitFor(); //hangs here
            System.out.println("ExitValue: " + exitVal);

IOException File not found - While using Runtime.exec

Hey All,
I have written a Java application which needs to start up another external application. I have executables for that external application for different platforms (Win32, PPC and Linux). When the Java application is started it detects the OS and starts up the right executable according to the OS. The executable loads up fine on Windows without any problems. But in both Linux and Max OS X I get this exception:
java.io.IOException: java.io.IOException: "/home/vilas/Documents/Project/build/CLISP/linux/lisp.run": not found
        at java.lang.UNIXProcess.<init>(UNIXProcess.java:143)
        at java.lang.Runtime.execInternal(Native Method)
        at java.lang.Runtime.exec(Runtime.java:566)
        at java.lang.Runtime.exec(Runtime.java:428)
        at jplan.communication.lispserver.LispServer.startupServer(LispServer.java:143)
        at jplan.communication.lispserver.LispServer.run(LispServer.java:109)
        at java.lang.Thread.run(Thread.java:534)lisp.run has all the necessary permissions. If I copy the string (/home/vilas/Documents/Project/build/CLISP/linux/lisp.run) and paste it in a terminal and press enter, the application starts up fine without any problems!! Can you please tell me what could be going wrong?
The following extra information maybe helpfull:
1) I use the exec(String command, String[] envp, File dir) version of exec.
2) The complete format of the command is as follows (one long string):
"/home/vilas/Documents/Project/build/CLISP/linux/lisp.run" -B "/home/vilas/Documents/Project/build/CLISP/linux" -M "/home/vilas/Documents/Project/build/CLISP/linux/lispinit.mem" -i loader.lisp
Thanks in advance for your time and efforts.

I found the problem after extensively searing the forums (looking upto page 4 !! of the results). The problem was that I was using quotes to surround the paths in the command. If you copy and paste it in a terminal it will work fine but it does not work with runtime.exec. I am not sure, but I think the reason is that when a terminal is used, some pre-processing of the commands take place before they are passed onto the OS(shell). But while using runtime.exec, that pre-processing is not peformed and therefore some things will not work.
In order to fix the problem, I use quotes only when the OS is windows. In other cases(OS X, Linux) I escape the spaces i.e. replace " " with "\ ".
PS: The executable is a binary compiled from C code.

Executing bat file without using Runtime.exec()??

Hi all
From my java App ,I am running a bat file. This is what I did:
When I press 'execute' button inside my App, it runs a bat file through Runtime.exec() method. Since exec() runs it through cmd.exe, get a DOS window when I press Execute button. If I manually runs my app from command promt , I dont get it. But I have to create a short cut of my main class in the desktop. This is happening when I run my app from desktop icon.
Now I want to eleminate DOS popup everytime I press execute button. Would anyone pls give an idea how to run bat file without using Runtime.exec()? Any suggestion will be helpful.
Thanks

jscell
Thanks for taking time to answer to my problem .
Here is what my problem: I create a shortcut of my main class in the desktop. Through this shortcut ,I run my java App. My App has a execute button, When I press this button , It run another bat file through Runtime.exec() method, and show some result in the result PAnel. NOw what happen , I get a DOS command window , everytime I press execute button. , Which is very annoying . But If I run my App thorugh command promt by executing: "java myApp", then I dont get this DOS popup. But I have to create a shortcut in the desktop, so other can use it conveniently.
NOw I am not sure why I am getting this DOS window in the middle of my Application. IS it for using Runtime.exec() method? or for running bat file through my application? Can anyone pls tell me? I am kind of new to java, and I am learning lot of stuff from this forum .
Would u pls suggest me about how to eleminate this DOS popup when I press execute button.
Regrds

How to capture output of java files using Runtime.exec

Hi guys,
I'm trying to capture output of java files using Runtime.exec but I don't know how. I keep receiving error message "java.lang.NoClassDefFoundError:" but I don't know how to :(
import java.io.*;
public class CmdExec {
public CmdExec() {
public static void main(String argv[]){
     try {
     String line;
     Runtime rt = Runtime.getRuntime();
     String[] cmd = new String[2];
     cmd[0] = "javac";
     cmd[1] = "I:\\My Documents\\My file\\CSM\\CSM00\\SmartQ\\src\\E.java";
     Process proc = rt.exec(cmd);
     cmd = new String[2];
     cmd[0] = "javac";
     cmd[1] = "I:\\My Documents\\My file\\CSM\\CSM00\\SmartQ\\src\\E";
     proc = rt.exec(cmd);
     //BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
     BufferedReader input = new BufferedReader(new InputStreamReader(proc.getErrorStream()));
     while ((line = input.readLine()) != null) {
        System.out.println(line);
     input.close();
    catch (Exception err) {
     err.printStackTrace();
public class E {
    public static void main(String[] args) {
        System.out.println("hello world!!!!");
}Please help :)

Javapedia: Classpath
How Classes are Found
Setting the class path (Windows)
Setting the class path (Solaris/Linux)
Understanding the Java ClassLoader
java -cp .;<any other directories or jars> YourClassNameYou get a NoClassDefFoundError message because the JVM (Java Virtual Machine) can't find your class. The way to remedy this is to ensure that your class is included in the classpath. The example assumes that you are in the same directory as the class you're trying to run.
javac -classpath .;<any additional jar files or directories> YourClassName.javaYou get a "cannot resolve symbol" message because the compiler can't find your class. The way to remedy this is to ensure that your class is included in the classpath. The example assumes that you are in the same directory as the class you're trying to run.

Parameter to shell script using Runtime.exec(string)

Hi all, ( Speciall hi to dheeraj tak )
Briefly : How do i pass an arguement to a non - java executible being called using Runtime.exec.
In detail : i am using Runtime.exec to call a shell script : The code is as follows:
String callAndArgs[] = {"/home/tom/jakarta-tomcat-4.1.24/webapps/dash/script.sh"};
try {
Runtime rt = Runtime.getRuntime();
Process child = rt.exec(callAndArgs);
This works properly & calls the shell script which in turn invokes some other executible (c file).
$HOME/midi/test/build/bin/<C-EXECUTIBLE>
Here i am specifying the name (say hello.exe ) . So far so good.
I want to make this happen dynamiclaly. so i need to pass the name of the executible as a parameter to the script.
To pass a parameter i hav to change the string to :-
String callAndArgs[] = {"/home/tom/jakarta-tomcat-4.1.24/webapps/dash/script.sh <C-EXECUTIBLE HERE>"};
and the script to
$HOME/midi/test/build/bin/$1 --- where $1 refers to argument 1. (C-EXECUTIBLE AGAIN).
This is giving an IO - Execption. Plz help
Code will be very helpful.
Thanx in advance

some 1 plz tell me the difference :-
This is the documentation of Runtime.exec that i found :-
1> exec
public Process exec(String command) throws IOException
Executes the specified string command in a separate process.
The command argument is parsed into tokens and then executed as a command in a separate process. This method has exactly the same effect as exec(command, null).
Parameters:
command - a specified system command
Complete refernce says : Process (String progName) ----- Executes a program specified by programname as a seperate process.
2> exec
public Process exec(String cmdarray[]) throws IOException
Executes the specified command and arguments in a separate process.
The command specified by the tokens in cmdarray is executed as a command in a separate process. This has exactly the same effect as exec(cmdarray, null).
Parameters:
cmdarray - array containing the command to call and its arguments.
Complete reference says : Process exec(String comLineArray[]) ---- Executes the command line specified bythe string in comLineArray as a seperate process.
This means that there is provision 4 command line arguments...
how do u use it then????????????????????????????

How to run db2 command by using Runtime exec

Hello
I am using java. When i am runing db2 command by using Runtime.exec( String cmd, String[] env ). I gave the environment path
DB2CLP=6259901
DB2DRIVER=D:\ibm\db2\java\db2java.zip
DB2HOME=D:\ibm\db2
DB2INSTANCE=DB2
DB2MMTOP=D:\CMBISS
but still I am getting error message
"DB21061E Command line environment not initialized"
after setting the above path in the cmd It is working fine. When i am trying thro java programm i am getting the above error. Can I get answer for this.
bhaski.

Before you can execute DB2 commands you have to open a DB2 CLP. The following code will do so:
import java.io.IOException;
public class Db2 {
     public static void main(String args[]) {
          try {
               Runtime rt = Runtime.getRuntime();
               Process child = rt.exec("db2cmd");
               child.waitFor();
          catch (IOException io) {
               io.printStackTrace();
          catch (InterruptedException e) {
               e.printStackTrace();

Using runtime.exec,process streams

Hi all,
I am using runtime.exec to execute a batch file(rmdir /s/q directoryname) which deletes all the files in a certain directory(including subdirectories). However, some of the files are not deleted since they are being used by other processes.
I have closed all file references but still the batch file says they are being used by other processes. The File.canWrite() method however, returns true for all the files. I have also tried to delete the files using file.delete but it does not work.
So I have 2 questions.
1. Can I forcibly delete these files some other way.
2. If i call a batch file to delete the files and it fails on some files, the command window displays "cannot delete files". How can I write out thse messages into a text file which i can use as a log file.Do I have to use Process.getInputstream()/Process.getInputstream() ? If so, how?
Thanks for your help.
Vinny

I tried the following before but the string i get is always empty, but i can see there are messages in the command window. Please let me now if i am doing something wrong.
try{
Process p = rt.exec("cmd.exe /c start deletefiles.bat");
InputStream ins = p.getInputStream();
byte[] bytearray = new byte[1024];
int bytecount;
String dos_string="";
BufferedInputStream bis = new BufferedInputStream(ins);
while ((bytecount = bis.read(bytearray, 0, 1024)) > -1) {
String str = new String(bytearray,0,bytecount);
dos_string += str;
System.out.println("dos string is" +dos_string);
catch (Exception e) {
System.out.println("Error: " + e);

Using Runtime.exec to execute a C++ executable

Hello,
I would like to know if it possible to execute a C++ executable using Runtime.exec() and wait for it to complete and how do I read back the output file created by the C++ executable into the Java Code?
TIA.
RHP

When I execute the code with Runtime.exec(), and read
from the Process's inputStream I am ablt to view the
cout from the C++ code. But the output file that has
to be created by the C++ code is not created,Then this is maybe an error in the C++ code? Maybe you don't have permissions to create that file where you want to.
where
would the output from the C++ code go to when I use a
ofstream in my C++ code andIf you create the file stream in C++ with an absolute file name then the output goes into that file. If it's a relative file name, then the basis is most likely the current working directory (found in the system property "user.dir" if you used one of Runtime's methods without the File argument, otherwise it's the directory you provide.
How do I read both streams
from the Java Code?You create an FileInputStream and - if you want to read character instead of binary data - on top of that an InputStreamReader. You might add a BufferedReader on top of that if you want to read line by line.
does that answer your questions?
robert

Using runtime.exec to zip some files

Hi,
I am using runtime.exec to try to automatically zip a bunch of files on a server. However, it does not seem to be working.
Before I execute the command, I save the zip command in a string. I then print the string to a log file, and then execute the runtime zip command. But nothing happens.
Yet, when I copy the string from the log, and paste it in a terminal, it properly creates the zip files. So, I know I have the correct command string, it just does not seem to be working within the java application. Also, the command string uses fully qualified directories, so it is not a directory issue.
I am using ubuntu linux.
Any ideas?
-Adam

adamSpline wrote:
Hi,
I am using runtime.exec to try to automatically zip a bunch of files on a server. However, it does not seem to be working.
Before I execute the command, I save the zip command in a string. I then print the string to a log file, and then execute the runtime zip command. But nothing happens. Within Runtime.exec() any command does not run in a shell and I bet you use wild cards and/or other commands to be interpreted by a shell which will not be interpreted since there is no shell. And, since you don't mention error messages or the return code, I will also bet you don't process the Process stdout , stderr and the return code properly.
It looks to me like you have fallen for at least two for the traps in [http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html|http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html].
>
Yet, when I copy the string from the log, and paste it in a terminal, it properly creates the zip files. So, I know I have the correct command string, it just does not seem to be working within the java application. Also, the command string uses fully qualified directories, so it is not a directory issue.
I am using ubuntu linux.
Any ideas?I agree with 'masijade' - use the built in Java classes.
>
-Adam

Using Runtime exec() to open java on other directory

HI, I have a little problem and i hope everyone can help me out abit. You see when u use Runtime.exec(), how to you use it so that when the file you want to open is different from your program directory.
For example,
my program is in c:\windows\desktop
but the file i want to open eg. Somthing.class is in c:\my documents\
How do I open it using java and i wish to open the file using the java command. Thank a million

Runtime.getRuntime().exec("cmd /c start /d\"C:\\my documents\" java.exe Somthing");
Can someone explain the /c start /d\"C:\Mydocuments\" java.exe Somthing.
And I try to use ping in RunTime.exec,how do I construct the string?And how do i get the result of the ping?
Thanks

Launching another VM instance using Runtime.exec()

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