How to start an executable program from a java program ?

Hi,
does someone know how to start an executable program from a JAVA program ?
Thanks, Fred.

Take a look at the Runtime class.
-S-

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How to display a oracle table from a java program?

How to display a oracle table from a java program.
Hello friends, I have written a Java program, using oracle 10g as backend.
I want to display a oracle table as output. Im not getting how to display oracle table as a output table.. Pls help me
Thank you

jayanthds, you're not going to get a satisfactory
answer to this here. it's too big a task to justbe
quickly outlined in a forum - the reply "all youneed
to do is to query you table and return it asJTable"
is worthless, for example, since the solution to
any problem can be distilled to such a
soundbite, if need be. doesn't make the solutionany
simpler
essentially you're asking "how do I write adatabase
application?". all you'll get is snippets of code
that, when fitted together, will eventually helpyou
do this, but you'll spend days and days comingback
saying "right, I've done that, now what?" until
either you or the forum gets frustrated with the
whole affair and the process stops
there are entire books written about this subject,
and countless tutorials and guides on theinternet.
you're better off going down that routehehehe.well, it's true! I used to have a manager that would outline the solution to a problem in a few lines of pseudocode, and then firmly believe that the actual solution would be just as brief and simple. shame his pseudocode included such lofty abstractions as "reformat all data"

How to run a openssl command from a java program

Hi All
Please suggest on how to run a openssl command from a java program.
I am using this
Runtime runtime = Runtime.getRuntime();
runtime.exec("openssl pkcs8 -inform der -nocrypt test.der result.pem");
This is suppose to take test.der as input and create result.pem.
There are no errors but the file result.pem isnt created.
Thanks in Advance

First off is that openssl command correct? Should it be this instead:
openssl pkcs8 -inform der -nocrypt -in test.der -out result.pem
Try out your openssl command within a command prompt so that you know that it works ok. I think the command line you specified waits on stdin (well it does for me).
After that.....
runtime.exec creates a Process object. If you do this:
Process openssl = runtime.exec("....")
then you can examine the return code from openssl to see the exit code - for instance if the input file does not exist then exit = 1. You can test for this with Java
Alternatively you could get the stderr from the process and look inside it - if it is 0 length then all is good, if it has some text in there then it has likely failed. You could then throw an exception and include the stderr output in the exception messgae. You may need to experiment with this, runnig it first when openssl is happy then running it again when openssl is upset.
M

How to call j2me emulator instance from a java program?

hi,
how to call j2me emulator instance from a java program?
i tried public void startApp(){
try{
platformRequest("tel:+5550000");
}catch(Exception e){
e.printStackTrace();
from a j2me midlet itself,
but it gave illegal access exception.
do i need any hardware phone connected to my pc?
please help.

http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
import java.util.*;
public class OpenExplorer{
public static void main(String args[]){
     new OpenExplorer();
public OpenExplorer(){
     try{
     String command = "explorer C:";
     // or String command = "cmd /c explorer C:";
     Runtime runtime = Runtime.getRuntime();
     Process process = runtime.exec(command);
     int exitVal = process.waitFor();
     System.out.println("Exit Value: " + exitVal);
     } catch(Exception e){
     e.printStackTrace();
}

How to run a cygwin.bat from a java program?

Can you please let me know how to run a cygwin.bat file from a java program and to give commands through java program. I have a program to run .exe files, but when I do the same for the cygwin.bat it doesnt work. In task mgr a BASH and a cmd.exe is running. Please help me on this & bit urgent. Thanks in advance!

Can you please let me know how to run a cygwin.bat
file from a java program and to give commands through
java program. I have a program to run .exe files, but
when I do the same for the cygwin.bat it doesnt work.Of course not. .bat files are no native executables. You need to open a shell first, like "cmd /c cygwin.bat ..."
& bit urgent. Thanks in advance!If I had read this earlier I wouldn't have replied. Why exactly is your time worth more than anybody else's?

How can I pass system commands from a java program? Urgent!

hi,
I have been trying this out since a long time. How do I send system commands to command.com or cmd.exe from a java program and an output of the executed command back to the java application.
If u have any idea, or have any information about the kind os application reply back.
Thanks
Deepa Datar

This is the code which I tried, but it displays only the title of MS-DOS, something like " Microsoft Corp...etc ". But doesn't take any input, and the subprocess(cmd.exe) hangs.
import java.io.*;
public class cmddemo2
public static void main(String arg[])
try
System.out.println("cmd");
Process p=Runtime.getRuntime().exec("cmd.exe");
DataInputStream din=new DataInputStream(p.getInputStream());
DataOutputStream dout=new DataOutputStream(p.getOutputStream());
System.out.println("after streams");
String s;
dout.writeChars("type cmddemo2.java");
while((s=din.readLine())!="\n")
System.out.println(s);
dout.writeChars("dir");
String s1;
while((s1=din.readLine())!="\n")
System.out.println(s1);
System.out.println("over");
catch(Exception e)
{ System.out.println("Exception : "+e);

Please help with executing a java program from another java program

Hi, I have tried to execute a very simple java program which is printed out "Hello world" from another java gui program when the user click on the "START" button. However, I don't receive any print out on the terminal when they click it. These two programs are being developed in Unix environment. Here is the code that I am trying to use.
Runtime r = Runtime.getRuntime();
r.exec("java HelloWorld");
p.s. HelloWorld is java class of the HelloWorld.java

I think you have to luanch your MS Prompt first before executing the command.

How to create windows executable file from a java file. Please help.

Hi,
For my project I developed the codes in Java. It is working well with java run time environment. But without that I can not run it. I need to create a exe file (windows executable file) from the java source code. If you have any idea please share it with me.
Even if you know it very lightly, please help with what you know. That would be a big help for me.
Thank you very much.

Does anybody know how to read a manual?
Matt Richardson
Certified LabVIEW Developer
MSR Consulting, LLC

How to open my computer window from a java program.....

To open my computer window in win xp is simple from the start menu.
i want to open it from a java program .
any idea to open my computer from a java program or command prompt......

http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
import java.util.*;
public class OpenExplorer{
public static void main(String args[]){
     new OpenExplorer();
public OpenExplorer(){
     try{
     String command = "explorer C:";
     // or String command = "cmd /c explorer C:";
     Runtime runtime = Runtime.getRuntime();
     Process process = runtime.exec(command);
     int exitVal = process.waitFor();
     System.out.println("Exit Value: " + exitVal);
     } catch(Exception e){
     e.printStackTrace();
}

How to read files on server from a java program?

Hello,
I am fairly new to JSP programming. I have an issue with reading files. I am trying to call method of a normal java file from a jsp program. The method I am trying to call does some IO operation on Files. I have the files in the same directory as my class files on server that is in WEB-INF/classes folder. In my java program, I am giving just the file name to open because the files and the classes are in the same directory. But this is not working.
What exactly should I do to read a file from a java program, that is running on the server?
Any help is appreciated.
Thanks,
Krishna

String realFilePath = application.getRealPath("/WEB-INF/myFile.txt");
File fileToOpen = new File(realFilePath);
out.println(fileToOpen.getAbsolutePath() + ": exists? " + fileToOpen.exists());in this case "application" is a reference to the ServletContext.
It is an implicit variable in a JSP. In a servlet:
ServletContext application = getServletConfig().getServletContext();

How to list all OS processes from a java program

I want to list/kill all OS processes from a java program, or a part from all processes according to a filter on a name of process.
a similar functionality is ps in Unix or taskkill in Windows XP.
Thanks!

Hi,
I was looking for such lib, but finally I decided to accomplish the job with my fingers end ;-). It maigh be helful for u guys:
// is written for x based OSs
private static void killProcess(Process process) {
if (process == null)
return;
process.destroy();
private static void closeProcessStreams(Process process) {
try {
process.getErrorStream().close();
} catch (IOException eyeOhEx) {
private static void listPHPs() {
Process proc = null;
Runtime rt = Runtime.getRuntime();
int exitVal = 0;
try {
proc = rt.exec(" ps -C php"); // here use ur filter. issue "man ps" in linux for more info
catch (Exception ex) {
System.out.println(ex.getMessage());
killProcess(proc);
return;
try {
// process the return list of ur command
InputStream stdReturnStr = proc.getInputStream();
InputStreamReader isr = new InputStreamReader(stdReturnStr);
BufferedReader br = new BufferedReader(isr);
String line = null;
String returnMsg = "";
boolean firstLine = true;
int[] allPIDs = new int[100]; // finally we have an array of PIDs
int PIDCount = 0;
while ( (line = br.readLine()) != null) {
if (!firstLine){ // the first line is title, ignore it
returnMsg += line + "\n";
String PID = line.trim().split(" ")[0];
System.out.println(PID);
try{
allPIDs[PIDCount] = Integer.parseInt(PID);
PIDCount++;
}catch(Exception ex){
else
firstLine = false;
System.out.println(returnMsg);
catch (Exception t) {
System.out.println(t.getMessage());
killProcess(proc);
return;
try {
exitVal = proc.waitFor();
catch (Exception t) {
System.out.println(t.getMessage());
killProcess(proc);
return;
closeProcessStreams(proc);
Thats it!

Compiling Java program from other java program

Hi,
How can I compile and capture the compilation result from another java program?
Thanks

As if I had seen somewhere a hint about being able to
programatically compile with the help of the class
sun/tools/javac/Main found in the tools.jar.I saw that article, too, but when I took a look at the JDK's source code, it became apparent that none of the classes in tools.jar are supported. Your program could break with any new version of the JDK.
If you're still interested, here's the URL:
http://java.sun.com/developer/JDCTechTips/2003/tt0722.html

How to Create Linux-Cron Job from a Java Program

Hello,
Can anybody help me to CREATE/EDIT/DELETE Linux Cron job from Java Program. Its Very Urgent.Thanks in advance..
from
Chakri

I decided this didn't sound too tough so I played around with it a little. Basically because I'd never tried executing external processes out of java before, so I wanted to see how it was done.
Just change whatever you like in the jobs ArrayList and call writeJobs.
If you call writeJobs without putting anything in the list first you'll wipe out all of your crontab entries.
import java.lang.*;
import java.io.*;
import java.util.*;
public class cron {
    ArrayList jobs;
    Runtime rt;
    cron() {
     rt = Runtime.getRuntime();
     jobs = new ArrayList();
    void readCron() {
     String[] list = { "crontab", "-l" };
     jobs = new ArrayList();
     try {
         // Stick a job into crontab
         Process child = rt.exec(list);
         BufferedReader cronout = new BufferedReader(new InputStreamReader(child.getInputStream()));
         String cronjob = cronout.readLine();
         while (cronjob != null) {
          jobs.add(cronjob);
          cronjob = cronout.readLine();
         child.waitFor();
     catch(IOException e) {
         System.err.println("IOException starting process!");
     catch(InterruptedException e) {
         System.err.println("Interrupted waiting for process!");
    void listJobs() {
     Iterator iter = jobs.iterator();
     while (iter.hasNext()) {
         System.out.println((String)iter.next());
    void writeJobs() {
     String[] edit = { "crontab"};
     try {
         // Stick a job into crontab
         Process child = rt.exec(edit);
         PrintWriter cronIn = new PrintWriter(child.getOutputStream());
         Iterator iter = jobs.iterator();
         while (iter.hasNext()) {
          cronIn.println((String)iter.next());
         cronIn.close();
         child.waitFor();
     catch(IOException e) {
         System.err.println("IOException starting process!");
     catch(InterruptedException e) {
         System.err.println("Interrupted waiting for process!");
    void doStuff() {
     readCron();
     listJobs();
     jobs.add("* * * * 4 cronjob");
     writeJobs();
     readCron();
     listJobs();
    public static void main(String[] args) {
     cron c = new cron();
     c.doStuff();
}

How to submit a HTTP Request from a Java Program

I am working on an web based application where in I need to submit the HttpRequest through a Java Program and not through browser. Moreover my intent is just to submit the HttpRequest. I donot want to wait for the response to come back. I have used the URL Connection class to do the same and I am trying to post this request. The contents of the methods that I am using are as below:-
public void doPost(URL url, String inputXMLString) throws IOException
          //Create URLConnection based on the passed URL
          URLConnection connection = url.openConnection();
          connection.setDoOutput(true);
          connection.setDoInput(false);
          connection.setUseCaches(false);
          connection.setAllowUserInteraction(false);
          connection.setRequestProperty("Content-type", "application/x-www-form-
urlencoded");
          //Get the Connection's output stream and write the request to it.
          PrintWriter out = new PrintWriter(connection.getOutputStream());
          out.print("&ena-request-input=" + URLEncoder.encode(inputXMLString));
          out.flush();
          out.close();
Call to the above method does not invoke the URL I am intending to submit the request at.
Can anybody give me the clue....................................................?

I agree with the advice to launch a new thread to read and ignore the response. I don't think you should have to do it to make it work, but it's worth trying for two reasons:
1) If it turns out it does make it work, well, then either you can leave it that way, or use that as a clue to help figure out how to make it work the way you want.
2) There may be an error message there that will give you an idea why it's not working.
When you say it's not invoking the servlet, what does that mean, and how do you know? Is it just that the final results aren't being seen? Put a bunch of logging statements in the servlet. It could be that it's getting hit, but you're corrupting the string you're building, or sending some extra junk that it can't handle. Spit out a log statement from the start of doPost, to see if it's even getting there. Then log the parameter. Enclose the output in quotes or braces or something to make sure there's not extra junk. I've had XML docs not parse because there was a blank line at the beginning.
If it works in the browser but not from your standalone app, then you need to have the servlet tell what difference it sees in the two cases. Print out headers, other params, everything you can think of.
Re-read the docs for URL, HttpURL, whatever, to make sure you're doing all the right steps in the right order. Make a servlet that just takes a single, simple param=value via POST and see if you can get that to work.

Execute compiler from my java program??

Hi,
How can I call java compiler and interpreter from my own java program?? I've tried this code :
public static void main(String[] args) {
    try {
        Runtime r = Runtime.getRuntime();
        r.exec("javac Test.java");
    } catch (Exception err) {
        err.printStackTrace();
}but it didn't work. An exception was thrown, it sounds something like "error javac=2", or something like that. The exception was thrown on line r.exec. I tried change the command with r.exec("java -version"). But nothing happenned (I thought I will get string with my java version on it, like when I type the same command on console), but no error was thrown too. But when I tried this one : r.exec("java Test"), the exception was thrown. What's going on? I've compiled the Test.java using NetBeans, and moved the Test.class into user folder (C:\Document And settings\Timotius Pamungkas), but get the same exception. I've already set the path and classpath. But when I tried r.exec("calc"), windows calculator appeared.
What's going on?? How can i compile java source code from and execute the calss file or jar file my own java program?

Read this:
When Runtime Exec Won't

How to start an executable program from a java program ?

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