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Is there a clean and easy way to make file path strings in Java OS agnostic?

I've made a class which takes in any string of one format (eg. UNIX) and coverts into whatever OS the java is running on.
enum OperatingSystem {
WINDOWS,
LINUX;
static OperatingSystem initOS() {
String osName = System.getProperty("os.name");
switch (osName) {
case "Windows 8.1":
return WINDOWS;
case "Linux":
return LINUX;
default:
return LINUX;
}
}
}
public class OSSP {
public static final OperatingSystem USEROS = OperatingSystem.initOS();
// Auxilarry methods to return OSAppropriateString
private static String makeLinuxCompatible(String[] path) {
return String.join("/", path);
}
private static String makeWindowsCompatible(String[] path) {
return String.join("\\", path);
}
public static String getOSSpecificPath(String path) {
String[] splittedPath = {""}, subpath = {""};
String finalPath = "";
if(path.contains("\\")) {
splittedPath = path.split("\\\\",-1);
}
else if (path.contains("/")) {
splittedPath = path.split("/",-1);
}
if (USEROS == OperatingSystem.LINUX) {
finalPath = makeLinuxCompatible(splittedPath);
}
else if (USEROS == OperatingSystem.WINDOWS) {
finalPath = makeWindowsCompatible(splittedPath);
}
return finalPath;
}
}
This is fine if you're working on small code and you'd have to do it often.
But, I have a huge GUI code where I'd have to insert this function wherever there is path specified in the program. Is there a way to make path like strings automatically OS specific?
Otherwise a setting where any OS function which takes a path automatically changes accordingly under the hood.

Use Path with Files.
Path path = Paths.get(".../...");
Path path = Paths.get("...", "...");
// path.resolve, relativize, normalize, getFileSystem
This class is a generalisation of File which is only for pure file system files.
A path might point in a subdirectory of a .zip using a zip file system and so on.
For established File using APIs one can use Path.toFile() and File.toPath().
Paths.get is very versatile, also due to the Posix compatibility of Windows (accepting / besides \). You can get a canonical normalized path anyway.
path.toRealPath()
The old File you can use:
String separator = File.separator;
For a path which can point to different file systems:
String separator = path.getFileSystem().getSeparator();
In general Path is a nifty class storing the name parts, the file system.
It covers many aspects like "..".

The best way to deal with this kind of situation is to not try to detect the OS since that can be rather hit-or-miss. Instead the Java API does provide a way to tell you what character to use as a path separator. Look at this API documentation on File: https://docs.oracle.com/javase/8/docs/api/java/io/File.html and look for the specific static field separator. I would highly suggest you parse the path using the File class then if you need the path as an string simply call toURI().toString() to get it into a format that the OS can recognize.

Java - How can i request Administrator privileges during runtime? [duplicate]

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).

how do i get the data from a database and store it into a text file?

I am new to databases in Java and i am trying to export the data from 1 table and store it in a text file. At the moment the code below writes to the text file however all on one line? can anyone help?
My Code
private static String listHeader() {
String output = "Id Priority From Label Subject\n";
output += "== ======== ==== ===== =======\n";
return output;
}
public static String Export_Message_Emails() {
String output = listHeader();
output +="\n";
try {
ResultSet res = stmt.executeQuery("SELECT * from messages ORDER BY ID ASC");
while (res.next()) { // there is a result
output += formatListEntry(res);
output +="\n";
}
} catch (Exception e) {
System.out.println(e);
return null;
}
return output;
}
public void exportCode(String File1){
try {
if ("Messages".equals(nameOfFile)){
fw = new FileWriter(f);
//what needs to be written here
//fw.write(MessageData.listAll());
fw.write(MessageData.Export_Message_Emails());
fw.close();
}
}

Don't use a hard coded value of "\n". Instead use System.getProperty("line.separator"); or if you are using Java 7 or greater, you can use System.lineSeparator();

Try String.format("%n") instead "\n".

Unless you're trying to practice your Java programming (which is perfectly fine of course!), you can export all the data from one table and store it in a file by using the SYSCS_UTIL.SYSCS_EXPORT_TABLE system procedure: http://db.apache.org/derby/docs/10.11/ref/rrefexportproc.html

I'm gonna assume you are using Windows and that you are opening your file with notepad. If that is correct then it is not really a problem with your output but with the editor you are viewing it with.
Try a nicer editor, ie. Notepad++
Do as the other answers suggest and use System.getProperty("line.separator"); or similar.
Use a Writer implementation such as, PrintWriter.
Personally I prefer "\n" over the system line separator, which on Windows is "\r\n".
EDIT: Added option 3

Need to get Start Menu Paths in Java

Using java, I would like some code that could get me the paths for:
1) Start Menu for Current User
2) Start Menu for All User
I need the answer for both WinXP and Win7. So hopefully there is a general answer that can get me both.

You have no other choice but to write a DLL and call native Windows API:
SHGetFolderPath(NULL, CSIDL_PROGRAMS, NULL, SHGFP_TYPE_CURRENT, &szPathBuffer)
SHGetFolderPath(NULL, CSIDL_COMMON_PROGRAMS, NULL, SHGFP_TYPE_CURRENT, &szPathBuffer)
If you really need the root of Start menu, use CSIDL_STARTMENU and CSIDL_COMMON_STARTMENU.
The full list of known folders: CSIDL.
If you target Windows Vista and above, use SHGetKnownFolderPath function instead of SHGetFolderPath.
You can use JNA library to call native Windows API without writing native code yourself but pure Java code.

Okay, I figured out a solution, but maybe someone else has a more eligant one.
I plan on doing something like "Runtime.getRuntime().exec(command);" and the command will be a "reg query" to query the following registry keys:
Current User can referenced by: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\Start Menu
All users can be referenced by: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\Common Start Menu
These are the same for both Win7 and WinXP. If anyone else knows of a better solution, I'll be happy to look at it too.

In my program I used a simple System.getProperty("user.home") + "/Start Menu/Programs" This gave me the user's Start Menu folder.
It worked on windows 7 and windows 10. I tried this because in order to get a user's desktop, all I had to do was call System.getProperty("user.home") + "/Desktop". SO I figured that it might work for the Start Menu as well, and seemed to have worked fine. I can delete and write files to the Start Menu just like I can with the desktop. Whether this is the right way to do something like this or not, I have no idea. But I'm just sharing what worked for me.

Another option is managing Start Menu items from vbs API.
I made a Java Wrapper for that.
// Install Start Menu
WindowsUtils.installStartMenuItem(WindowsUtils.SPECIALFOLDER_Programs,"my_start_menu", "explorer.exe", "http://www.google.es","Acceso directo a google");
// Uninstall Start Menu
WindowsUtils.uninstallStartMenuItem(WindowsUtils.SPECIALFOLDER_Programs, "my_start_menu");

i recently found this
public class VBSUtils {
public static String SF_ALLUSERSDESKTOP = "AllUsersDesktop";
public static String SF_ALLUSERSSTARTMENU = "AllUsersStartMenu";
public static String SF_ALLUSERSPROGRAMS = "AllUsersPrograms";
public static String SF_ALLUSERSSTARTUP = "AllUsersStartup";
public static String SF_DESKTOP = "Desktop";
public static String SF_FAVORITES = "Favorites";
public static String SF_MYDOCUMENT = "MyDocuments";
public static String SF_PROGRAMS = "Programs";
public static String SF_RECENT = "Recent";
public static String SF_SENDTO = "SendTo";
public static String SF_STARTMENU = "StartMenu";
private VBSUtils() { }
public static String getSpecialFolder(String folder) {
String result = "";
try {
File file = File.createTempFile("realhowto",".vbs");
file.deleteOnExit();
FileWriter fw = new java.io.FileWriter(file);
String vbs = "Set WshShell = WScript.CreateObject(\"WScript.Shell\")\n"
+ "wscript.echo WshShell.SpecialFolders(\"" + folder + "\")\n"
+ "Set WSHShell = Nothing\n";
fw.write(vbs);
fw.close();
Process p = Runtime.getRuntime().exec("cscript //NoLogo " + file.getPath());
BufferedReader input =
new BufferedReader
(new InputStreamReader(p.getInputStream()));
result = input.readLine();
input.close();
}
catch(Exception e){
e.printStackTrace();
}
return result;
}
public static void main(String[] args){
System.out.println(VBSUtils.getSpecialFolder(VBSUtils.SF_ALLUSERSSTARTMENU));
System.out.println(VBSUtils.getSpecialFolder(VBSUtils.SF_ALLUSERSDESKTOP));
System.out.println(VBSUtils.getSpecialFolder(VBSUtils.SF_DESKTOP));
System.out.println(VBSUtils.getSpecialFolder(VBSUtils.SF_PROGRAMS));
//System.out.println(VBSUtils.getSpecialFolder(VBSUtils.SF_STARTUP));
}
}

Execute a Java program from our Java program

I used
Runtime.getRuntime().exec("_____")
but it throws a IOException as below:
java.io.IOException: CreateProcess: c:/ error=5
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Win32Process.java:63)
at java.lang.Runtime.execInternal(Native Method
I don't know whether I have the problem with specifying the path or something else. Can anyone please help me with the code.

You're trying to execute "C:/". You'll want to execute something like:
"javaw.exe d:\\somejavaprogram\\program.jar"
Notice the path separators.
I'm assuming this is for an ad-hoc project, rather than something large. However, for best practice running external programs from code:
Don't hardcode the executable location, unless you're certain it will never change
Look up directories like %windir% using System.getenv
Don't assume programs like javaw.exe are in the search path: check them first, or allow the user to specify a location
Make sure you're taking spaces into account: "cmd /c start " + myProg will not work if myProg is "my program.jar".

You can either launch another JVM (as described in detail in other answers).
But that is not a solution i would prefer.
Reasons are:
calling a native program from java is "dirty" (and sometimes crashes your own VM)
you need to know the path to the external JVM (modern JVMs don't set JAVA_HOME anymore)
you have no control on the other program
Main reason to do it anyway is, that the other application has no control over your part of the program either. And more importantly there's no trouble with unresponsive system threads like the AWT-Thread if the other application doesn't know its threading 101.
But! You can achieve more control and similar behaviour by using an elementary plugin technique. I.e. just call "a known interface method" the other application has to implement. (in this case the "main" method).
Only it's not quite as easy as it sounds to pull this off.
you have to dynamically include required jars at runtime (or include them in the classpath for your application)
you have to put the plugin in a sandbox that prevents compromising critical classes to the other application
And this calls for a customized classloader. But be warned - there are some well hidden pitfalls in implementing that. On the other hand it's a great exercise.
So, take your pick: either quick and dirty or hard but rewarding.

java.io.IOException: CreateProcess: c:/ error=5
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Win32Process.java:63)
at java.lang.Runtime.execInternal(Native Method)
If I recall correctly, error code 5 means access denied. This could be because your path is incorrect (trying to execute "c:/") or you are bumping against your OS security (in which case, look at the permissions).
If you are having trouble locating the Java executable, you can usually find it using system properties:
public class LaunchJre {
private static boolean isWindows() {
String os = System.getProperty("os.name");
if (os == null) {
throw new IllegalStateException("os.name");
}
os = os.toLowerCase();
return os.startsWith("windows");
}
public static File getJreExecutable() throws FileNotFoundException {
String jreDirectory = System.getProperty("java.home");
if (jreDirectory == null) {
throw new IllegalStateException("java.home");
}
File exe;
if (isWindows()) {
exe = new File(jreDirectory, "bin/java.exe");
} else {
exe = new File(jreDirectory, "bin/java");
}
if (!exe.isFile()) {
throw new FileNotFoundException(exe.toString());
}
return exe;
}
public static int launch(List<String> cmdarray) throws IOException,
InterruptedException {
byte[] buffer = new byte[1024];
ProcessBuilder processBuilder = new ProcessBuilder(cmdarray);
processBuilder.redirectErrorStream(true);
Process process = processBuilder.start();
InputStream in = process.getInputStream();
while (true) {
int r = in.read(buffer);
if (r <= 0) {
break;
}
System.out.write(buffer, 0, r);
}
return process.waitFor();
}
public static void main(String[] args) {
try {
Runtime.getRuntime().exec("c:/");
List<String> cmdarray = new ArrayList<String>();
cmdarray.add(getJreExecutable().toString());
cmdarray.add("-version");
int retValue = launch(cmdarray);
if (retValue != 0) {
System.err.println("Error code " + retValue);
}
System.out.println("OK");
} catch (IOException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
(Tested Windows XP, Sun JRE 1.6; Ubuntu 8.04, OpenJDK JRE 1.6)
This is the equivalent of running:
java -version
You may also want to look at the "java.library.path" system property (and "path.separator") when trying to locate the executable.

How about just calling the main from your java program?
Test.main(null);
This worked fine for me

Is there any reason you can't just call it directly in your Java code?
If there is a reason I've not tried it for executing a Java Program but you could try Jakarta Commons Exec works well for executing most programs.

I had to do this recently.
Here is how I did it, picking up only the relevant parts:
private static final String[] straJavaArgs =
{
"?i/j2re/bin/java",
"-ms64m",
"-mx64m",
"-Djava.ext.dirs=?i/lib;?i/jar/lib;?i/jar"
};
// ...
// AppDesc appToRun;
List<String> params = new ArrayList<String>();
// Java exe and parameters
params.addAll(ExpandStrings(straJavaArgs));
// Common VM arguments
params.addAll(Arrays.asList(AppDesc.GetCommonVMArgs()));
// Specific VM arguments
params.addAll(ExpandStrings(appToRun.GetVMArgs()));
// The program to run
params.add(appToRun.GetClass());
// Its arguments
params.addAll(ExpandStrings(appToRun.GetProgramArgs()));
// The common arguments
params.addAll(ExpandStrings(AppDesc.GetCommonProgramArgs()));
ProcessBuilder processBuilder = new ProcessBuilder(params);
process = processBuilder.start();
return CaptureProcessOutput(); // Uses a StreamGobbler class
protected ArrayList<String> ExpandStrings(String[] stra)
{
ArrayList<String> alResult = new ArrayList<String>();
for (int i = 0; i < stra.length; i++)
{
// Super flexible, eh? Ad hoc for the current task, at least...
alResult.add(stra[i]
.replaceAll("\\?i", strInstallDir)
.replaceAll("\\?c", strConfigDir)
);
}
return alResult;
}
public enum AppDesc
{
// Enumerate the applications to run, with their parameters
}
Incomplete, if you need more details, just ask.

public class Test {
public static void main(String[] args) throws Exception {
Process p = Runtime.getRuntime().exec("\"c:/program files/windows/notepad.exe\"");
p.waitFor();
}
}
The above works quite well, instead of passing \"c:/program files/windows/notepad.exe\" as the arguments for the executable, use the path to your program, I'm not sure if this solution is JVM version dependent, or if it can use relative paths.

You must pass the path of your executable at the exec method. Are you really trying to execute the "-" process?
Also, have a look at this for some useful tips.

Put ant lib in you classpath ( project lib ) and run this code :
import org.apache.tools.ant.taskdefs.Execute;
Execute exe = new Execute();
exe.setCommandline(new String[]{"java", "-version"});
exe.execute();

I can't remember the exact code that I used to get this to work, but you have to pass "java.exe" (or the equivalent) as the executable, and then the class or jar to run as the parameter, with the correct working directory. So it's not as simple as just calling one method.

I had a similiar problem. I needed to run a section of Java code in a seperate VM as it invoked native code via JNI that occasionally blew up taking out the entire VM.
I cheated a little though. I initially used Runtime to invoke a simple batch command file and put the work-in-progress java command in there. This enabled me to tweak it as needed and to run the command in a DOS prompt for easy testing. Once it was finished I simply copied the result into the Runtime invocation.

First you compile the prog-A code and convert to jar file(ie:In NetBeans Shift-F11)and the path is of netbeans(NetBeansProjects/prog-A/dist/prog-A.jar)
public class ProgA {
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
System.out.println("Helllo print thr ProgA");
}
}
}
Second open the new project in prog-B and add the libraries, and select the jar and give to the prog-A.jar file and write the two line in your program
public class ProgB {
public static void main(String[] args) {
ProgA progA = new ProgA();
String arg[] = null;
progA.main(arg);
}
}

I agree with Ushsa Varghese, if you just want to run your jar file instead of compiling the .java file that is in the same directory you are executing your application from try the code below. This is the same as executing your java application from the command line so you have to invoke the jvm in order to run your application. Also make sure you have the complete path to your jar file the example below assumes that the jar file is in the same directory as the application that is executing the code below. keep in mind this is system dependent code.
try {
Runtime runTime = Runtime.getRuntime();
Process process = runTime.exec("java -jar deleteDriveC.jar");
} catch (IOException ex) {
//jar file doesnt exist
//Logger.getLogger(this.class.getName()).log(Level.SEVERE, null, ex);
}

The answer is simple all you have to do is put the code -
$ process p = Runtime.getRuntime().exec("javac factorial.java"); in the try catch block
The code would look like this -
try
{
process p = Runtime.getRuntime().exec("javac factorial.java");
}
catch(IOException e)
{
e.printStackTrace();
}
Hey I think this should work. Atleast for me it did work