Runing .exe from Java

[Java_B]

Hello All,

I'm a beginner as far as Java goes, so please be kind. The only reason I'm getting acquainted with it is because I must, I'd rather stick to my few skills in C. The question here is very simple, I'm trying to run this .exe file located in a certain directory in my Windows machine. I finally managed how to tell Java to run it (took me 6 hours to figure out how to refer to a path when it has spaces between words), but now the .exe won't find any of the files I intend to manipulate (Within the windows file system). If I run the program from command prompt or even by double clicking, it works just fine. If you have suggestions feel free to modify the code, here's everything I've tried:

	  public static void Run_RK4(){
		  
		  try { 
			  System.setProperty("user.dir", "C:\\Docume~1\\AndresC\\MyDocu~1\\Norwood\\Lumped_parameter\\C_Code"); //Failed attempt to set current directory
			  Runtime rt=Runtime.getRuntime();
                          
                          //1st Try
			  //String rk4path="cmd.exe /C start C:\\Docume~1\\AndresC\\MyDocu~1\\Norwood\\Lumped_parameter\\C_Code\\Norwood_Main_Read-Write.exe";
			  //2nd Try
                          //String[] rk4path = {"cmd.exe", "/C", "start", "C:\\Docume~1\\AndresC\\My Documents\\Norwood\\Lumped_parameter\\C_Code\\Norwood_Main_Read-Write.exe"};
			  //3rd Try
                          //String[] rk4path = new String[4];
			  //rk4path[0] = "cmd.exe";
			  //rk4path[1] = "/C";
			  //rk4path[2] = "start";
			  //rk4path[3] = "C:\\Docume~1\\AndresC\\MyDocu~1\\Norwood\\Lumped_parameter\\C_Code\\Norwood_Main_Read-Write.exe";
			  
		          rt.exec(rk4path);

			  //(B) Calling an .exe from java 
			  //rt.exec("C:\\WINDOWS\\NOTEPAD.exe");
			  //rt.exec("C:\\Docume~1\\AndresC\\MyDocu~1\\Norwood\\Lumped_parameter\\C_Code\\Norwood_Main_Read-Write.exe");
		      } 
			  catch(Throwable t) 
			  { 
			  System.out.print(t.getMessage()); 
			  }
               }

[Junky]

Google pitfalls of runtime exec to learn more about the numerous known issues.

[doWhile]

Try running your java application from the same directory as the your exec application, passing the exec name rather than the full path.

[Java_B]

Even if I figure out how to use the GoodWindowsExec.java in the reference there's no guarantee my *.exe is not going to behave the same way, from what I can see.
As far as changing the directory, not an option since the Java code is actually a macro that I use to control a commercial Computational Fluid Dynamics software. What goes on internally is beyond me. I can't believe doing such a SIMPLE, EVERY DAY task is that counter intuitive, even the more arcaic C language works just fine.

[doWhile]

Even if I figure out how to use the GoodWindowsExec.java in the reference there's no guarantee my *.exe is not going to behave the same way, from what I can see.
As far as changing the directory, not an option since the Java code is actually a macro that I use to control a commercial Computational Fluid Dynamics software. What goes on internally is beyond me. I can't believe doing such a SIMPLE, EVERY DAY task is that counter intuitive, even the more arcaic C language works just fine.

I don't really understand the argument about moving the java code, but be that as it may the problem here is that the exe you are running looks for and/or writes files relative to its launch directory...that launch directory is that of the java application. Move the java application, problem solved.

That being said, a better alternative that I just discovered would to see if using a ProcessBuilder solve the problem.
ProcessBuilder (Java Platform SE 6)
Sets its directory to that of the application, then call the application directly (rather than using the full path)

ProcessBuilder pb = new ProcessBuilder("yourappname");
pb.setDirectory(new File("my app directory"));
Process p = pb.start();

[Java_B]

doWhile,

Thanks for the advice. I'm using the latest Eclipse to compile. Your second line pb.setDirectory is not defined for the type Process Builder. Here's what I have

			  ProcessBuilder pb = new ProcessBuilder("Norwood_Main_Read-Write.exe");
			  pb.setdirectory(new File("C:\\Documents and Settings\\AndresC\\My Documents\\Norwood\\Lumped_parameter\\C_Code"));
			  Process p = pb.start();

I tried deleting the set, which will allow the program to run, but doesn't run the .exe file. Please pardon if I'm missing something obvious here, I'm a complete noob.

Thanks

[Junky]

Did you try reading the API to see what methods the class does have?

[Java_B]

Looked at the whole thing Java Platform SE 6 couldn't find anything relating the instruction set with directory.
My own ignorance aggravates me, but seriously guys, this issue should have a simple solution. Is this really that uncommon? How about the equivalent of chdir, how hard is that in Java.

[doWhile]

setdirectory != setDirectory

This does a similar thing to the System.setProperty method call you make in your first code snippet (which I seemed to have overlooked on my first look at your code). After setting the correct directory make the application call by name not by full application path.