External process waiting

Question

Hi All,
This one's got me.
I have the following requirement in my app:
- Ability to browse for, and save files to the database.
- View (and modify if required) saved files using the default external application.
- When the default external application exits, if the file has changed, resave it to the database automatically without the need for further user action.
First part's easy.
When viewing the file, I write the file (using it's stored filename and extension from when it was saved) to a temp directory under my app's installation directory.
Second part: I see three options using ProcessBuilder and process.waitFor():
1. Use the exe (eg winword.exe) directly (requires path to the exe).
2. Use "cmd.exe /c [absolute file path]" to open the file.
3. Use "rundll32 SHELL32.DLL,ShellExec_RunDLL [absolute file path]" to open the file.
All three approaches work fine, except only the first option complies with part three of the requirement, ie only using the exe directly waits for the external app to exit.
The issue with the first approach is that I need to know the absolute path to the exe, which can vary on user's machines (eg can't guarantee that winword.exe will always be in the same directory).
The other 2 (cmd.exe and rundll32) open the app in another external process and return immediately. This prevents me from being able to detect termination of the external process and resave the file, and as the process returns immediately I can't necessarily delete the file successfully.
A solution I see to the shortfall of the first approach is to have the default apps stored as preferences/config by allowing the user to browse to and select the default apps. Can't really expect computer illiterate users to know where to find winword.exe let alone know it starts Word.
I'm open to suggestions here. If I could open the file within Java (passing a byte[]) and allow the user view and / or modify it there without it ever touching the filesystem that would be awesome. However I suspect such functionality would mean a huge footprint.
I also thought about the app being able to do it's own file search to locate winword.exe on the filesystem (eg scan c:\program files etc).
Alternatively, does anyone know how to get cmd.exe or rundll32 to wait for gui apps? This is from CMD help:
"When executing an application that is a 32-bit GUI application, CMD.EXE does not wait for the application to terminate before returning to the command prompt."Any suggestions would be really appreciated.
Thanks in advance,
Paul C.

Answer 1

The below method seems to work with Word documents, although it is not very elegant and costs 2 file rename operations at worst:
          boolean locked = true;
          String fileName = "C:/test.doc";
          String newFileName = "C:/test_renamed.doc";
          try {
               File file = new File(fileName);
               File newFile = new File(newFileName);
               boolean renamed = file.renameTo(newFile);
               System.out.println(file.getName()+" renamed to "+newFile.getName()+" = "+renamed);
               if (renamed) {
                    File oldFile = new File(fileName);
                    renamed = newFile.renameTo(oldFile);
                    System.out.println(newFile.getName()+" renamed to "+oldFile.getName()+" = "+renamed);
                    if (renamed) locked = false;
          catch(Exception e){
               e.printStackTrace();
          finally {
               System.out.println("FILE "+fileName+" LOCKED = "+locked);
          }