Ever wondered, where JDeveloper puts its output? It actually prints it on the console. But usually this console is hidden in a Windows environment if you use the pre-installed link.
However it’s quite easy to enable. The pre-installed link points to
YOUR_MIDDLEWARE_HOME\jdeveloper\jdeveloper.exe. Just change it (or create another link) to point to
YOUR_MIDDLEWARE_HOME\jdeveloper\jdev\bin\jdev.exe – et voilà – you will now see a console window where JDeveloper puts its (sometimes helpful) output.