Did you define the Main-Class:
entry in the jar's Manifest? If not, then here are some resources on the topic:
* http://docs.oracle.com/javase/tutorial/deployment/jar/appman.html
* http://stackoverflow.com/questions/9689793/cant-execute-jar-file-no-main-manifest-attribute
What OS and in what application do you double-click on the jar file? Typically each system (such as Windows Explorer) needs an association configured in order to know what you want it to do when you double-click. Perhaps that association is missing and so no program is run.
If your environment does, in fact, run java on the jar file and you have specified Main-Class in the manifest and yet no window appears in your graphical environment, then most likely your environment does not know that you intend for the program to be run in a console. You may need to adjust the associated program so that it runs java in a console or terminal program so that its stdout is visible. (Personally I normally open a terminal, on Ubuntu, and run 'java -jar' at the prompt)