I had troubles with Jar files on windows… The double click didn’t works.
This is the solution for those that has the same problem.

Type the tip on MS-DOS…

assoc .jar
.jar=jarfile

If not found then create it with ASSOC.

assoc .jar=jarfile

Now take a look in the association with the FTYPE.

ftype jarfile
jarfile=”C:\Java\jre1.6.0_10\bin\javaw.exe” -jar “%1” %*

If not found or the wrong JRE is used, use the FTYPE.

ftype jarfile=jarfile=”C:\Java\jre1.6.0_10\bin\javaw.exe” -jar “%1” %*

Worked here… lol­čśÇ