Cara 1:
Right Click -> Properties -> Change -> C:\Program Files\Java\jre7\bin\javaw.exe
Cara 2 :
For Windows 7:
Start "Control Panel"
Click "Default Programs"
Click "Associate a file type or protocol with a specific program"
Double click .jar
Browse C:\Program Files\Java\jre7\bin\javaw.exe
Click the button Open
Click the button OK
Cara 3 :
Open command prompt as admin
Move to the file folder using cd command
Type java.exe -jar *filename*.jar
Press enter