Lets start by creating our AppleScript to launch an executable jar file.
Open up Applescript Editor and add the do shell script command:
Run it to make sure it works.
Save this script in a good place. Maybe the folder where you script/app is.
From the AppleScript editor, you will need to select File → Export.
Give your application a name and specify "Application" for File Format and click Save.
You now have a application that can be dragged into your Applications Folder to execute your script.
Find a new icon image to add to your App. We will need to load it into the Cut/Past buffer. If it is an icon from google search, perform the following:
Open Finder and find your newly created Application. Right mouse click the Application and select "Get Info".
From the Get Info screen we will past a new icon to it. Click the icon at the top of the Get Info screen and hit CMD-V. Your icon should now be changed.
Close this window and you are all done.