This is a jar launcher in the form of a shell script
java -jar app.jar
To make it executable by owner,group and readable by world:
chmod 754 launchjar
whoiam does not exist. Closest thing is whoami, but it is not a privilege, it is a command to print the effective user id. Please clarify. If you want to run it from the application menu, install alacarte
su - -c "yum install alacarte"
then log out and back in, right-click on Applications->Edit Menus, select the menu you want to contain the new entry on the left and then click on the New Item button in the top right corner. Leave Type: Application if it's a GUI or else change the Type to "Application in Terminal", enter Name, Command (the complete path to launchjar, or click on Browse to select it from the file picker) and Comment. By clicking on the icon (top left), you can change the icon for the new command too. Then click Ok, Close and you 're done