I got it! Here's the solution:
First, you can use Eclipse to create a jar file if you're like me and prone to making noob mistakes. Here's how... in Eclipse, right-click the package, Export, JAR file, next, type in destination folder, next, next, Browse for Main Class, Finish. You can test your jar file to make sure it's functional by opening a terminal and typing:
Once you have a functional jar file, go to your home folder and create a new empty file called "runit" or something, with no extension. Open it and enter the following:
java -jar "/<full path>/<filename>.jar"
Make sure to include the quotation marks, and then save it. Now make it an executable bash file by opening a terminal and typing:
You can test your bash file to make sure it's functional by opening a terminal and typing:
Now create a new launcher by right-clicking on the desktop & selecting "Create Launcher." Enter a name, check the box that says "run in terminal", and enter the following next to "Command":
Pick a cool icon & hit "create" and you're done! You now have a double-click-able icon for your "Hello World" Java program!