 Now that we've learned about object-oriented programming, or at least we started to get a feel for all those subtle nuances like inheritance and having multiple classes inside of a single file, polymorphism. What we actually get into now is the fact that we're going to take all those things that we've been working on and sort of pie them together. How we get there is with graphic user interfaces, also known as, well, in our case, Java FX. Now, I said graphic user interface. That's also normally referred to as a GUI, G-U-I. And it's just the acronym for that. The idea behind it is everything that we've been working on so far, it's been the opposite. It's been what we call command line programs. And they're not bad, but we have to think about our end user. And our end user is scared of command line interfaces. If you're taking a programming class, you've obviously hit that level of kind of knowing the computer, but show hands. How many of you have ever had to tech support someone on the phone? It sucks. Well, guess what? Try and imagine telling your mom to do IP config slash release on the command line. It ain't going to happen. It's just they suddenly, you know, you have to go home and work on it because that's just not going to happen. The graphic user interface, the GUI allows the user to feel a little bit more comfortable. It's the same kind of concept with your car. You don't see all these different levels of bells and whistles that you have to flip and switch and everything. It's not like a rocket ship. It's just turn the key. I drive. I don't have to control, you know, the fuel intake. I mean, I can, but that's upgrading my system. Something to take note of with our GUI. Since we are just learning these things, yours are going to look like crap. Yours are going to look terrible. But the idea behind it is we are now dealing with two new words. The user interface and the user experience. Now user experience also kind of referred to as UX. That starts to get into how the person uses the product. You know, one of the major hallmarks of the Apple product was the fact that you just touched it and it worked. Same kind of thing. You just typed stuff into Google and it worked. We're not there yet. You've got a few years before you're going to start becoming a UX experienced person. But okay, well, we're starting to get with GUIs and I just want to show you this plug. Most of my lectures actually use get the GNU GNU image manipulation program. And so if you're looking into, oh, well, I want to make my own icons. I want to make my own graphics for my own program for my own GUI. Well, if you don't afford Photoshop, if you can't afford Photoshop and you're not going to pirate it, well, you know, maybe throw it to the open source community. Because obviously they kind of like that. Now, one of the things we did last week was we introduced the idea of handling two separate versions. We did sort of the robot class for our assignment and the room as well. But we also had this visualize simulation, visualize simulation. Now, here's where things became interesting. Notice how you guys actually never had to do anything in this file. You didn't I told you not to touch it. I told you not to look at it. But you designed everything inside of robot, Roomba or standard robot, random robot and rectangular room. You designed everything that had no GUI to it. There's no, you know, even our rectangle room that had nothing to it. Well, this is actually known as a term called back in. It's the back end. It's the man behind the curtain. You know, why does Microsoft work? Well, there's a bunch of stuff. Why does Microsoft Excel work? That's a better example. Why does this work inside of Microsoft Excel? Well, it just does. Okay, that's not a good answer. It's because someone already built it in the past. Now, why is this important? Again, that was the back end. This visualize simulation, Microsoft Excel, you know, what me and you see when we open it up, that's known as the front end. It's the front of a business. It's the, yeah, you think about that front of a business looks a lot better than the back of a business where you kind of throw out the garbage and you hope no one goes back there except for the people you pay to go back there and sweep glass. The front end allows me to adjust sort of how it looks. Think about Microsoft Excel 2010 versus 2013. Well, did this sum formula change at all? No. I mean, they added, don't get me wrong, they added a bunch of new components to there that I can work with from Excel to 2010 to 2013. But really, the focus was the front end changed for the average user. But this guy right here, this sum formula, it stayed the same because that's in the back end. It's already been built. We can slap a new coat of paint on it every time we need to now. And that's exactly what we saw. A few of you actually were changing the color of the robot. You know, one person changed it from red to pink. It's because you can do that. It's because that has no boundary to the actual back end work.