Alright. So recently I downloaded a program called usb overdrive (yes that means I'm on a mac). Anyway, this program allows me to map keys on my mouse for certain apps. HOWEVER in order to select the app, I need the app(or java) file handy for selection. This is where my problem occurs. Upon starting the minecraftlauncher.app and selecting play, it launches minecraft in a new app. Where can i find this app/java file? Is there even such a file?
On mac, you're on your own. For windows, I know java is located in the program files folder, and the executable minecraft runs is javaw, so form my guess search around wherever your program files are and look for a file or app called javaw.
Technically, the minecraft launcher executes java, not minecraft. It gives java many arguments to tell java to run the minecraft.jar, how much memory to allocate, permGen space, window size, exc. But it also has multiple steps due to the fact that it first has to reach mojang's authentication servers to fetch one of the arguments. So in short, no. You cannot simply "run minecraft" with the push of a button.
One solution is to have your mouse start the launcher, and then click play manually. Another option is to have minecraft always running in a separate desktop and use things like hot corners (with mission control) to switch to it. Plus, that would mean that you don't need to wait for minecraft to load each time.