So my cat just walked over my keyboard and stuff that looks like code appeared on the screen. Is my project still secure?
It's as secure as it was before the cat edited it. Nothing has changed.
I had the same thing happen, except it was a guinea pig. I posted a question on SO about it and everyone agreed.
What language was it? As per the other answer on this issue your project seems to be completely okay but you might want to delete the code, save and recompile just to make sure.
As a preventative measure regarding future incidents like this, I suggest you stealthily trick your cat into thinking there are better places to hang out on instead of your keyboard though my lack of degree in Feline Psychology suggests that that might be futile :(
@ekavroch Because the code is written by cat, I think it is LOLCODE

My snake went accross the keyboard. It resulted in python being added.
And I spilled my coffee over my keyboard. Guess what happened. Nothing! Since Java is too verbose for nocode.
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My snake went accross the keyboard. It resulted in python being added.