No, it's perfectly safe. The more you drink, the more you'll need to piss, so it can't easily reach toxic levels. You'll need to take consecutive shots of condense coffee for the milder symptoms to appear, and a logical person wouldn't move on past that. Alcohol reaches critical levels much faster, although there are more people who enjoy having their livers destroyed. Moderation is always key, but we don't need to worry for problems that aren't even there.
For the record.
Caffeine is a D1 stimulant. Acts quickly, lasts quite some time. Perfect in small doses for studying
Apples include various D1 and α1β1 stimulants, however there's a catch. You need to digest those to act. So an apple is good to get your day started, just not as good as when you need to get down to studying right away.
Water, doesn't have a stimulatory effect. You can always hydrate your face and easen up your pores from the swelling caffeine does to the corner of the eyes sometimes, so there's that. Hydration helps make you awake, but only if your mind has completed its REM cycles. Otherwise, it just makes you have nice skin.