Landlord Right of Entry, NJ

I am a tenant in a 2-apartment converted duplex in New Jersey. My landlord is slow to fix problems in the apt. and when he does, he shows up unannounced. After mentioning a privacy issue, he then emailed me and said he may be by sometime in the next week. That wednesday, I recieved a call from my landlord, letting me know he was in the apt. Is this considered reasonable notice? While it was in advance, it was vague. If this is legal, what is stopping the landlord from saying I will be over sometime during the life of the lease. In addition, does the notice have to be written? Does email count? - Is this your question? Add additional information