is the J a club? if not, AJcc may be his most likely holding. from your actions, there is no reason for villain to believe you DON'T have an overpair, so ask yourself: "why does he want to shove here?" you have to assume that he assumes you might call with a hand like AcA.

so why does he want his money in the center? because he is either way ahead, or has a monster draw like AJcc and wants it all in the pot asap, along with fold equity. this is all assuming he isn't dominique the donkey from that ol' timey christmas song, believing AJ is the beast from the east.

In general, when i'm in these spots I just ponder three questions:

1. what does he think i have?
2. what does he think i'll do with what he thinks i have?
3. does he have the slightest idea what's going on right now?
(not necessarily in that order)