I can post the code because i have 5 classes david and the code is very long, If you could direct me to the library that can help me i will be very grateful most of the code is complete already i have pac man colliding with the food class n=and have drawn up the maze and incorporated the pacman the theme song. 

You might try a path finding algorithm e.g. A* or Dijkstra - there is a library that does this but it won't be easy to incorporate into an existing sketch.

Can see a demo of it in action here

I am not sure if there is a processing library for that specific subject, there are lots of pages on the web about the pacman ghosts AI, for example http://gameinternals.com/post/2072558330/understanding-pac-man-ghost-behavior