This is a java application that solves an Eight Puzzle. A description can be found here http://en.wikipedia.org/wiki/15_puzzle.
Basically, it is a 3x3 grid with 1 empty space. The correct solution is the numbers on the grid are ordered 1-8, from top left to bottom right.
1 2 3 4 5 6 7 8 X
The last square is an empty cell.