An example of a command-line game of Tic Tac Toe written in Java.
The point is to exhibit the best practice of using single-purpose modular methods for each task of the program, keep the main method simple and focused on the core logic, use javadoc comments to describe the class as a whole and each individual method, and to show how two-dimensional arrays can be used to manipulate row/column type data.
Two methods are left intentionally undone, for you to complete: isWin and isBoardFull.