four-in-line/src/Game.java

import java.util.Random;

public class Game {
    private PlayField field;
    private ConsoleReader consoleReader;
    private final Random move = new Random();

    public Game(int width, int height, ConsoleReader cr) {
        field = new PlayField(width, height);
        consoleReader = cr;
    }

    public void run() {
        Player[] players = new Player[] { new Player('x', false), new Player('o', true) };
        while(true) {
            for(Player player : players) {
                if(player.hasAI()) {
                    if(doAITurn(player)) {
                        return;
                    }
                } else if(doTurn(player)) {
                    return;
                }
            }
        }
    }

    public boolean hasEnded(Player player, int x, int y) {
        if(field.hasWon(player, x, y)) {
            printWinner(player);
            return true;
        }
        if(field.isDraw()) {
            System.out.println("Draw.");
            return true;
        }
        return false;
    }

    private void printWinner(Player player) {
        System.out.println("Player " + player.getToken() + " has won.");
    }

    public boolean doTurn(Player player) {
        int width = field.getWidth();
        String s = "Where do you want to set your meeple? (1-" + width + ")";
        while(true) {
            System.out.println(s);
            int x = consoleReader.readInt(s) - 1;
            if(x < 0 || x >= width) {
                continue;
            }
            int y = field.getFreeY(x);
            if(y != -1) {
                return setAndCheck(x, y, player);
            }
        }
    }

    public boolean doAITurn(Player player) {
        System.out.println("AI's turn:");
        while(true) {
            int x = move.nextInt(field.getWidth());
            int y = field.getFreeY(x);
            if(y != -1) {
                return setAndCheck(x, y, player);
            }
        }
    }

    public boolean setAndCheck(int x, int y, Player player) {
        field.setPos(x, y, player);
        field.print();
        return hasEnded(player, x, y);
    }
}