Board.java

import java.util.Random;

/**
 * This class generates the tank array
 * and displays the board state.
 */
public final class Board {

    public static Tank[][] tanksMatrix = new Tank[2][2];
    public static int bulletsFiredCounter = 0;
    public static final int MAX_AMOUNT_OF_TANKS = new Random().nextInt(4) + 1;

    /**
     * Returns a reference to a tank from its position.
     * 
     * @param position A number from 1 to 4
     * @return A reference to an element of the tanks array
     */
    public static Tank getTankFromPosition(int position) {
        if (position == 1)
            return tanksMatrix[0][0];
        else if (position == 2)
            return tanksMatrix[0][1];
        else if (position == 3)
            return tanksMatrix[1][0];
        else
            return tanksMatrix[1][1];
    }

    /**
     * Generates 1 to 4 tanks (randomly chosen number)
     * and stores them in the tanks array.
     */
    public static void generateTanks() {
        int tanksCreatedCounter = 0;

        // Traverse 2D array/matrix
        for (int i = 0; i < tanksMatrix.length; i++) {
            for (int j = 0; j < tanksMatrix[i].length; j++) {
                // Initialize tank only if counter below limit
                if (tanksCreatedCounter < MAX_AMOUNT_OF_TANKS) {
                    if (new Random().nextBoolean() == true) {
                        tanksMatrix[i][j] = new PanzerTank();
                    } else {
                        tanksMatrix[i][j] = new AlienTank();
                    }
                    tanksCreatedCounter++;
                } else {
                    // Position left null
                    continue;
                }
            }
        }
    }

    /**
     * Prints the board state,
     * displaying, for each tank,
     * type and health
     */
    public static void displayBoardState() {
        System.out.println("-----------------");
        System.out.println(("| " + tanksMatrix[0][0] + " | " + tanksMatrix[0][1] + " |")
                .replace("null", "     "));
        System.out.println("-----------------");
        System.out.println(("| " + tanksMatrix[1][0] + " | " + tanksMatrix[1][1] + " |")
                .replace("null", "     "));
        System.out.println("-----------------");
        System.out.println();
    }

    /**
     * Prints the board state but
     * numbered from 1 to 4 for
     * nicer prompting on the user.
     * 
     * @see displayBoardState()
     */
    public static void displayNumberedBoardState() {
        System.out.println();
        System.out.println("-----------------");
        System.out.println(("| " + tanksMatrix[0][0] + " | " + tanksMatrix[0][1] + " |")
                .replace("null", "     "));
        System.out.println("|   1   |   2   |");
        System.out.println("-----------------");
        System.out.println(("| " + tanksMatrix[1][0] + " | " + tanksMatrix[1][1] + " |")
                .replace("null", "     "));
        System.out.println("|   3   |   4   |");
        System.out.println("-----------------");
        System.out.println();
    }

}