Battleships.java

import java.util.Scanner;

public class Battleships {

    /*
    *   Program:    Battleships.java
    *   Purpose:    Emulate popular board game
    *   Creator:    Chris Clarke
    *   Created:    26.03.2012
    */

    // change this to a create larger or smaller board, e.g. 5 or 7
    static final int BOARDSIZE = 6;

    // create global array
    static int [][] grid = new int[BOARDSIZE][BOARDSIZE];

    // create global variables
    static int row, column;

    public static void main(String args[]) {
        Scanner scanner = new Scanner(System.in);

        int hits = 0, misses = 0;
        int numShips = 0;

        // set all grid values to zero
        for (int r = 0; r < BOARDSIZE; r++) {
            for (int c = 0; c < BOARDSIZE; c++) {
                grid[r][c] = 0;
            }
        }

        // display board dimensions
        System.out.println("Board size = "+BOARDSIZE+" by "+BOARDSIZE);
        System.out.println("Row and column are 0 to "+(BOARDSIZE-1));

        // set the number of ships on the board
        do {
            System.out.print("Enter number of ships(1..5): ");
            numShips = scanner.nextInt();
        } while (numShips<1||numShips>5);

        // set targets, 1 for each ship
        for (int i=0; i<numShips; i++)
            setTarget();

        // keep getting user input and checking it
        do {
            // get row
            System.out.print("Enter row: ");
            row = scanner.nextInt();
            // get column
            System.out.print("Enter column: ");
            column = scanner.nextInt();

            // check valid row and column
            if ( row < 0 || row > (BOARDSIZE-1))
                System.out.println( "Error in row number");
            else if ( column < 0 || column > (BOARDSIZE-1))
                System.out.println( "Error in column number");
            else if ( grid[row][column] == 1) {
                System.out.println( "***** hit! *****");
                // will need to register as a miss if same square tried again,
                // so change value
                grid[row][column] = 2;
                hits++;
            } else {
                System.out.println( "miss!");
                misses++;
            }
        } while (hits<numShips);

        System.out.print("Game Over.  You won in ");
        int attempts = hits + misses;
        if (attempts == 1) {
            System.out.println("1 attempt.  Lucky!");
        } else {
            System.out.println(attempts+" attempts.");
        }
    }

    public static void setTarget() {
        // select a blank square at random, set its value to 1

        row = (int) (Math.random()*BOARDSIZE);      // 0 to BOARDSIZE-1 inclusive
        column = (int) (Math.random()*BOARDSIZE);   // 0 to BOARDSIZE-1 inclusive
        if (grid[row][column]==0) {         // blank square
            grid[row][column] = 1;          // set a battleship
        } else {
            setTarget();                // recursive procedure call
        }
    }
}