Minesweeper revisions, generate a minesweeper board of any size, and number of mines

MinesweepField.java

/*
     Challenge #108
     http://www.reddit.com/r/dailyprogrammer/comments/126905/10272012_challenge_108_intermediate_minesweeper/
     Daniel Mills
     
     Create a 15x15, 20 Mine Minesweeper Field
     Revision: updated to be able to increase boardsize and mines
 */

import java.util.Random;

public class MinesweepField {

	private class BoardPoint {
		int x;
		int y;
		public BoardPoint(int x,int y) {
			this.x = x;
			this.y = y;
		}
	}
	
	static Random rdm = new Random();
	private int SIZE = 20;
	private final char MINE = 'M';
	private final int MINE_COUNT = 20;
	
	private BoardPoint[] minelocations = new BoardPoint[MINE_COUNT];
	private BoardPoint[] checkLocations;
	private char[][] field;
	private int[][] values;
	
	public void printField() {
		for(int i=0; i < SIZE;i++) {
			for(int j =0; j < SIZE;j++) {
				System.out.print("| "+field[i][j] + " ");
			}
			System.out.print("|");
			//make and print divider line
			String line = "\n";
			for(int x =0; x < SIZE*4;x++)
				line +="-";
			System.out.println(line);
		}
	}
	
	public void calculateNonMineValues() {
		//for each mine
		for(int i =0; i < minelocations.length;i++) {
			//for each check spot around mine
			for(int j=0; j < checkLocations.length;j++) {
				
				BoardPoint temp = new BoardPoint(minelocations[i].x+checkLocations[j].x, minelocations[i].y+checkLocations[j].y);
					//if checkLocation inside board
					if( (temp.x > -1 && temp.x < SIZE) && (temp.y > -1 && temp.y < SIZE ))  {
						//if not another mine at location
						if(field[temp.x][temp.y] != MINE) {
							//increase value at location
							values[temp.x][temp.y]++;
						}
					}			
			}
		}	
	}

	public void addValuesToBoard() {
		//check each spot on board
		for(int i=0;i < SIZE;i++) {
			for(int j=0;j< SIZE;j++) {
				//if location not a mine or has no value
				if(field[i][j] != MINE && values[i][j] != 0) {
					//put value in string and put on display field
					String x = ""+values[i][j]; 
					field[i][j] = x.charAt(0);
				}
			}
		}
	}
	
	public MinesweepField() {
		
		//check locations are the 9 spots around a mine to check values
		checkLocations = new BoardPoint[9];
		checkLocations[0] = new BoardPoint(-1,-1);checkLocations[1] = new BoardPoint(-1,0);checkLocations[2] = new BoardPoint(-1,1);
		checkLocations[3] = new BoardPoint(0,-1);checkLocations[4] = new BoardPoint(0,0);checkLocations[5] = new BoardPoint(0,1);
		checkLocations[6] = new BoardPoint(1,-1);checkLocations[7] = new BoardPoint(1,0);checkLocations[8] = new BoardPoint(1,1);
		
		//create field empty field
		field = new char[SIZE][SIZE];
		for(int i =0; i < SIZE;i++)
			for(int j=0;j< SIZE;j++)
				field[i][j] = ' ';
		
		//create values field and set all values to 0
		values = new int[SIZE][SIZE];
		for(int i =0; i < SIZE;i++)for(int j =0;j< SIZE;j++) values[i][j]=0;
		
		//set number of mines and place on field
		int mines = MINE_COUNT;
		while(mines > 0) {
			int rx = rdm.nextInt(SIZE);
			int ry = rdm.nextInt(SIZE);
			
			//if rx,ry == free space place mine
			if(field[rx][ry] == ' ') {
				field[rx][ry] = MINE;
				//store mine location
				minelocations[mines-1] = new BoardPoint(rx,ry);
				mines--;
			}
		}		
		//set values around mines
		calculateNonMineValues();
		//add numbers to board
		addValuesToBoard();		
	}
	
	public static void main(String[] args) {
		MinesweepField ms = new MinesweepField();
		ms.printField();	
	}	
}