package bingo.shared;import java.util.Random;import java.util.Vector;import java.util.Stack;import java.io.Serializable;import java.security.*;// a Bingo card, created by the GameKeeper and signedpublic class Card implements Serializable {    public static final int SIZE = 5;    public static char[] columnTitles = { 'B', 'I', 'N', 'G', 'O' };    public BingoBall[][] boardValues = new BingoBall[SIZE][SIZE];    private byte[] signature;    public Card() {	this(new Random(System.currentTimeMillis()));    }    public Card(Random generator) {	int min=0, max=0;	for (int i = 0; i < SIZE; i ++) {            int numBalls = BingoBall.RANGE;            Vector balls = new Vector(numBalls);	    Stack randomBalls = new Stack();	    switch (i) {	    case 0:		min = BingoBall.MIN;		max = BingoBall.MAX_B;		break;	    case 1:		min = max + 1;		max = BingoBall.MAX_I;		break;	    case 2:		min = max + 1;		max = BingoBall.MAX_N;		break;	    case 3:		min = max + 1;		max = BingoBall.MAX_G;		break;	    case 4:		min = max + 1;		max = BingoBall.MAX_O;		break;	    }                // generate all 15 balls in this range            for (int j = min; j <= max; j++) {                balls.addElement(new BingoBall(j));	    }                // randomize the 15 balls            for (int k = BingoBall.RANGE - 1; k >= 0; k--) {                int num = (int)(generator.nextDouble() * (k+1));                randomBalls.push(balls.elementAt(num));                balls.removeElementAt(num);            }		 // choose 5 of them to put on the card	    for (int j = 0; j < SIZE; j ++) {		boardValues[j][i] = (BingoBall)randomBalls.pop();	    }	}	boardValues[2][2] = new BingoBall(BingoBall.FREE_SPACE);    }    public void setSignature(byte[] sig) {	signature = sig;    }    public byte[] getSignature() {	return signature;    }}