New to Java

I'm getting this errory, java.lang.OutOfMemoryError: Java heap space, but have no idea why. I'm new to java and programming in general. I read some forum post concerning this error and did java -Xrunhprof APPNAME and looked at the results. Again..I pretty much have no idea what I'm looking at, I am curious why byte[] is at the top of the profile list and i don't have a byte array in the program.

code;First class:
import java.util.*;

public class TicTacToe
{
public static void main(String[] args)
{
TicTacToeMain mainpart = new TicTacToeMain();
mainpart.display();
}
}

class TicTacToeMain
{
char[] display = {'0','1','2','3','4','5','6','7','8'};
int[] movestaken = new int[9];
boolean gamestatus=true;

Scanner keyboard = new Scanner(System.in);
GameEngine game = new GameEngine();
public void display()
{
int i;
System.out.println("\t\t\t" + display[0] + "\t|\t" + display[1] + "\t|\t" + display[2]);
System.out.println("\t\t\t\t|\t\t|");
System.out.print("\t\t\t");
for (i=0;i <=30;i++)
{
System.out.print("_");
}
System.out.println("");
System.out.println("\t\t\t" + display[3] + "\t|\t" + display[4] + "\t|\t" + display[5]);
System.out.println("\t\t\t\t|\t\t|");
System.out.print("\t\t\t");
for (i=0;i <=30;i++)
{
System.out.print("_");
}
System.out.println("");
System.out.println("\t\t\t" + display[6] + "\t|\t" + display[7] + "\t|\t" + display[8]);
System.out.println("\t\t\t\t|\t\t|");
if (gamestatus==true)

game.engineMain();

else

getPlayersNames();
}



public void getPlayersNames()
{
int number=0;
String playerO="Computer";
String playerX="Computer";
System.out.println("Enter number of players: 1 or 2");
number = keyboard.nextInt();

if (number == 2)
{
System.out.println("Enter player X's name:");
System.out.println("Enter player O's name:");
game.twoPlayerGame();
}

if (number ==1)
{ System.out.println("Enter player O's name:");
game.onePlayerGame();
}
if (number != 1 && number !=2)
{
System.out.println("Number of Players must be 1 or 2");
getPlayersNames();
}
}

}

code;Second Class:
import java.util.*;
public class GameEngine
{
TicTacToeMain mainpart = new TicTacToeMain();
Scanner keyboard = new Scanner(System.in);
public void onePlayerGame()
{
String message="Test method oneplayer reached";
System.out.println(message);
System.exit(0);
}

public void twoPlayerGame()
{
String message="Test method twoplayer reached";
System.out.println(message);
System.exit(0);

}


public void endGame()
{
System.out.println("End game");
}
public void engineMain()
{

int move;
int location2;
int putInArray;
char[] players = {'x','o'};
System.out.println("Enter your move:");
move = keyboard.nextInt();
location2=move+1;
Arrays.fill(mainpart.display, move,location2, players[0]);
System.out.println(players[0]);
putInArray=move;
Arrays.fill(mainpart.movestaken,move,location2, putInArray);
System.out.println(mainpart.movestaken[move]);
mainpart.display();

}
}

profile section from java.hprof.txt
SITES BEGIN (ordered by live bytes) Mon May 1 17:25:10 2006
percent live alloc'ed stack class
rank self accum bytes objs bytes objs trace name
1 72.15% 72.15% 48279456 5882 48279456 5882 300465 byte[]
2 18.14% 90.30% 12140448 5882 12140448 5882 300470 char[]
3 1.20% 91.49% 799816 5881 799816 5881 301114 java.util.Scanner
4 0.84% 92.34% 564672 5882 564672 5882 300474 int[]
5 0.49% 92.83% 329392 5882 329392 5882 300473 java.util.regex.Matcher
6 0.42% 93.25% 282336 5882 282336 5882 300466 java.nio.HeapByteBuffer
7 0.42% 93.67% 282336 5882 282336 5882 300471 java.nio.HeapCharBuffer
8 0.42% 94.10% 282288 5881 282288 5881 301118 int[]
9 0.35% 94.45% 235320 5883 235320 5883 300461 sun.nio.cs.UTF_8$Decoder
10 0.35% 94.80% 235320 5883 235320 5883 300464 sun.nio.cs.StreamDecoder$CharsetSD
11 0.28% 95.08% 188192 5881 188192 5881 301116 TicTacToeMain
12 0.28% 95.36% 188192 5881 188192 5881 301117 char[]
13 0.21% 95.57% 141192 5883 141192 5883 300458 java.io.InputStreamReader
14 0.21% 95.78% 141168 5882 141168 5882 300469 java.util.Scanner$1
15 0.21% 95.99% 141168 5882 141168 5882 301081 java.lang.String
16 0.21% 96.20% 141168 5882 141168 5882 301083 java.lang.String
17 0.21% 96.42% 141168 5882 141168 5882 301087 java.lang.String
18 0.21% 96.63% 141168 5882 141168 5882 301092 java.lang.String
19 0.21% 96.84% 141168 5882 141168 5882 301096 java.lang.String
20 0.21% 97.05% 141168 5882 141168 5882 301100 java.lang.String
21 0.21% 97.26% 141168 5882 141168 5882 301101 char[]
22 0.21% 97.47% 141168 5882 141168 5882 301104 java.lang.String
23 0.21% 97.68% 141168 5882 141168 5882 301105 char[]
24 0.21% 97.89% 141168 5882 141168 5882 301108 java.lang.String
25 0.21% 98.10% 141168 5882 141168 5882 301109 char[]
26 0.14% 98.24% 94128 5883 94128 5883 300463 sun.nio.cs.Surrogate$Generator
27 0.14% 98.39% 94112 5882 94112 5882 300475 int[]
28 0.14% 98.53% 94112 5882 94112 5882 301082 char[]
29 0.14% 98.67% 94112 5882 94112 5882 301084 char[]
30 0.14% 98.81% 94112 5882 94112 5882 301088 char[]
31 0.14% 98.95% 94112 5882 94112 5882 301093 char[]
32 0.14% 99.09% 94112 5882 94112 5882 301097 char[]
33 0.14% 99.23% 94096 5881 94096 5881 301115 GameEngine
34 0.13% 99.36% 90288 1589 90288 1589 300000 char[]
35 0.06% 99.42% 38512 1587 38512 1587 300000 java.lang.String
36 0.04% 99.46% 25680 10 25680 10 300000 byte[]
37 0.02% 99.48% 12648 93 799952 5882 301062 java.text.DecimalFormat
38 0.01% 99.49% 8928 186 564672 11764 301050 char[]
39 0.01% 99.51% 8928 186 564672 11764 301068 char[]
40 0.01% 99.52% 8928 186 564672 11764 301070 char[]
41 0.01% 99.53% 8520 1 8520 1 300106 byte[]
42 0.01% 99.54% 7768 199 7768 199 300000 java.lang.Object[]
SITES END

thanks in advance,
James