Tic Tac Toe in Java - Computer wins but the message is not displayed and the program keeps running - list

Question

I have wrote a tic tac toe program. However, when the computer won, the message is not displayed and the program keeps running. But after copy the sample answer, it works.
The problem is: I couldn't figure out what's the problem with my code since it was not much difference with the sample answer.
Is it the problem of my static char [][] board?
My code:
import java.util.Arrays;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Scanner;
public class TicTacToe {
static char[][] board = {{' ', '|', ' ', '|', ' '},
{'-', '+', '-', '+', '-'},
{' ', '|', ' ', '|', ' '},
{'-', '+', '-', '+', '-'},
{' ', '|', ' ', '|', ' '}};
static ArrayList<Integer> plyPositions = new ArrayList<Integer>();
static ArrayList<Integer> cpuPositions = new ArrayList<Integer>();
public static void main(String[] args) {
printBoard();
while (true) {
//player
Scanner sc = new Scanner(System.in);
System.out.print("Enter your placement [1-9]: ");
int ppos = sc.nextInt();
while (plyPositions.contains(ppos) || cpuPositions.contains(ppos)) {
System.out.println("Positions taken! Enter a correct position.");
ppos = sc.nextInt();
}
move(ppos, "player");
plyPositions.add(ppos);
String result = checkWin();
if (result.length() > 0) {
System.out.println(result);
break;
}
//computer
Random r = new Random();
int cpos = r.nextInt(9) + 1;
while (plyPositions.contains(cpos) || cpuPositions.contains(cpos)) {
cpos = r.nextInt(9) + 1;
}
System.out.println("Computer's placement: " + cpos);
move(cpos, "cpu");
cpuPositions.add(cpos);
if (result.length() > 0) {
System.out.println(result);
break;
}
}
}
public static String checkWin() {
List topRow = Arrays.asList(1, 2, 3);
List midRow = Arrays.asList(4, 5, 6);
List botRow = Arrays.asList(7, 8, 9);
List leftCol = Arrays.asList(1, 4, 7);
List midCol = Arrays.asList(2, 5, 8);
List rightCol = Arrays.asList(3, 6, 9);
List cross1 = Arrays.asList(1, 5, 9);
List cross2 = Arrays.asList(3, 5, 7);
List<List> winning = new ArrayList<>();
winning.add(topRow);
winning.add(midRow);
winning.add(botRow);
winning.add(leftCol);
winning.add(midCol);
winning.add(rightCol);
winning.add(cross1);
winning.add(cross2);
for (List l : winning) {
if (plyPositions.containsAll(l)) {
return "Congratulations! You win :D";
}
}
for (List l : winning) {
if (cpuPositions.containsAll(l)) {
return "Oops... computer won :(";
}
}
if (plyPositions.size() + cpuPositions.size() == 9) {
return "Fair";
}
return "";
}
public static void move(int pos, String user) {
char symbol = ' ';
if (user.equals("player")) {
symbol = 'O';
} else if (user.equals("cpu")) {
symbol = 'X';
}
switch (pos) {
case 1:
board[0][0] = symbol;
printBoard();
break;
case 2:
board[0][2] = symbol;
printBoard();
break;
case 3:
board[0][4] = symbol;
printBoard();
break;
case 4:
board[2][0] = symbol;
printBoard();
break;
case 5:
board[2][2] = symbol;
printBoard();
break;
case 6:
board[2][4] = symbol;
printBoard();
break;
case 7:
board[4][0] = symbol;
printBoard();
break;
case 8:
board[4][2] = symbol;
printBoard();
break;
case 9:
board[4][4] = symbol;
printBoard();
break;
default:
break;
}
}
public static void printBoard() {
for (char[] row : board) {
for (char c : row) {
System.out.print(c);
}
System.out.println();
}
}
}
Sample code (it works well):
import java.util.*;
public class TicTacToe {
static ArrayList<Integer> playerPositions = new ArrayList<Integer>();
static ArrayList<Integer> cpuPositions = new ArrayList<Integer>();
public static void main(String[] args) {
char[][] gameBoard = {
{' ', '|', ' ', '|', ' '},
{'-', '+', '-', '+', '-'},
{' ', '|', ' ', '|', ' '},
{'-', '+', '-', '+', '-'},
{' ', '|', ' ', '|', ' '}
};
printGameBoard(gameBoard);
while (true) {
Scanner scan = new Scanner(System.in);
System.out.println("Enter your placement (1-9):");
int playerPos = scan.nextInt();
while (playerPositions.contains(playerPos) || cpuPositions.contains(playerPos)) {
System.out.println("position taken! Enter a correct Position");
playerPos = scan.nextInt();
}
placePiece(gameBoard, playerPos, "player");
printGameBoard(gameBoard);
String result = checkWinner();
if (result.length() > 0) {
System.out.println(result);
break;
}
Random rand = new Random();
int cpuPos = rand.nextInt(9) + 1;
while (playerPositions.contains(cpuPos) || cpuPositions.contains(cpuPos)) {
cpuPos = rand.nextInt(9) + 1;
}
placePiece(gameBoard, cpuPos, "cpu");
printGameBoard(gameBoard);
result = checkWinner();
if (result.length() > 0) {
System.out.println(result);
break;
}
}
}
public static void printGameBoard(char[][] gameBoard) {
for (char[] row : gameBoard) {
for (char c : row) {
System.out.print(c);
}
System.out.println();
}
}
public static void placePiece(char[][] gameBoard, int pos, String user) {
char symbol = ' ';
if (user.equals("player")) {
symbol = 'X';
playerPositions.add(pos);
} else if (user.equals("cpu")) {
symbol = 'O';
cpuPositions.add(pos);
}
switch (pos) {
case 1:
gameBoard[0][0] = symbol;
break;
case 2:
gameBoard[0][2] = symbol;
break;
case 3:
gameBoard[0][4] = symbol;
break;
case 4:
gameBoard[2][0] = symbol;
break;
case 5:
gameBoard[2][2] = symbol;
break;
case 6:
gameBoard[2][4] = symbol;
break;
case 7:
gameBoard[4][0] = symbol;
break;
case 8:
gameBoard[4][2] = symbol;
break;
case 9:
gameBoard[4][4] = symbol;
break;
default:
break;
}
}
public static String checkWinner() {
List topRow = Arrays.asList(1, 2, 3);
List midRow = Arrays.asList(4, 5, 6);
List botRow = Arrays.asList(7, 8, 9);
List leftCol = Arrays.asList(1, 2, 7);
List midCol = Arrays.asList(2, 5, 8);
List rightCol = Arrays.asList(3, 6, 9);
List cross1 = Arrays.asList(1, 5, 9);
List cross2 = Arrays.asList(3, 5, 7);
List<List> winConditions = new ArrayList<List>();
winConditions.add(topRow);
winConditions.add(midRow);
winConditions.add(botRow);
winConditions.add(leftCol);
winConditions.add(midCol);
winConditions.add(rightCol);
winConditions.add(cross1);
winConditions.add(cross2);
for (List l : winConditions) {
if (playerPositions.containsAll(l)) {
return "Congratulations you won!";
}
}
for (List l : winConditions) {
if (cpuPositions.containsAll(l)) {
return "CPU wins! Sorry :-(";
}
}
if (playerPositions.size() + cpuPositions.size() == 9) {
return "CAT";
}
return "";
}
}