Exercise 7.9

import java.util.Scanner;

public class Exercise7_9 {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);

    String[][] choices = { { " ", " ", " " }, { " ", " ", " " }, { " ", " ", " " } };
    String currentPlayer = "X";
    String winner = "";
    int row, column;
    while (true) {
      System.out.println("-------------");
      System.out.println("| " + choices[0][0] + " | " + choices[0][1] + " | " + choices[0][2] + " |");
      System.out.println("-------------");
      System.out.println("| " + choices[1][0] + " | " + choices[1][1] + " | " + choices[1][2] + " |");
      System.out.println("-------------");
      System.out.println("| " + choices[2][0] + " | " + choices[2][1] + " | " + choices[2][2] + " |");
      System.out.println("-------------");
      if (winner != "") {
        System.out.println(winner + " player won");
        break;
      }
      System.out.print("Enter a row (0, 1, or 2) for player " + currentPlayer + ": ");
      row = in.nextInt();
      System.out.print("Enter a column (0, 1, or 2) for player " + currentPlayer + ": ");
      column = in.nextInt();
      if ((row <= 2 && row >= 0) && (column <= 2 && column >= 0) && (choices[row][column] == " ")) {
        choices[row][column] = currentPlayer;
      } else {
        System.out.println("Enter valid place");
        continue;
      }
      winner = Exercise7_9.winnerCheck(choices, currentPlayer);
      currentPlayer = (currentPlayer == "X") ? "O" : "X";
    }
  }

  public static String winnerCheck(String[][] choices, String currentPlayer) {
    String conditions[] = new String[8];
    conditions[0] = choices[0][0] + choices[0][1] + choices[0][2];
    conditions[1] = choices[1][0] + choices[1][1] + choices[1][2];
    conditions[2] = choices[2][0] + choices[2][1] + choices[2][2];
    conditions[3] = choices[0][0] + choices[1][0] + choices[2][0];
    conditions[4] = choices[0][1] + choices[1][1] + choices[2][1];
    conditions[5] = choices[0][2] + choices[1][2] + choices[2][2];
    conditions[6] = choices[0][0] + choices[1][1] + choices[2][2];
    conditions[7] = choices[0][2] + choices[1][1] + choices[2][0];
    for (String condition : conditions) {
      if (condition.equals("XXX") || condition.equals("OOO")) {
        return currentPlayer;
      }
    }
    return "";
  }
}