The method winner(boolean, boolean, boolean) is undefined for the Type TicTacToe?

Is there a reason why this error is occurring? I can't identify what's causing it to happen.

Java Code:

package tictac1;

import java.util.*;

public class TicTacToe{

  //Instance variables
  private char[][] board; //2D array of chars for the board
  public TicTacToe(){ //creates a board where each space holds whitespace
    board = new char[3][3];
    for (int row = 0; row < 3; row ++){
      for (int col =  0; col < 3; col++){
        board[row][col] = ' ';
      } // end of inner loop
    } // end of outer loop
  } 
 
  // Methods
 
  public boolean set(int row, int col, char c){ //sets (row, col) to c
    if (row >= 3 || row < 0) 
      return false;
    if (col >= 3 || col < 0) 
      return false; 
    if (board[row][col] != ' ')
    if ( !(c == 'X' || c == 'O'))
      return false;
    // assertion: row, col, c are valid
    board[row][col] = c;
    return true; 
  }
  /*if this returns true, the character c (X or O) is put 
   * at the board's [row][col] position.
   * this happens only if the variables row, col and c are valid, and 
   * the place where [row][col] refers to is not already
   * occupied (already assigned a value), 
   * other than the default whitespace.
   * this returns false if not true. */

         
  public char get(int row, int col){ 

    return board[row][col];
  }

  /*this is a getter method that 
   * retrieves the character assigned to (rol,col)
   * the variable row is an int from 0 to board.length.
   * the variable col is an int from 0 to board[0].length
   * this returns the character that is at the referred position*/
 
  public boolean isFull(){ 
    for (int row = 0; row < 3; row ++){
        for (int col = 0; col < 3; col ++){
                if (board[row][col] != ' '){
                        return false;
                }
        }
    }
    return true;
  }
/*this is a method that returns whether or not the board is fully occupied.
 *this returns false if any space in the board is whitespace.  otherwise it is true.
 **/
 public boolean isWinner(int row, int col){
         String Player = Character.toString(board[row][col]);    
         boolean onDiagonal = (row ==col)||(col== -1* row+ (board.length-1));
         boolean HorizontalWin = true; 
         boolean VerticalWin = true;
         boolean DiagonalWinOne = true; 
         boolean DiagonalWinTwo = true;
        for (int n = 0; n<board.length; n++){ //Checks rows and columns
                if(!Character.toString(board[row][n]).equals(Player))
                        HorizontalWin = false;
                if(!Character.toString(board[n][col]).equals(Player))
                        VerticalWin = false;            
        }
        if(onDiagonal){ //Checks only if move was on a diagonal
                //Checks the diagonals
                for(int n = 0; n < board.length; n++){
                        if(!Character.toString(board[n][n]).equals(Player))
                                DiagonalWinOne = false;
                        if(!Character.toString(board[n][-1*n+(board.length-1)]).equals(Player))
                                DiagonalWinTwo = false;
                }
        }
        else{
                DiagonalWinOne = false;
                DiagonalWinTwo = false;
        }
        boolean hasWon = (HorizontalWin || VerticalWin || DiagonalWinOne || DiagonalWinTwo);
        return hasWon;
 }

 /*This method takes the row and column coordinates of the last move made and checks to see
  * if that move caused the player to win. This method checks the row, column and diagonal
  * (if the move was made on a diagonal) that the move was played on to see if 
  * the winning condition was met there. 
   */
public boolean whoIsWinner(int row, int col, boolean hasWon){
        boolean xWon = false;
        boolean oWon = false;
        if (hasWon == true)
                if (board[row][col] == 'X')
                        xWon = true;
                if (board[row][col] == 'O')
                        oWon = true;
        if (xWon = true)
                return xWon;
        if (oWon = true);
                return oWon;
}
[B] private char winner(boolean hasWon, boolean xWon, boolean oWon){ 
            if (hasWon != false) 
              if (xWon == true)
                 return 'X';
                 if (oWon == true)
                         return 'O';
                 else 
                         return ' ';[/B]
 }
  public void play(){
    Scanner input = new Scanner(System.in);
    int row, col;
    char currPlayer = 'X';
    while(!isFull() && winner() != 'X' && winner() != 'O'){
              try{
                print();
                System.out.println("Player "+currPlayer+"'s Turn");
                System.out.print("Enter your move. (e.g. 1,2):");
                Scanner tokens = new Scanner(input.nextLine());
                tokens.useDelimiter(",");
                        row = tokens.nextInt();
                        col = tokens.nextInt();
                if (!set(row,col,currPlayer)){
                       throw new Exception("Error Setting.");
                }
                        }catch(Exception error){
                      if(error instanceof InputMismatchException){
                        input.nextLine();
                      }else{
                  System.out.println("Bad input");
}
        if(currPlayer == 'X'){
          currPlayer = 'O';
        }
        else{
          currPlayer = 'X';
        }
      }
      
      if(currPlayer == 'X'){
        currPlayer = 'O';
      }
      else{
        currPlayer = 'X';
      }
    }
 
    input.close();
    print();
    if (winner() == 'X'){
      System.out.println("Player X wins!!");
    }
    else if (winner() == 'O'){
      System.out.println("Player O wins!!");
    }
    else{
      System.out.println("Everybody wins!! (Sort of)");
    }
  }
/*this method plays a full game of tic-tac-toe. The method assumes the board is empty.
   * (the variables are initialized, but no moves have been made.)
   */

  public void print(){ //this method prints the current state of the board
    int col;
    System.out.print("    col");
    System.out.print("      ");
    for (col = 0; col < 3; col++){
    }
    System.out.println();
    for (int row = 0; row < 3; row ++){
      if(row == 0){
        System.out.println("    +-+-+-+");
        System.out.println("row "+ "|" +" ");
        System.out.print("    +-+-+-+");
      }
      else {
        System.out.println("    "+"|" +" ");
        System.out.print("    +-+-+-+");
      }
      for (col =  0; col < 3; col++){
        System.out.print(board[row][col] + " ");
      } // end of inner loop
      System.out.println();
    } // end of outer loop   
  }
}