how to set input as public constanta

Question

hi all i have code main and tictactoe class

here my example of main class. in this code i input something like string number

public static void main(String[] args) {
         SwingUtilities.invokeLater(new Runnable() {
             public void run() {
                 Scanner scanner = new Scanner(System.in);
                 System.out.println("Enter number of ROW Column Do you want to use");
                 String input = scanner.next();
                 Integer Input = Integer.parseInt(input);
                new TTTGraphics2P(Input); // Let the constructor do the job
             }
          });

and this is for my class of tictactoe program. if i run this code i only have 3x3 tictactoe program, so i want to modify one of code using my input so my tictactoe will be Input x input

public class TTTGraphics2P extends JFrame {
   // Named-constants for the game board
   public static final int ROWS = 3;  // ROWS by COLS cells
   public static final int COLS = 3;
 
   // Named-constants of the various dimensions used for graphics drawing
   public static final int CELL_SIZE = 100; // cell width and height (square)
   public static final int CANVAS_WIDTH = CELL_SIZE * COLS;  // the drawing canvas
   public static final int CANVAS_HEIGHT = CELL_SIZE * ROWS;
   public static final int GRID_WIDTH = 8;                   // Grid-line's width
   public static final int GRID_WIDHT_HALF = GRID_WIDTH / 2; // Grid-line's half-width
   // Symbols (cross/nought) are displayed inside a cell, with padding from border
   public static final int CELL_PADDING = CELL_SIZE / 6;
   public static final int SYMBOL_SIZE = CELL_SIZE - CELL_PADDING * 2; // width/height
   public static final int SYMBOL_STROKE_WIDTH = 8; // pen's stroke width
 
   // Use an enumeration (inner class) to represent the various states of the game
   public enum GameState {
      PLAYING, DRAW, CROSS_WON, NOUGHT_WON
   }
   private GameState currentState;  // the current game state
 
   // Use an enumeration (inner class) to represent the seeds and cell contents
   public enum Seed {
      EMPTY, CROSS, NOUGHT
   }
   private Seed currentPlayer;  // the current player
 
   private Seed[][] board   ; // Game board of ROWS-by-COLS cells
   private JPanel canvas; // Drawing canvas (JPanel) for the game board
   private JLabel statusBar;  // Status Bar
 
   /** Constructor to setup the game and the GUI components 
 * @param input */
   public TTTGraphics2P(Integer input) {
      canvas = new DrawCanvas();  // Construct a drawing canvas (a JPanel)
      canvas.setPreferredSize(new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT));
 
      // The canvas (JPanel) fires a MouseEvent upon mouse-click
      canvas.addMouseListener(new MouseAdapter() {
         @Override
         public void mouseClicked(MouseEvent e) {  // mouse-clicked handler
            int mouseX = e.getX();
            int mouseY = e.getY();
            // Get the row and column clicked
            int rowSelected = mouseY / CELL_SIZE;
            int colSelected = mouseX / CELL_SIZE;
 
            if (currentState == GameState.PLAYING) {
               if (rowSelected >= 0 && rowSelected < ROWS && colSelected >= 0
                     && colSelected < COLS && board[rowSelected][colSelected] == Seed.EMPTY) {
                  board[rowSelected][colSelected] = currentPlayer; // Make a move
                  updateGame(currentPlayer, rowSelected, colSelected); // update state
                  // Switch player
                  currentPlayer = (currentPlayer == Seed.CROSS) ? Seed.NOUGHT : Seed.CROSS;
               }
            } else {       // game over
               initGame(); // restart the game
            }
            // Refresh the drawing canvas
            repaint();  // Call-back paintComponent().
         }
      });

my question is i want to change this field

public static final int ROWS = 3;  // ROWS by COLS cells
       public static final int COLS = 3;

become

public static final int ROWS = Input; // ROWS by COLS cells public static final int COLS = Input;

how to build it ?

thank you all

Answer 1

If you assign same value to final variable you can't change it. And it should be a non-static. If we static a final variable we can't assign a value in constructor. And don't forget to declare final variable without value. Declare final variables without value.

public final int ROWS;
 public final int COLS;

Refer this sample program to find a solution for your problem.

public class Solution {

    public final int ROWS;
    public final int COLS;

    public Solution(int input) {
        ROWS=input;
        COLS=input;
        System.out.println(ROWS);
    }

    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        int input=scanner.nextInt();
        Solution s=new Solution(input);
    }
} 

Answer 2

Just use constructor to set rows and cols:

public void run() {
    Scanner scanner = new Scanner(System.in);
    System.out.print("Total rows: ");
    int rows = scanner.nextInt();
    System.out.print("Total columns: ");
    int cols = scanner.nextInt();
    new TTTGraphics2P(rows, cols);
}

public class TTTGraphics2P extends JFrame {
    private final int rows;
    private final int cols;
    
    public TTTGraphics2P(int rows, int cols) {
        this.rows = rows;
        this.cols = cols;
    }
}

Answer 3

As you have declared the ROWS and COLS variables as static they will be initialized when class is loaded. Since they are final, once set the value cannot be changed.

To achieve your requirement you can modify the TTTGraphics2P class as below to read the input and set to the variables at class loading.

public class TTTGraphics2P extends JFrame {
    // Named-constants for the game board
    public static final int ROWS = getInput();  // ROWS by COLS cells
    public static final int COLS = getInput();
    ...
    // Read standard input from the user
    public static int getInput() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter number of ROW Column Do you want to use");
        String input = scanner.next();
        return Integer.parseInt(input);
    }
    ...
}