JButton子级不更新文本

Question

I'm building a game where the object is to move a knight around a world and be able to fight other knights.

I've got a class Main that starts the game:

public class Main {

    public static void main(String[] args) {    
    new Game();
    }
}

A class Game that creates a JFrame:

import java.awt.GridLayout;

import javax.swing.JFrame;

public class Game {

    public Game() {
        JFrame frame = new JFrame();
        frame.setTitle("Knights Tournament");
        frame.add(new Board());
        frame.setSize(700, 700);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

And a class Board which (you guessed it!) creates the GameBoard:

public class Board extends JPanel {

    Tile[][] grid = new Tile[15][15];

    public Board(){

        // Create the grid
        CreateGrid();

        // Add the player
        grid[0][0] = new Player(0, 0);
    }

    // Method that creates a grid of tiles
    private void CreateGrid() {
        setLayout(new GridLayout (15, 15));
        for(int i = 0; i < 15; i++){
            for(int j = 0; j < 15; j++){
                grid[i][j] = new Tile(i, j);
                add(grid[i][j]);
            }
        }
   }
}

The grid initialy consists of 15x15 tiles.

 public class Tile extends JButton implements ActionListener {

    public int xCo;
    public int yCo;

    public Tile(int x, int y) {
        setXCo(x);
        setYCo(y);
    }

    public void setXCo(int x) {
        this.xCo = x;
    }

    public void setYCo(int y) {
        this.yCo = y;
    }

    public int getXCo() {
        return xCo;
    }

    public int getYCo() {
        return yCo;
    }
}

The problem i'm facing is the following: I would like to replace grid[0][0] by another class Player that expands tile. The difference between tile and player would be that the Jbutton gets a text saying 'P' i've tried this:

public class Player extends Tile{

    public Player(int x, int y) {
        super(x, y);
        this.setText("P");
   }

}

In the constructor of the class board i tried changing grid[0][0] from tile to player so it would display P, but it doesn't do so for some reason (It does change the type of grid[0][0] to player...) I hope someone can help.

Answer 1

You shouldn't try and maintain the state of the object with the UI, per se . Rather the UI should visualise the state of the underlying logic of the game (or model). This allows you to modify the model, change the rules, add/remove elements (think adding new monsters or loot for example), without need to physically modify the UI or how it visualise this state (to a large degree).

The idea is, the Player attributes should be maintain with an class of it's own, which is managed by the model. The UI would then be used to visualise the state the model.

When clicked the Tile would notify the "controller". The controller would request stateful information from the games "model" and based on this information the "controller" would change the state of the button(s) to meet the requirements of the "model"

This would simply require the "controller" to update the button(s) information (text/icons) without needing to change the physical buttons.

This separates the responsibilities into defined layers and reduces the coupling of the code, so one or more layers can change, but the overall structure doesn't break down or need to be heavily modified to handle these changes.

The model is responsible for maintaining the virtual state of the game, for managing the interactions between the individual game objects (combat etc).

The UI is responsible for providing a visualisation of the model for the user and the controller is used to manage the interaction between the take, taking user input and pass it to the model, monitoring changes to the model's state and telling the UI when it needs to update.

The Model–view–controller paradigm is a common approach used in GUI development across different lanuguages. Take a look at Model–view–controller for more details.