如何從另一個類訪問JButton

Question

我有兩個類'UserInterface'和'GameEngine'，我已經在UserInterface中聲明了一個JButton組件，我試圖使用其中一個變量，即使用來自'UserInterface'中變量'button1'的'horizo​​ntalWin'方法中的類“ GameEngine”。

我收到此錯誤，而是“找不到符號-變量button1”

用戶界面：

public class UserInterface implements ActionListener
{
 private GameEngine game;
 private JFrame frame;

 JButton button1 = new JButton("");
 JButton button2 = new JButton("");
 JButton button3 = new JButton("");
 JButton button4 = new JButton("");
 JButton button5 = new JButton("");
 JButton button6 = new JButton("");
 JButton button7 = new JButton("");
 JButton button8 = new JButton("");
 JButton button9 = new JButton("");

 /**
 * Create a user interface.
 * @param engine The game's engine.
 */
 public UserInterface(GameEngine engine)
 {
    game = engine;
    makeFrame();
 }

 //some methods
}

GameEngine：

public class GameEngine {
 private String buttonName;
 boolean winner = false;
 byte count;

public GameEngine()
{
    count = 0;
}

public void horizontalWin()
{
    if(button1.getText()==button2.getText() && button2.getText()==button3.getText() && button1.getText()!="" )
    {
        winner=true;
        playAgain(buttonName);

    }
    // Horizontal win row 2
    else if(button4.getText()==button5.getText() && button5.getText()==button6.getText() && button4.getText()!="" )
    {
        winner=true;
        playAgain(buttonName);

    }
    // horizontal win row 3
    else if(button7.getText()==button8.getText() && button8.getText()==button9.getText() && button7.getText()!="")
    {
        winner=true;
        playAgain(buttonName);

    }

}

Answer 1

我認為您並不是真的想要這樣做，也不希望您的游戲引擎試圖從視圖中獲取變量。 而是為什么不讓您的視圖在按下按鈕時通知引擎或“模型”（通常通過稱為“控件”的內容）。引擎便可以跟蹤所按下的內容並相應地更改其狀態。然后根據發動機狀態的變化而變化。

例如：

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.*;
import javax.swing.event.SwingPropertyChangeSupport;

public class TicTacToe  {

   private static void createAndShowGui() {
      View mainPanel = new View();

      JFrame frame = new JFrame("TicTacToe");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

@SuppressWarnings("serial")
class View extends JPanel {
   private static final int GAP = 2;
   private static final Font BTN_FONT = new Font(Font.SANS_SERIF, Font.BOLD, 42);
   private JButton[][] gameGrid = new JButton[Engine.ROWS][Engine.ROWS];
   private Engine engine = new Engine();

   public View() {
      engine.addPropertyChangeListener(Engine.GAME_OVER, new GameOverListener());

      JPanel gameGridPanel = new JPanel(new GridLayout(Engine.ROWS, Engine.ROWS, GAP, GAP));
      for (int i = 0; i < gameGrid.length; i++) {
         for (int j = 0; j < gameGrid[i].length; j++) {
            gameGrid[i][j] = createGameGridButton(i, j);
            gameGridPanel.add(gameGrid[i][j]);
         }
      }

      JButton resetBtn = new JButton(new ResetAction("Reset", KeyEvent.VK_R));
      JPanel northPanel = new JPanel();
      northPanel.add(resetBtn);

      setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
      setLayout(new BorderLayout(GAP, GAP));
      add(gameGridPanel, BorderLayout.CENTER);
      add(northPanel, BorderLayout.NORTH);
   }

   private JButton createGameGridButton(int i, int j) {
      JButton button = new JButton();
      button.setName(String.format("%d,%d", i, j));
      button.setText(XO.BLANK.getText());
      button.setFont(BTN_FONT);
      button.addActionListener(new GridButtonListener(i, j));
      return button;
   }

   private class GridButtonListener implements ActionListener {
      private int i;
      private int j;

      public GridButtonListener(int i, int j) {
         this.i = i;
         this.j = j;
      }

      @Override
      public void actionPerformed(ActionEvent e) {
         if (engine.isGameOver()) {
            return;
         }
         AbstractButton source = (AbstractButton) e.getSource();
         String text = source.getText();
         if (text.trim().isEmpty()) {
            source.setText(engine.getTurn().getText());
            engine.setXO(i, j);
         }
      }
   }

   private class ResetAction extends AbstractAction {
      public ResetAction(String text, int mnemonic) {
         super(text);
         putValue(MNEMONIC_KEY, mnemonic);
      }

      public void actionPerformed(ActionEvent e) {
         engine.reset();
         for (JButton[] row : gameGrid) {
            for (JButton button : row) {
               button.setText(XO.BLANK.getText());
            }
         }
      };
   }

   private class GameOverListener implements PropertyChangeListener {
      @Override
      public void propertyChange(PropertyChangeEvent evt) {
         if (evt.getNewValue() == Boolean.TRUE) {
            JOptionPane.showMessageDialog(View.this, engine.getTurn()
                  .getText() + " is a winner!", "We Have a Winner!",
                  JOptionPane.INFORMATION_MESSAGE);
         }
      }
   }
}

class Engine {
   public static final int ROWS = 3;
   public static final String GAME_OVER = "game over";
   private XO[][] grid = new XO[ROWS][ROWS];
   private XO turn = XO.X;
   private boolean gameOver = false;
   private SwingPropertyChangeSupport pcSupport = new SwingPropertyChangeSupport(
         this);

   public Engine() {
      reset();
   }

   public XO getTurn() {
      return turn;
   }

   public boolean isGameOver() {
      return gameOver;
   }

   public void setXO(int row, int col) {
      grid[row][col] = turn;
      checkForWin(row, col);
      turn = (turn == XO.X) ? XO.O : XO.X;
   }

   public void reset() {
      for (int r = 0; r < grid.length; r++) {
         for (int c = 0; c < grid[r].length; c++) {
            grid[r][c] = XO.BLANK;
         }
      }
      turn = XO.X;
      gameOver = false;
   }

   public void checkForWin(int i, int j) {
      boolean win = true;
      for (int col = 0; col < grid.length; col++) {
         if (grid[col][j] != turn) {
            win = false;
         }
      }
      if (!win) {
         win = true;
         for (int row = 0; row < grid[i].length; row++) {
            if (grid[i][row] != turn) {
               win = false;
            }
         }
      }
      if (!win && i == j) {
         win = true;
         for (int k = 0; k < grid.length; k++) {
            if (grid[k][k] != turn) {
               win = false;
            }
         }
      }
      if (!win && i + j == 2) {
         win = true;
         for (int k = 0; k < grid.length; k++) {
            if (grid[k][2 - k] != turn) {
               win = false;
            }
         }
      }

      if (win) {
         setGameOver(true);
      }

   }

   private void setGameOver(boolean gameOver) {
      boolean oldValue = this.gameOver;
      boolean newValue = gameOver;
      this.gameOver = gameOver;
      pcSupport.firePropertyChange(GAME_OVER, oldValue, newValue);
   }

   public void addPropertyChangeListener(PropertyChangeListener listener) {
      pcSupport.addPropertyChangeListener(listener);
   }

   public void removePropertyChangeListener(PropertyChangeListener listener) {
      pcSupport.removePropertyChangeListener(listener);
   }

   public void addPropertyChangeListener(String name,
         PropertyChangeListener listener) {
      pcSupport.addPropertyChangeListener(name, listener);
   }

   public void removePropertyChangeListener(String name,
         PropertyChangeListener listener) {
      pcSupport.removePropertyChangeListener(name, listener);
   }

}

enum XO {
   X("X"), O("O"), BLANK("   ");
   private String text;

   private XO(String text) {
      this.text = text;
   }

   public String getText() {
      return text;
   }
}

我視圖的ActionListener（在這里是AbstractAction）通知引擎某個按鈕已被按下。 引擎跟蹤按下了哪個按鈕，並在確定獲勝者時設置gameOver字段，從而通知所有聽眾游戲已結束。