在ActionListener裏面引用點擊JButton

Question

我想用swing寫一個Tic Tac Toe程序，但是我似乎遇到了一些麻煩。在我的匿名內部類中，我嘗試爲每個按鈕設置actionListener，但是我無法找到允許我引用按鈕並將它們設置爲X或Y的類型或變量。我嘗試了e .getSource（）。setText（）在我的匿名類中，但返回錯誤。有什麼想法嗎？ 謝謝！ 亞歷

import javax.swing.*; 

import java.awt.*; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 

public class TicTacToe { 

public JFrame frame; 
public JLabel label; 
public JPanel panel; 

public static int counter; 



public void go() 
{ 
    frame = new JFrame("TicTacToe"); 
    frame.setSize(500, 500); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    panel = new JPanel(); 
    panel.setLayout(new GridLayout(3,3,10,10)); 
    frame.add(BorderLayout.CENTER, panel); 
    label= new JLabel("TIC TAC TOE"); 
    frame.add(BorderLayout.NORTH, label); 

    ; 


    JButton button1 = new JButton("Button 1"); 
    JButton button2 = new JButton("Button 1"); 
    JButton button3 = new JButton("Button 1"); 
    JButton button4 = new JButton("Button 1"); 
    JButton button5 = new JButton("Button 1"); 
    JButton button6 = new JButton("Button 1"); 
    JButton button7 = new JButton("Button 1"); 
    JButton button8 = new JButton("Button 1"); 
    JButton button9 = new JButton("Button 1"); 





    button1.addActionListener(new ActionListener(){ 
     public void actionPerformed(ActionEvent e) 
     { 


     } 
    }); 

    button2.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 

     } 
    }); 

    button3.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 

     } 
    }); 

    button4.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 

     } 
    }); 

    button5.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 

     } 
    }); 

    button6.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 

     } 
    }); 

    button7.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 

     } 
    }); 

    button8.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 

     } 
    }); 

    button9.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) 
     { 

     } 
    }); 

    panel.add(button1); 
    panel.add(button2); 
    panel.add(button3); 
    panel.add(button4); 
    panel.add(button5); 
    panel.add(button6); 
    panel.add(button7); 
    panel.add(button8); 
    panel.add(button9); 
    frame.setVisible(true); 
    panel.setVisible(true); 

} 


public static void main(String[] args) 
{ 
    TicTacToe gui = new TicTacToe(); 
    gui.go(); 

} 


} 

Answer 1

記住，ActionListener可以在許多不同類型的組件中使用，所以源參考被一般化。你需要轉換爲回期望值

button9.addActionListener(new ActionListener() { 
    public void actionPerformed(ActionEvent e) 
    { 
     Object source = e.getSource(); 
     if (source instanceof JButton) { 
      JButton btn = (JButton)source; 
      // Go ahead and do what you like 
     } 
    } 
}); 

雖然我知道你ActionListener，因爲它代表幾乎可以保證該Object的源類型將是一個JButton，我從來不喜歡盲目地轉換對象，但是這我

Answer 2

如果您收到錯誤，那麼你應該發佈它們，但我假設這是因爲你沒有斷言源對象實際上是一個按鈕。對於你正在做的事情有兩個直接的解決方案。

第一個是因爲您只是爲每個按鈕添加一個動作偵聽器，您可以假定它是動作事件引用的對象。只要注意，按鈕要麼必須是一個實例變量或聲明爲final：

button1.addActionListener(new ActionListener(){ 
     @Override 
     public void actionPerformed(ActionEvent e) 
     { 
      button1.setText("X/Y"); 
     } 
    }); 

其次，這將解決您的錯誤的原因，是聲稱ActionEvent源對象其實是一個按鈕。

button1.addActionListener(new ActionListener() { 
     @Override 
     public void actionPerformed(ActionEvent e) { 
      if (e.getSource() instanceof JButton) { 
       ((JButton) e.getSource()).setText("X/Y"); 
      } 
     } 
    }); 

Answer 3

我經歷了和清理你的代碼一點點：這是通過檢查源是JButton的實例來完成。我不太清楚爲什麼你的代碼有錯誤，但我沒有得到任何答案。我建議，因爲你有共同的代碼，像我在數組中一樣重用它。我還添加了一個boolean在每次點擊按鈕時在玩家之間切換。

最後，我建議在構造函數中或在構造函數調用的私有方法中設置JFrame（更復雜的用戶界面可能有很多代碼，並且分解代碼是維護代碼的好習慣）就像我下面展示的那樣。

import javax.swing.*; 

import java.awt.*; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 

public class TicTacToe { 
    public static final boolean PLAYER_X = false; 
    public static final boolean PLAYER_O = true; 

    public static int counter; 

    private JFrame frame; 
    private JLabel label; 
    private JPanel panel; 
    private JButton[] buttons; 
    private boolean player; 

    public TicTacToe() { 
     frame = new JFrame("TicTacToe"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

     panel = new JPanel(); 
     panel.setPreferredSize(new Dimension(500, 500)); 
     panel.setLayout(new GridLayout(3, 3, 10, 10)); 
     frame.add(BorderLayout.CENTER, panel); 

     label = new JLabel("TIC TAC TOE"); 
     frame.add(BorderLayout.NORTH, label); 

     /* Set the initial player turn to player X */ 
     player = PLAYER_X; 

     /* Create the JButtons */ 
     buttons = new JButton[9]; 

     /* Loop through and set all of them up */ 
     for (int i = 0; i < buttons.length; i++) { 
      buttons[i] = new JButton(); 
      buttons[i].addActionListener(new ActionListener() { 
       @Override 
       public void actionPerformed(ActionEvent e) { 
        if (e.getSource() instanceof JButton) { 
         ((JButton)e.getSource()).setText(player ? "O" : "X"); /* Set button text */ 
         player = !player; /* Switch turns */ 
        } 
       } 
      }); 

      /* Add all of the buttons to the panel. */ 
      panel.add(buttons[i]); 
     } 

     /* Pack the frame to the contents. Basically a "fit to contents". */ 
     frame.pack(); 
    } 

    public void go() { 
     frame.setVisible(true); 
     panel.setVisible(true); 
    } 

    public static void main(String[] args) { 
     TicTacToe gui = new TicTacToe(); 
     gui.go(); 
    } 
}