来自另一个类的JButton操作侦听器

Question

我正在处理JButton事件。我有一个JPanel类，我们叫Panel1，包含一个公共的JButton，我们叫它Button1。单击此按钮时：

//Inside Panel1
Button1.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent e)
   {
      System.out.println("1")
   }
});

//Inside Panel2
Panel1.Button1.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent e)
   {
      System.out.println("2")
   }
});

2
1

但我有兴趣：

1
2

有什么建议吗？

Answer 1

如果您将ActionListeners添加到JButton中，您无法保证它们将触发的顺序，并且知道添加的顺序并不能保证有帮助。解决这一问题的一种方法是使用ActionListener更改对象的状态，然后监听该状态。这将保证ActionListener首先触发。

例如，使用PropertyChangeListener作为第二个侦听器：

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.*;

public class ActionOrder extends JPanel {
   ButtonPanel buttonPanel = new ButtonPanel();
   OtherPanel otherPanel = new OtherPanel();

   public ActionOrder() {
      add(buttonPanel);
      add(otherPanel);

      buttonPanel.addPropertyChangeListener(ButtonPanel.PRESSED, new PropertyChangeListener() {

         @Override
         public void propertyChange(PropertyChangeEvent evt) {
            otherPanel.appendText("Button 1 Pressed");
         }
      });
   }

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

      JFrame frame = new JFrame("ActionOrder");
      frame.setDefaultCloseOperation(JFrame.DISPOSE_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();
         }
      });
   }
}


class ButtonPanel extends JPanel {
   public static final String PRESSED = "pressed";
   private JButton button1 = new JButton("Button 1");

   public ButtonPanel() {
      add(button1);
      button1.addActionListener(new ActionListener() {

         @Override
         public void actionPerformed(ActionEvent e) {
            System.out.println("1");
            firePropertyChange(PRESSED, null, PRESSED);
         }
      });

      setBorder(BorderFactory.createTitledBorder("Button Panel"));
   }
}

class OtherPanel extends JPanel {
   private JTextArea textArea = new JTextArea(10, 20);

   public OtherPanel() {
      add(new JScrollPane(textArea));
      setBorder(BorderFactory.createTitledBorder("Other Panel"));
   }

   public void appendText(String text) {
      textArea.append(text + "\n");
      System.out.println("2");
      System.out.println();
   }
}