java swing JCombox上的箭头事件怎么触发

[zhangshenqiu]

java swing JCombox上的向下箭头事件怎么触发，用什么监听事件 的？我只要单击那个箭头就想处理一个动作。各位帮帮忙

[一洽客服系统]

应该actionlistener就能满足你的需求吧

[swandragon]

ActionListener actionListener = new ActionListener() {
public void actionPerformed(ActionEvent actionEvent) {

}
};

public static void main(String args[]) {
    String labels[] = { "A", "B", "C", "D","E", "F", "G", "H","I", "J" };
    JFrame frame = new JFrame("Editable JComboBox");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = frame.getContentPane();

    final JComboBox comboBox = new JComboBox(labels);
    comboBox.setMaximumRowCount(5);
    comboBox.setEditable(true);
    contentPane.add(comboBox, BorderLayout.NORTH);

    final JTextArea textArea = new JTextArea();
    JScrollPane scrollPane = new JScrollPane(textArea);
    contentPane.add(scrollPane, BorderLayout.CENTER);

    ActionListener actionListener = new ActionListener() {
      public void actionPerformed(ActionEvent actionEvent) {
        textArea.append("Selected: " + comboBox.getSelectedItem());
        textArea.append(", Position: " + comboBox.getSelectedIndex());
        textArea.append(System.getProperty("line.separator"));
      }
    };
    comboBox.addActionListener(actionListener);

    frame.setSize(300, 200);
    frame.setVisible(true);
  }

[zhangshenqiu]

单击箭头，是触发不了那个ActionListener吧？我试过了。不行啊

[plplum]

import javax.swing.JOptionPane;


public class NewJFrame2 extends javax.swing.JFrame {

    /** Creates new form NewJFrame2 */
    public NewJFrame2() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jComboBox1 = new javax.swing.JComboBox();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));
        jComboBox1.addPopupMenuListener(new javax.swing.event.PopupMenuListener() {
            public void popupMenuCanceled(javax.swing.event.PopupMenuEvent evt) {
            }
            public void popupMenuWillBecomeInvisible(javax.swing.event.PopupMenuEvent evt) {
            }
            public void popupMenuWillBecomeVisible(javax.swing.event.PopupMenuEvent evt) {
                jComboBox1PopupMenuWillBecomeVisible(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(100, 100, 100)
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 156, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(144, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(84, 84, 84)
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(246, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>

    private void jComboBox1PopupMenuWillBecomeVisible(javax.swing.event.PopupMenuEvent evt) {
          JOptionPane.showMessageDialog(null, "事件触发！");
    }

    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new NewJFrame2().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JComboBox jComboBox1;
    // End of variables declaration

}

[littlemonster]

import java.awt.BorderLayout;
import java.awt.ItemSelectable;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JComboBox;
import javax.swing.JFrame;

public class MainClass {

public static void main(final String args[]) {
final String labels[] = { "A", "B", "C", "D", "E" };
JFrame frame = new JFrame("Selecting JComboBox");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

JComboBox comboBox = new JComboBox(labels);
frame.add(comboBox, BorderLayout.SOUTH);

ActionListener actionListener = new ActionListener() {
public void actionPerformed(ActionEvent actionEvent) {
System.out.println("Command: " + actionEvent.getActionCommand());
ItemSelectable is = (ItemSelectable)actionEvent.getSource();
System.out.println(", Selected: " + selectedString(is));
}
};
comboBox.addActionListener(actionListener);
frame.setSize(400, 200);
frame.setVisible(true);

}
static private String selectedString(ItemSelectable is) {
Object selected[] = is.getSelectedObjects();
return ((selected.length == 0) ? "null" : (String)selected[0]);
}
}

[qingzhe2008]

comboBox.addPopupMenuListener(new PopupMenuListener(){

			public void popupMenuCanceled(PopupMenuEvent e) {
				// 下拉选项弹出时，按ESC键会触发
				System.out.println("popupMenuCanceled");
				
			}

			public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
				// 点击箭头，下拉选项消失时触发
				System.out.println("popupMenuWillBecomeInvisible");
			}

			public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
				// 点击箭头，下拉选项弹出时触发
				System.out.println("popupMenuWillBecomeVisible");
				
			}
	    	
	    });

[睡觉谁叫~~~]

学习了！