按下 Enter 键时调用一系列操作

Question

我有一个Swing项目，我在JTextField上有一个用于Tab键的动作侦听器，如下所示。

动作侦听器中有一个JOptionPane.showMessageDialog() 。 当按下Tab键时，选项窗格将显示一条信息消息。

我的问题是，当我在 Information Message 对话框的 OK 按钮上按Enter时，调用了一系列操作，即JTextField的Tab操作和btnNewButton的Enter操作。

如果我用鼠标单击错误消息对话框的确定按钮，一切都很好，没有问题。

我可以使用键绑定而不是键侦听器来解决这个问题吗？

请提出解决方案

import java.awt.EventQueue;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.Collections;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

public class Test extends JFrame {
    private JPanel contentPane;
    private JTextField textField;
    private JButton btnNewButton;
    private JDialog dialog;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Test frame = new Test();
                    frame.setVisible(true);
                }
                catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public Test() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        setLocationRelativeTo(null);
        contentPane.setLayout(null);

        textField = new JTextField();
        textField.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
                Collections.emptySet());
        textField.addKeyListener(new java.awt.event.KeyAdapter() {
            public void keyPressed(java.awt.event.KeyEvent evt) {
                if (evt.getKeyCode() == KeyEvent.VK_TAB) {
                    JOptionPane.showMessageDialog(dialog, " Please Press ENTER Key", "information",
                            JOptionPane.INFORMATION_MESSAGE);

                    btnNewButton.grabFocus();
                }
            }
        });
        textField.setBounds(73, 28, 178, 28);
        contentPane.add(textField);
        textField.setColumns(10);

        btnNewButton = new JButton("New button");
        btnNewButton.addKeyListener(new KeyAdapter() {
            @Override
            public void keyReleased(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    JOptionPane.showMessageDialog(dialog, " That Invoked New Button Also", "Error",
                            JOptionPane.ERROR_MESSAGE);
                }
            }
        });
        btnNewButton.setBounds(223, 137, 117, 25);
        contentPane.add(btnNewButton);

        JLabel lblNewLabel = new JLabel("Please Press TAB Key");
        lblNewLabel.setBounds(83, 55, 183, 15);
        contentPane.add(lblNewLabel);

        dialog = new JDialog();
        dialog.setAlwaysOnTop(true);
    }
}

Answer 1

问题是您正在覆盖方法keyReleased() 。 JOptionPane在调用keyReleased()方法之前关闭，并且由于您在关闭JOptionPane之后使btnNewButton成为焦点组件，因此将调用keyReleased()方法——这会显示另一个JOptionPane 。

只需将该方法重命名为keyPressed()即可。

此外，您不需要dialog成员。 JOptionPane#showMessageDialog的第一个参数应该是JFrame 。

这是您的代码和我的更正。

import java.awt.EventQueue;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.Collections;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

public class Test extends JFrame {
    private JPanel contentPane;
    private JTextField textField;
    private JButton btnNewButton;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Test frame = new Test();
                    frame.setVisible(true);
                }
                catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public Test() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        setLocationRelativeTo(null);
        contentPane.setLayout(null);

        textField = new JTextField();
        textField.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
                Collections.emptySet());
        textField.addKeyListener(new java.awt.event.KeyAdapter() {
            public void keyPressed(java.awt.event.KeyEvent evt) {
                if (evt.getKeyCode() == KeyEvent.VK_TAB) {
                    JOptionPane.showMessageDialog(Test.this, " Please Press ENTER Key", "information",
                            JOptionPane.INFORMATION_MESSAGE);
                    btnNewButton.grabFocus();
                }
            }
        });
        textField.setBounds(73, 28, 178, 28);
        contentPane.add(textField);
        textField.setColumns(10);

        btnNewButton = new JButton("New button");
        btnNewButton.addKeyListener(new KeyAdapter() {
            @Override
            public void keyPressed(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    JOptionPane.showMessageDialog(Test.this, " That Invoked New Button Also", "Error",
                            JOptionPane.ERROR_MESSAGE);
                }
            }
        });
        btnNewButton.setBounds(223, 137, 117, 25);
        contentPane.add(btnNewButton);

        JLabel lblNewLabel = new JLabel("Please Press TAB Key");
        lblNewLabel.setBounds(83, 55, 183, 15);
        contentPane.add(lblNewLabel);
    }
}

请注意（至少在 JDK 15 中）无需显式设置JFrame的默认关闭操作，因为默认值为EXIT_ON_CLOSE