按下 Enter 键时调用一系列操作

Question

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

动作监听器里面有一个JOptionPane.showMessageDialog()。当按下 Tab 时，选项窗格将显示一条信息消息。

我的问题是，当我在信息消息对话框的确定按钮上按 Enter 时，会调用一系列操作，即 Tab JTextField 和 的操作输入 btnNewButton 的操作。

如果我用鼠标单击“错误消息”对话框的“确定”按钮，一切正常，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 JOptionPane 关闭之后使 btnNewButton 成为焦点组件，因此调用了 keyReleased() 方法 –显示另一个 JOptionPane.

只需将方法重命名为keyPressed()。

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

这是我更正过的代码。

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）不需要显式设置 JFrame 的默认关闭操作，因为默认是 EXIT_ON_CLOSE

按下 Enter 键时调用一系列操作

Invoke a serie of actions when Enter key is pressed

java

swing

keylistener

key-bindings

actionevent