允许“Enter”键按下提交按钮，而不是仅使用 MouseClick

Question

我现在正在学习 Swing 课程以及有关它的一切。我有一个我一直在整理的玩具程序，它会提示输入名称，然后显示一个带有消息“您已输入（您的姓名）”的 JOptionPane。 我使用的提交按钮只能单击，但我也想让它与 Enter 按钮一起使用。我尝试添加一个 KeyListener，正如我正在使用的 Java 书籍（Eventful Java、Bruce Danyluk 和 Murtagh）中所推荐的那样。

这是我的代码：

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

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;


public class NamePrompt extends JFrame{


    private static final long serialVersionUID = 1L;

    String name;

    public NamePrompt(){

        setLayout(new BorderLayout());

        JLabel enterYourName = new JLabel("Enter Your Name Here:");
        JTextField textBoxToEnterName = new JTextField(21);
        JPanel panelTop = new JPanel();
        panelTop.add(enterYourName);
        panelTop.add(textBoxToEnterName);

        JButton submit = new JButton("Submit");
        submit.addActionListener(new SubmitButton(textBoxToEnterName));
        submit.addKeyListener(new SubmitButton(textBoxToEnterName));
        JPanel panelBottom = new JPanel();
        panelBottom.add(submit);

        //Add panelTop to JFrame
        add(panelTop, BorderLayout.NORTH);
        add(panelBottom, BorderLayout.SOUTH);

        //JFrame set-up
        setTitle("Name Prompt Program");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        pack();
        setLocationRelativeTo(null);


    }



    public static void main(String[] args) {
        NamePrompt promptForName = new NamePrompt();
        promptForName.setVisible(true); 
    }


}

这是actionListener，keyListener类：

import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;


public class SubmitButton implements ActionListener, KeyListener {

    JTextField nameInput;


    public SubmitButton(JTextField textfield){
        nameInput = textfield;
    }

    @Override
    public void actionPerformed(ActionEvent submitClicked) {

        Component frame = new JFrame();
        JOptionPane.showMessageDialog(frame , "You've Submitted the name " + nameInput.getText());
    }

    @Override
    public void keyPressed(KeyEvent e) {
        if (e.getKeyCode()==KeyEvent.VK_ENTER){
            System.out.println("Hello");
        }
        Component frame = new JFrame();
        JOptionPane.showMessageDialog(frame , "You've Submitted the name " + nameInput.getText());

    }

    @Override
    public void keyReleased(KeyEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void keyTyped(KeyEvent arg0) {

    }
}

Answer 1

textField_in = new JTextField();
textField_in.addKeyListener(new KeyAdapter() {

    @Override
    public void keyPressed(KeyEvent arg0) {
        System.out.println(arg0.getExtendedKeyCode());
        if (arg0.getKeyCode()==10) {
            String name = textField_in.getText();
            textField_out.setText(name);
        }

    }

});
textField_in.setBounds(173, 40, 86, 20);
frame.getContentPane().add(textField_in);
textField_in.setColumns(10);

Answer 2

我知道这不是最好的方法，但是右键单击有问题的按钮、事件、键、键入的键。这是一种简单的方法，但对任何键都有反应

Answer 3

没有框架，这对我有用：

JTextField tf = new JTextField(20);
tf.addKeyListener(new KeyAdapter() {

  public void keyPressed(KeyEvent e) {
    if (e.getKeyCode()==KeyEvent.VK_ENTER){
       SwingUtilities.getWindowAncestor(e.getComponent()).dispose();
    }
  }
});
String[] options = {"Ok", "Cancel"};
int result = JOptionPane.showOptionDialog(
    null, tf, "Enter your message", 
    JOptionPane.OK_CANCEL_OPTION,
    JOptionPane.QUESTION_MESSAGE,
    null,
    options,0);

message = tf.getText();

Answer 4

在 ActionListener 类中你可以简单地添加

public void actionPerformed(ActionEvent event) {
    if (event.getSource()==textField){
        textButton.doClick();
    }
    else if (event.getSource()==textButton) {
        //do something
    }
}

Answer 5

 switch(KEYEVENT.getKeyCode()){
      case KeyEvent.VK_ENTER:
           // I was trying to use case 13 from the ascii table.
           //Krewn Generated method stub... 
           break;
 }

Answer 6

您可以使用顶级容器根窗格设置默认按钮，这将允许它响应输入。

SwingUtilities.getRootPane(submitButton).setDefaultButton(submitButton);

当然，这假设您已将按钮添加到有效容器中；）

更新

这是一个使用 JRootPane#setDefaultButton 和键绑定 API 的基本示例

public class DefaultButton {

    public static void main(String[] args) {
        new DefaultButton();
    }

    public DefaultButton() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }

        });
    }

    public class TestPane extends JPanel {

        private JButton button;
        private JLabel label;
        private int count;

        public TestPane() {

            label = new JLabel("Press the button");
            button = new JButton("Press me");

            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridy = 0;
            add(label, gbc);
            gbc.gridy++;
            add(button, gbc);
            gbc.gridy++;
            add(new JButton("No Action Here"), gbc);

            button.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    doButtonPressed(e);
                }

            });

            InputMap im = button.getInputMap(WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
            ActionMap am = button.getActionMap();

            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0), "spaced");
            am.put("spaced", new AbstractAction() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    doButtonPressed(e);
                }

            });

        }

        @Override
        public void addNotify() {
            super.addNotify();
            SwingUtilities.getRootPane(button).setDefaultButton(button);
        }

        protected void doButtonPressed(ActionEvent evt) {
            count++;
            label.setText("Pressed " + count + " times");
        }

    }

}

当然，这假设具有焦点的组件不消耗有问题的键事件（如第二个按钮消耗 space 或 enter 键

Answer 7

有一个简单的技巧。在您使用所有按钮构建框架后，请执行以下操作：

frame.getRootPane().setDefaultButton(submitButton);

对于每一帧，您可以设置一个默认按钮，该按钮将自动侦听 Enter 键（可能还有其他一些我不知道的事件）。当您在该帧中按 Enter 键时，将调用 ActionListener 的 actionPerformed() 方法。

---

据我所知，您的代码的问题是每次您按下一个键时都会弹出对话框，因为您没有将它放在 if-body 中。尝试将其更改为：

@Override
public void keyPressed(KeyEvent e) {
    if (e.getKeyCode()==KeyEvent.VK_ENTER){
        System.out.println("Hello");

        JOptionPane.showMessageDialog(null , "You've Submitted the name " + nameInput.getText());
    }

}

---

更新：我发现您的代码有什么问题。您将关键侦听器添加到提交按钮而不是文本字段。将您的代码更改为：

SubmitButton listener = new SubmitButton(textBoxToEnterName);
textBoxToEnterName.addActionListener(listener);
submit.addKeyListener(listener);