允许“输入"按下提交按钮的键，而不是仅使用 MouseClick

允许“输入

问题描述：

我现在正在学习 Swing 课程以及有关它的所有内容.我有这个玩具程序，我一直在组合它，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被点击，但我也想让它与 Enter 按钮一起工作.我已经尝试添加 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.

I'm learning Swing class now and everything about it. I've got this toy program I've been putting together that prompts for a name and then presents a JOptionPane with the message "You've entered (Your Name)". The submit button I use can only be clicked on, but I'd like to get it to work with the Enter button too. I've tried adding a KeyListener, as is recommended in the Java book I'm using (Eventful Java, Bruce Danyluk and Murtagh).

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:

And this is the actionListener, keyListener class:

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) {

    }
}

答

对此有一个简单的技巧.在使用所有按钮构建框架后，请执行以下操作:

There is a simple trick for this. After you constructed the frame with all it buttons do this:

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(可能还有一些我不知道的其他事件).当您在该帧中按 Enter 键时，将调用 ActionListeners 的 actionPerformed() 方法.

For each frame, you can set a default button that will automatically listen to the Enter key (and maybe some other event's I'm not aware of). When you hit enter in that frame, the ActionListeners their actionPerformed() method will be invoked.

据我所知，你的代码的问题是每次你按下一个键时你的对话框都会弹出，因为你没有把它放在 if-body 中.尝试将其更改为:

And the problem with your code as far as I see is that your dialog pops up every time you hit a key, because you didn't put it in the if-body. Try changing it to this:

@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.您正在将密钥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:

UPDATE: I found what is wrong with your code. You are adding the key listener to the Submit button instead of to the TextField. Change your code to this:

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

允许“输入"按下提交按钮的键，而不是仅使用 MouseClick

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