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Allowing the "Enter" key to press the submit button, as opposed to only using MouseClick

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).

NamePromptenter image description here

This is my code:

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);      }   } 

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) {      } } 
like image 498
CodyBugstein Avatar asked Dec 05 '12 20:12

CodyBugstein


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How do I trigger a JButton with a key press?

How to trigger a JButton with a key press? Add an ActionListener to the button. It will fire an event when the button is in focus and the user presses the enter key.

How do I use KeyListener?

A Simple KeyListener Java ClassCreate a new KeyListener object. Override the methods that correspond to the key events you want to monitor e.g keyPressed , keyReleased , keyTyped . Create a JTextField component. Use it's addKeyListener method to add to it the KeyListener you've created.

What is KeyListener in Java?

The listener interface for receiving keyboard events (keystrokes). The class that is interested in processing a keyboard event either implements this interface (and all the methods it contains) or extends the abstract KeyAdapter class (overriding only the methods of interest).


1 Answers

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

frame.getRootPane().setDefaultButton(submitButton); 

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.


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());     }  } 

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); 
like image 129
Martijn Courteaux Avatar answered Oct 06 '22 01:10

Martijn Courteaux