CODEWITHSUNDEEP
javaswingjtextfieldkeylistener
user1973528
user1973528

Reputation: 29

update textfield simultaneously with key event without text field

I'm trying to write a program where the user can type in numbers but not letters or symbols. I have a textfield that is not editable because I want only acceptable user input keys to be displayed on the textfield. This is the basic structure of my code.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class SampleProgram extends JFrame implements ActionListener, KeyListener
{
    private Container container;
    private JPanel panel;
    private JTextField textField;
    private JButton button;
    private String[] names = {"1", "2", "3", "4", "5", "6", "7", "8", "9"};

    public SampleProgram()
    {
        container = getContentPane();
        panel = new JPanel();

        textField = new JTextField();
        textField.setEditable(false);
        contain.add(textField);

        addKeyListener(this);

        button = new JButton("Some Action Button");
        button.addActionListener(this);
        panel.add(button);

        container.add(panel);

        setResizable(false);
        setVisible(true);
    }

    public void keyPressed(KeyEvent event) {}
    public void keyReleased(KeyEvent event) {}

    public void keyTyped(KeyEvent event)
    {
        String action = String.valueOf(event.getKeyChar());
        for (String s : names)
            if (action.equalsIgnoreCase(s))
            {
                someAction(action);
                return;
            }
    }

    public void actionPerformed(ActionEvent event)
    {
        String action = ((JButton)event.getSource()).getText();
        someAction(action);
    }

    private void someAction(String input)
    {
        textField.setText(input);
    }

}

This is the stripped down version of my code. My ActionListener is doing what it is supposed to do, but my KeyListener isn't working at all. I tried to add KeyListener to textField as well, but that didn't work either. How do I get my program to read in the user key input? To figure out the error, I tried putting in the code textField.setText(action) in the keyTyped method, and I learned that my code wasn't even entering the keyTyped method.

Upvotes: 1

Views: 810

Answers (1)

camickr
camickr

Reputation: 324147

Use a JFormattedTextField. You can set a MaskFormatter to allow only numeric digits.

Read the section from the Swing tutorial on How to Use Formatted Text Fields for more information and examples.

Upvotes: 2

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