Disable input some symbols to JTextField

Question

How can I disable input of any symbol except digits to JTextField?

Answer 1

For a better user experience

Others have mentioned the use of JFormattedTextField or KeyListeners to prevent invalid data from being entered but from a usability point of view I find it very annoying to start typing into a field and nothing happens.

To provide a better user experience you can allow the user to enter non-numeric values in the field but use a validator to provide feedback to the user and disable the submit button.

Answer 2

You can add a custom KeyListener that intercepts key strokes and doesn't propogate invalid key strokes to the JTextField.

Answer 3

How to Use Formatted Text Fields

 amountField = new JFormattedTextField(NumberFormat.getIntegerInstance());

You can also create your own format to customize.

Answer 4

The answer is JFormattedTextField. See my answer on this duplicate question:

You can use a JFormattedTextField. Construct it using a NumberFormatter and it will only accept numbers.

The JFormattedTextField has a bunch of configurable options that let you decide how bad input is handled. I recommend looking at the documentation.

Answer 5

Just consume all chars that is not a digit like this:

public static void main(String[] args) {
    JFrame frame = new JFrame("Test");

    frame.add(new JTextField() {{
        addKeyListener(new KeyAdapter() {
            public void keyTyped(KeyEvent e) {
                if (!Character.isDigit(e.getKeyChar()))
                    e.consume();
            }
        });
    }});

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 300);
    frame.setVisible(true);
}

Answer 6

Option 1) change your JTextField with a JFormattedTextField, like this:

try {
   MaskFormatter mascara = new MaskFormatter("##.##");
   JFormattedTextField textField = new JFormattedTextField(mascara);
   textField.setValue(new Float("12.34"));
} catch (Exception e) {
   ...
}

Option 2) capture user's input from keyboard, like this:

JTextField textField = new JTextField(10);
textField.addKeyListener(new KeyAdapter() {
   public void keyTyped(KeyEvent e) {
      char c = e.getKeyChar();
      if ( ((c < '0') || (c > '9')) && (c != KeyEvent.VK_BACK_SPACE)) {
         e.consume();  // ignore event
      }
   }
});