Jformattedtextfield is accepting no characters

Question

I have a window where we have a JFomattedTextField called txtQuantia, I applied a mask to him called mskQuantia, and set the valid characters, in this case, 0-9, but this field is not accepting any characters ... What can be ?

MaskFormatter mskQuantia = new MaskFormatter();
mskQuantia.setValidCharacters("0123456789");

JFormattedTextField txtQuantia = new JFormattedTextField(mskQuantia);

Remembering that I didn’t have to put one try/catch to instantiate the mask ...

Answer 1

As you are doing, no masks are being applied in the field. You are just starting the variable mskQuantia, but without any valid mask.

The method setValidCharacters() just filter what you want to be accepted in the mask applied in the field, then we return to the previous paragraph, you are not applying any mask, despite being "installing" the MaskFormatter empty in the field.

This answer on how to do this restriction in Jtextfield may be the most recommended option for the case you want, since there is not so much commitment to mask or formatting what should be typed.

Simply adapt the code by removing the maximum number of characters limitation:

import javax.swing.text.PlainDocument;

class JTextFieldFilter extends PlainDocument {

    JTextFieldLimit() {
        super();
    }

    @Override
    public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException {
        if (str == null) {
            return;
        }
        super.insertString(offset, str.replaceAll("\\D++", ""), attr);
    }
}

The above Code should be applied to JTextField as follows:

seuJTextField.setDocument(new JTextFieldFilter());

Answer 2

You can add a keytyped event.

  private void campoSomenteNumero(java.awt.event.KeyEvent evt) {
   String num = "0123456789";
        if (!num.contains(evt.getKeyChar() + "") {
            evt.consume();
        }
     }

Something like this doesn’t even need to be formatted field.