CODEWITHSUNDEEP
javaswingjtextfieldkeylistenerdocumentfilter
user1828622
user1828622

Reputation: 11

Symbols validation in JTextField

What I want to do is when we are going to type something inside the TextField, it should not allow symbols. How to exclude symbols?

The code I used: 

 if (evt.getKeyChar()=='&'||evt.getKeyChar()=='@') {
       jTextField2.setText("");
    }

Upvotes: 0

Views: 365

Answers (2)

gmatagmis
gmatagmis

Reputation: 70

JFormattedTextField

it has two properties instead of one in JTextField :

(1) String "text" shows and (2) any Class "value"

All you need is to put a formatter which converts stringToValue(), and valueToString()

import java.text.ParseException;
import javax.swing.JFormattedTextField;
import javax.swing.text.DefaultFormatter;
import javax.swing.text.JTextComponent;

...

  DefaultFormatter formatter = new DefaultFormatter() {
    {
      setValueClass(String.class); // property "value" of String.class
      setAllowsInvalid(false); // doesnt matter in current example, but very usefull
      setCommitsOnValidEdit(true); // convert value back to text after every valid edit
    }
    @Override
    public Object stringToValue(String string) throws ParseException {
      string = string.replace("&","").replace("@","");
      return string;
    }
  };

  JTextComponent txt = new JFormattedTextField(formatter);

plus you can

  txt.addPropertyChangeListener("value", yourPropertyChangeListener);

to get value instantly after change

Upvotes: 2

Guillaume Polet
Guillaume Polet

Reputation: 47617

You should use a DocumentFilter. Here is a very simple/basic demo example:

import java.awt.FlowLayout;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;

public class TestDocumentFilter {

    private void initUI() {
        JFrame frame = new JFrame(TestDocumentFilter.class.getSimpleName());
        frame.setLayout(new FlowLayout());
        final JTextField textfield = new JTextField(20);
        ((AbstractDocument) textfield.getDocument()).setDocumentFilter(new DocumentFilter() {
            @Override
            public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException {
                string = string.replace("&", "").replace("@", "");
                super.insertString(fb, offset, string, attr);
            }

            @Override
            public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
                text = text.replace("&", "").replace("@", "");
                super.replace(fb, offset, length, text, attrs);
            }
        });
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(textfield);
        frame.setSize(300, 300);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TestDocumentFilter().initUI();
            }
        });
    }

}

Upvotes: 6

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