How to allow date input in yyyy-MM-dd format without external libraries?

I'm building a Java Swing application where users need to enter a date in the format yyyy-MM-dd.

I want to use only standard Swing and Java components, without external libraries like JCalendar or JDateChooser.

The date values I'm working with are of type java.sql.Date. If needed, I can convert from java.util.Date. I'm using NetBeans GUI Builder to design the form visually I used java.sql.date because it is the type of data that would be needed to then make the query towards the database

I tried

1. JFormattedTextField with a DateFormatter and yyyy-MM-dd pattern

2. Works, but requires the user to manually type the dashes, or parsing fails.

3. MaskFormatter ("####-##-##")

4. Enforces the visual format but accepts invalid dates like 3202-15-59.

MaskFormatter can do it. You just need to override its stringToValue method, so it disallows invalid dates:

import java.time.LocalDate;
import java.time.format.DateTimeParseException;
import java.text.ParseException;
import java.io.Serial;
import javax.swing.text.MaskFormatter;

public class DateFormatter
extends MaskFormatter {
    @Serial
    private static final long serialVersionUID = 1;

    @SuppressWarnings("this-escape")
    public DateFormatter() {
        try {
            setMask("####-##-##");
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
        setPlaceholder("\u2007");
    }

    @Override
    public Object stringToValue(String text)
    throws ParseException {
        try {
            return LocalDate.parse(text);
        } catch (DateTimeParseException e) {
            ParseException pe = new ParseException(text, e.getErrorIndex());
            pe.initCause(e);
            throw pe;
        }
    }
}

And as many others have mentioned, avoid using java.sql.Date. All JDBC drivers can use java.time.LocalDate for reading and writing SQL Date values.