A DocumentListener as a functional interface. This interface aggregates all default methods of a DocumentListener to a single method. This is usefull if you don't care about the type of change in a JTextComponent.

SimpleDocumentListener.java

//
// Attribution 4.0 International (CC BY 4.0) 
// https://creativecommons.org/licenses/by/4.0/
//
// Original location:
// https://gist.github.com/nigjo/d14a29eab90a0a55f62228c2c71ecb03
//
package com.github.gist.nigjo;

import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;

/**
 * A DocumentListener as a functional interface. This interface aggregates all default
 * methods of a DocumentListener to a single method. This is usefull if you don't care
 * about the type of change in a JTextComponent.
 *
 * <pre>textfield.getDocument().addDocumentListener(
 *  (SimpleDocumentListener)this::textChangeHandlerMethod);</pre>
 *
 * @author Jens Hofschröer
 */
@FunctionalInterface
public interface SimpleDocumentListener extends DocumentListener
{

  /**
   * Gives notification of any change of the text of the document. Check the type of the
   * event to determinate what kind of change this was. See the default documentation of
   * {@link DocumentListener} for event details.
   *
   * @param e the document event
   */
  public void textChanged(DocumentEvent e);

  @Override
  public default void insertUpdate(DocumentEvent e)
  {
    textChanged(e);
  }

  @Override
  public default void changedUpdate(DocumentEvent e)
  {
    textChanged(e);
  }

  @Override
  public default void removeUpdate(DocumentEvent e)
  {
    textChanged(e);
  }

}