Listening to JTextField Events with a DocumentListener : DocumentListener « Swing Event « Java Tutorial

1. Java Tutorial
2. Swing Event
3. DocumentListener

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.Document;

public class AddingDocumentListenerJTextFieldSample {
  public static void main(String args[]) {
    final JFrame frame = new JFrame("Default Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JTextField textField = new JTextField();
    frame.add(textField, BorderLayout.NORTH);

    DocumentListener documentListener = new DocumentListener() {
      public void changedUpdate(DocumentEvent documentEvent) {
        printIt(documentEvent);
      }
      public void insertUpdate(DocumentEvent documentEvent) {
        printIt(documentEvent);
      }
      public void removeUpdate(DocumentEvent documentEvent) {
        printIt(documentEvent);
      }
      private void printIt(DocumentEvent documentEvent) {
        DocumentEvent.EventType type = documentEvent.getType();
        String typeString = null;
        if (type.equals(DocumentEvent.EventType.CHANGE)) {
          typeString = "Change";
        }  else if (type.equals(DocumentEvent.EventType.INSERT)) {
          typeString = "Insert";
        }  else if (type.equals(DocumentEvent.EventType.REMOVE)) {
          typeString = "Remove";
        }
        System.out.print("Type : " + typeString);
        Document source = documentEvent.getDocument();
        int length = source.getLength();
        System.out.println("Length: " + length);
      }
    };
    textField.getDocument().addDocumentListener(documentListener);
    
    frame.setSize(250, 150);
    frame.setVisible(true);
  }
}

15.13.DocumentListener
	15.13.1.	How to Write a Document Listener
	15.13.2.	Get document from DocumentListener
	15.13.3.	Listening to JTextField Events with a DocumentListener
	15.13.4.	DocumentListener and DocumentEvent