Bounded TextField : TextField « Swing JFC « Java

Bounded TextField

Bounded TextField

Core SWING Advanced Programming 
By Kim Topley
ISBN: 0 13 083292 8       
Publisher: Prentice Hall  

import java.awt.Toolkit;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.PlainDocument;

public class BoundedTextField extends JTextField implements
    BoundedPlainDocument.InsertErrorListener {
  public BoundedTextField() {
    this(null, 0, 0);

  public BoundedTextField(String text, int columns, int maxLength) {
    super(null, text, columns);

    if (text != null && maxLength == 0) {
      maxLength = text.length();
    BoundedPlainDocument plainDoc = (BoundedPlainDocument) getDocument();


  public BoundedTextField(int columns, int maxLength) {
    this(null, columns, maxLength);

  public BoundedTextField(String text, int maxLength) {
    this(text, 0, maxLength);

  public void setMaxLength(int maxLength) {
    ((BoundedPlainDocument) getDocument()).setMaxLength(maxLength);

  public int getMaxLength() {
    return ((BoundedPlainDocument) getDocument()).getMaxLength();

  // Override to handle insertion error
  public void insertFailed(BoundedPlainDocument doc, int offset, String str,
      AttributeSet a) {
    // By default, just beep

  // Method to create default model
  protected Document createDefaultModel() {
    return new BoundedPlainDocument();

  // Test code
  public static void main(String[] args) {
    try {
    } catch (Exception evt) {}
    JFrame f = new JFrame("Bounded Text Field Example");
    BoundedTextField tf = new BoundedTextField(10, 32);
    JLabel l = new JLabel("Type up to 32 characters: ");
    f.getContentPane().add(tf, "East");
    f.getContentPane().add(l, "West");

class BoundedPlainDocument extends PlainDocument {
  public BoundedPlainDocument() {
    // Default constructor - must use setMaxLength later
    this.maxLength = 0;

  public BoundedPlainDocument(int maxLength) {
    this.maxLength = maxLength;

  public BoundedPlainDocument(AbstractDocument.Content content, int maxLength) {
    if (content.length() > maxLength) {
      throw new IllegalArgumentException(
          "Initial content larger than maximum size");
    this.maxLength = maxLength;

  public void setMaxLength(int maxLength) {
    if (getLength() > maxLength) {
      throw new IllegalArgumentException(
          "Current content larger than new maximum size");

    this.maxLength = maxLength;

  public int getMaxLength() {
    return maxLength;

  public void insertString(int offset, String str, AttributeSet a)
      throws BadLocationException {
    if (str == null) {

    // Note: be careful here - the content always has a
    // trailing newline, which should not be counted!
    int capacity = maxLength + 1 - getContent().length();
    if (capacity >= str.length()) {
      // It all fits
      super.insertString(offset, str, a);
    } else {
      // It doesn't all fit. Add as much as we can.
      if (capacity > 0) {
        super.insertString(offset, str.substring(0, capacity), a);

      // Finally, signal an error.
      if (errorListener != null) {
        errorListener.insertFailed(this, offset, str, a);

  public void addInsertErrorListener(InsertErrorListener l) {
    if (errorListener == null) {
      errorListener = l;
    throw new IllegalArgumentException(
        "InsertErrorListener already registered");

  public void removeInsertErrorListener(InsertErrorListener l) {
    if (errorListener == l) {
      errorListener = null;

  public interface InsertErrorListener {
    public abstract void insertFailed(BoundedPlainDocument doc, int offset,
        String str, AttributeSet a);

  protected InsertErrorListener errorListener; // Unicast listener

  protected int maxLength;


Related examples in the same category

1.Make a Text Field two columns wide
2.Water mark text field
3.Auto complete TextField
4.Text fields and Java eventsText fields and Java events
5.JTextField Alignment SampleJTextField Alignment Sample
6.Create the textfieldCreate the textfield
7.FieldEdit - an Applet to validate data as it's being entered
8.Textfield only accepts numbersTextfield only accepts numbers
9.Overwritable TextFieldOverwritable TextField
10.Numeric TextFieldNumeric TextField
11.Passive TextField 1Passive TextField 1
12.Passive TextField 2Passive TextField 2
13.Text Accelerator ExampleText Accelerator Example
14.TextField Look Ahead ExampleTextField Look Ahead Example
15.Passive TextField 3Passive TextField 3
16.Non Wrapping(Wrap) TextPaneNon Wrapping(Wrap) TextPane
18.TextField ElementsTextField Elements
19.TextFieldViews 2TextFieldViews 2
20.TextField with ConstaintsTextField with Constaints
21.JTextField Sample 2JTextField Sample 2
22.JTextField Verifier SampleJTextField Verifier Sample
23.A simple label for field form panelA simple label for field form panel
24.A hack to make a JTextField really 2 columns wideA hack to make a JTextField really 2 columns wide
25.Limit JTextField input to a maximum length
26.Make sure that my JTextField has the focus when a JFrame is created
27.Make the ENTER key act like the TAB key
28.Setting up a textfield and modifying its horizontal alignment at runtimeSetting up a textfield and modifying its horizontal alignment at runtime
29.Aligning the Text in a JTextField Component
30.Based on JTextField content, enable or disable a JButton
31.Cut, paste, and copy in a JTextField under program control.
32.Add key listener event handler to JTextField
33.Right justified JTextfield content
34.Set the focus on a particular JTextField
35.Associate JLabel component with a JTextField
36.Right justified JTextField contents
37.Validate a value on the lostFocus event
38.Modify horizontal alignment of text field at runtime
39.Make sure that my Text field has the focus when a JFrame is created
40.Firing Item Events
41.extends JTextField to create integer JTextField
42.JTextField Max Length
43.Demo for three types of text component: JTextField, JPasswordField, JTextArea