extends JTextField to create integer JTextField : JTextField « Swing « Java Tutorial

1. Java Tutorial
2. Swing
3. JTextField

/*
 * Copyright (C) 2001-2003 Colin Bell
 * colbell@users.sourceforge.net
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
import java.awt.Toolkit;

import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.PlainDocument;
/**
 * This class is a <CODE>TextField</CODE> that only allows integer
 * values to be entered into it.
 *
 * @author <A HREF="mailto:colbell@users.sourceforge.net">Colin Bell</A>
 */
public class IntegerField extends JTextField
{
  /**
   * Default ctor.
   */
  public IntegerField()
  {
    super();
  }

  /**
   * Ctor specifying the field width.
   *
   * @param cols  Number of columns.
   */
  public IntegerField(int cols)
  {
    super(cols);
  }

  /**
   * Retrieve the contents of this field as an <TT>int</TT>.
   *
   * @return  the contents of this field as an <TT>int</TT>.
   */
  public int getInt()
  {
    final String text = getText();
    if (text == null || text.length() == 0)
    {
      return 0;
    }
    return Integer.parseInt(text);
  }

  /**
   * Set the contents of this field to the passed <TT>int</TT>.
   *
   * @param value The new value for this field.
   */
  public void setInt(int value)
  {
    setText(String.valueOf(value));
  }

  /**
   * Create a new document model for this control that only accepts
   * integral values.
   *
   * @return  The new document model.
   */
  protected Document createDefaultModel()
  {
    return new IntegerDocument();
  }

  /**
   * This document only allows integral values to be added to it.
   */
  static class IntegerDocument extends PlainDocument
  {
    public void insertString(int offs, String str, AttributeSet a)
      throws BadLocationException
    {
      if (str != null)
      {
        try
        {
          Integer.decode(str);
          super.insertString(offs, str, a);
        }
        catch (NumberFormatException ex)
        {
          Toolkit.getDefaultToolkit().beep();
        }
      }
    }
  }
}

14.15.JTextField
	14.15.1.	Make a Text Field two columns wide
	14.15.2.	Sharing Data Models between two JTextField
	14.15.3.	Adding ActionListener to JTextField
	14.15.4.	Verifying Input During Focus Traversal
	14.15.5.	JTextField with a JScrollBar for Scrolling
	14.15.6.	Horizontal Alignment
	14.15.7.	Using JLabel Mnemonics: Interconnect a specific JLabel and JTextField
	14.15.8.	To make sure that the end of the contents is visible
	14.15.9.	Use the write() method to write the contents
	14.15.10.	Drag and drop Text Demo
	14.15.11.	Using Actions with Text Components: JTextField
	14.15.12.	HighLight painter and JTextField
	14.15.13.	Limit JTextField input to a maximum length
	14.15.14.	Apply special filter to a JTextField
	14.15.15.	Format JTextField's text to uppercase
	14.15.16.	Add key listener event handler to JTextField
	14.15.17.	Right justified JTextfield content
	14.15.18.	Set the focus on a particular JTextField
	14.15.19.	Customizing a JTextField Look and Feel
	14.15.20.	Cut, paste, and copy in a JTextField
	14.15.21.	Aligning the Text in a JTextField Component
	14.15.22.	Based on JTextField content, enable or disable a JButton
	14.15.23.	Subclass InputVerfier
	14.15.24.	extends JTextField to create integer JTextField