/*

 * Cay S. Horstmann & Gary Cornell, Core Java

 * Published By Sun Microsystems Press/Prentice-Hall

 * Copyright (C) 1997 Sun Microsystems Inc.

 * All Rights Reserved.

 *

 * Permission to use, copy, modify, and distribute this 

 * software and its documentation for NON-COMMERCIAL purposes

 * and without fee is hereby granted provided that this 

 * copyright notice appears in all copies. 

 * 

 * THE AUTHORS AND PUBLISHER MAKE NO REPRESENTATIONS OR 

 * WARRANTIES ABOUT THE SUITABILITY OF THE SOFTWARE, EITHER 

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE 

 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 

 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. THE AUTHORS

 * AND PUBLISHER SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED 

 * BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING 

 * THIS SOFTWARE OR ITS DERIVATIVES.

 */

 

/**

 * A text field that accepts only integers

 * @version 1.1 27 Mar 1997

 * @author Cay Horstmann

 */



package corejava;



import java.awt.*;

import java.awt.event.*;



public class IntTextField extends TextField 

   implements TextListener

{ /**

   * Creates the text field

   * @param defval an integer default,

   * @param size the size of the text field

   */

   public IntTextField(int defval, int size)

   {  super("" + defval, size);

      addTextListener(this);

      addKeyListener(new KeyAdapter() 

         {  public void keyTyped(KeyEvent evt)

            {  char ch = evt.getKeyChar();

               if (!('0' <= ch && ch <= '9' 

                     || ch == '-'

                     || Character.isISOControl(ch)))

                  evt.consume();

               else

                  lastCaretPosition = getCaretPosition();

            }

         });

      lastValue = "" + defval;

   }



   public void textValueChanged(TextEvent evt)

   {  checkValue();  

   }



   private void checkValue()

   {  try

      {  Integer.parseInt(getText().trim() + "0");

         lastValue = getText();

      }

      catch(NumberFormatException e)

      {  setText(lastValue);

         setCaretPosition(lastCaretPosition);

      }

   }



   /**

   * Get the integer data value

   * @return the integer data value

   * @remark if invalid, returns the valid prefix (or 0 if none)

   * This only happens when the field is blank or contains just a 

   * single -

   */



   public int getValue()

   {  checkValue();

      try

      {  return Integer.parseInt(getText().trim());

      }

      catch(NumberFormatException e)

      {  return 0; 

      }

   }



   private String lastValue;

   private int lastCaretPosition;

}