import javax.swing.*;
import javax.swing.text.*;
import java.awt.Toolkit;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Locale;
/**
 * A subclass of PlainDocument which is used to restrict user input to whole numbers.
 * 
 * @author Michael Pell, Solutions Plus, Inc.
 */

public class WholeNumberField extends JTextField
{
	private Toolkit toolkit;
	private NumberFormat integerFormatter;
	protected class WholeNumberDocument extends PlainDocument
	{
		public void insertString(int offs, String str, AttributeSet a) throws BadLocationException
		{
			char[] source = str.toCharArray();
			char[] result = new char[source.length];
			int j = 0;
			for (int i = 0; i < result.length; i++)
			{
				if (Character.isDigit(source[i]))
					result[j++] = source[i];
				else
				{
					toolkit.beep();
					System.err.println("insertString: " + source[i]);
				}
			}
			super.insertString(offs, new String(result, 0, j), a);
		}
	}
public WholeNumberField(int value, int columns)
{
	super(columns);
	toolkit = Toolkit.getDefaultToolkit();
	integerFormatter = NumberFormat.getNumberInstance(Locale.US);
	integerFormatter.setParseIntegerOnly(true);
	setValue(value);
}
	protected Document createDefaultModel() {
		return new WholeNumberDocument();
	}
public int getValue()
{
	int retVal = 0;
	try
	{
		retVal = integerFormatter.parse(getText()).intValue();
	}
	catch (ParseException e)
	{
		// This should never happen because insertString allows
		// only properly formatted data to get in the field.
		toolkit.beep();
	}
	return retVal;
}
public void setValue(int value)
{
	setText(integerFormatter.format(value));
}
}