Thread: Restrict String character's type and location.

I have the next dialog to pop up and ask the user for some info:

String id = (String)JOptionPane.showInputDialog(
						null,
						"Post #",
						"Información del cliente.",
						JOptionPane.PLAIN_MESSAGE
						);

The format I would like it to be like one of this:

1. Only numbers.
or
2. Limit the first character to a "+" and the rest numbers.
or
3. Limit the first character to a "." and the rest numbers.

So, I hope you guys understand what I want.

I don't want to get the string and subtract the characters that I want, I want to limit the characters that the user can type in the dialog box.

Thanks.

Okay, I updated my code to this:

JPanel userPanel = new JPanel();
				userPanel.setLayout(new GridLayout(2,1));
 
				JLabel posLbl = new JLabel("POS #:");
				posLbl.setFont(font2);
				JTextField posFld = new JTextField();
				posFld.setFont(font);
 
				userPanel.add(posLbl);
				userPanel.add(posFld);
 
				int input = JOptionPane.showConfirmDialog(userPanel, userPanel, "Información del cliente."
						,JOptionPane.OK_CANCEL_OPTION, JOptionPane.PLAIN_MESSAGE);
 
				if (input == 0)
				{
					String id = posFld.getText();
}

How would I do it with a JTextField class?

I've been reading about it for the past 45 minutes and I still have no Idea how they limit the characters:

For example, i found the next code:

class DocumentInputFilter extends DocumentFilter
	{
		public void replace(FilterBypass fb, int offset
				, int length, String text, AttributeSet as) throws BadLocationException
				{
			int len = text.length();
			if (len > 0)
			{
				if (Character.isDigit(text.charAt(len - 1)))
					super.replace(fb, offset, length, text, as);
				else 
				{
					JOptionPane.showMessageDialog(null, "Please Enter a valid Integer Value."
							, "Invalid Input : ", JOptionPane.ERROR_MESSAGE);
					Toolkit.getDefaultToolkit().beep();
				}
			}                                               
				}

It will get the numbers part done, but how do I add the "." and the "+" to the exceptions?