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Graphics, AWT, Swing II part<br />
else<br />
return false;<br />
Or<br />
you can test whether text = = null,<br />
then check if myJTextField.getText().length() == 0<br />
if it is not, do text=text.trim() to remove spaces,<br />
then check text.equals("") to see if it is an empty String<br />
--<br />
Lucio Benfante, Arnaud Berger and Jorge Jordao<br />
Q: Whats the difference between a Frame and a canvas? Can someone tell me<br />
the difference?<br />
Answer:<br />
A Frame is , well , a frame - a window, with borders,close/minimize/maximize buttons<br />
(usually), and can not contain other elements, such as a menubar ,buttons panels,<br />
etc.<br />
a Canvas is a user interface element (which you can place in e.g. a frame) onto<br />
which you can draw/display something..<br />
-by<br />
Nils O. Selåsdal<br />
Q: I know how to make a text box using Visual Basic that can only accept certain<br />
keys for example if I wanted to make a box where you can type only numbers in it or<br />
letters. However, when it comes to <strong>Java</strong> I have not been able to figure this out. Is<br />
there a way to do this and make a textbox where you can only type letters in it?<br />
Answer: First of all, 'ASCII' is not a synonym for 'text'. ASCII is just one of many ways<br />
of encoding text to numeric values. It is 7-bit and only includes values from 0 through<br />
127.<br />
Now, on to your question. With ASCII, 'numbers' and 'letters' are a little easier to<br />
check, since the only letters are 'A'-'Z' and 'a'-'z'. However, <strong>Java</strong> uses Unicode and<br />
has all sorts of fun extra characters.<br />
But you do have a few handy methods on the java.lang.Character class such as<br />
isDigit and isLetter<br />
Now, if you are using swing, then to achieve what I'm guessing you want is quite<br />
simple. Just hook a custom text document to the JTextField you're using and have it<br />
do the filtering.<br />
** Here's the part of The <strong>Java</strong> Tutorial that goes over it<br />
http://java.sun.com/docs/books/tutorial/uiswing/components/textfield.html#validation<br />
Here's someone's Swing FAQ on that<br />
http://users.vnet.net/wwake/swing/faq.html#text_check<br />
Here's a <strong>Java</strong>World article that describes how to do that to limit the length of input.<br />
Shouldn't be too hard for you to change to your specific needs.<br />
http://www.javaworld.com/javaworld/javaqa/2000-05/02-qa-0512-textbox_p.html<br />
All these links were from the first page of a search on http://www.google.com<br />
Google is your friend!<br />
file:///F|/350_t/350_tips/graphics-II.htm (4 of 6) [2002-02-27 21:18:10]
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