Implementing alpha-numeric TextBox - gwt

Question

I am trying to implement a alpha-numeric textbox with this code:
textBoxNewPassword.addKeyPressHandler(new KeyPressHandler() {
#Override
public void onKeyPress(KeyPressEvent event) {
char keyCode = event.getCharCode();
TextBox sender = (TextBox) event.getSource();
if (!Character.isLetterOrDigit(keyCode)
|| !(keyCode == KeyCodes.KEY_TAB)
|| !(keyCode == KeyCodes.KEY_BACKSPACE)
|| !(keyCode == KeyCodes.KEY_LEFT)
|| !(keyCode == KeyCodes.KEY_RIGHT)
)
sender.cancelKey();
}
});
It works however, Backspace and Tab wont work, which is needed to erase something that user has type and to jump to another form fields.
Any ideas what's missing in this code?

Answer 1

tb.addKeyPressHandler(new KeyPressHandler() {
#Override
public void onKeyPress(KeyPressEvent event) {
TextBox sender = (TextBox) event.getSource();
int keyCode = event.getNativeEvent().getKeyCode();
if (!(Character.isLetterOrDigit(event.getCharCode()))
&& !(keyCode == KeyCodes.KEY_TAB)
&& !(keyCode == KeyCodes.KEY_BACKSPACE)
&& !(keyCode == KeyCodes.KEY_LEFT)
&& !(keyCode == KeyCodes.KEY_RIGHT)) {
sender.cancelKey();
}
}
});
This looks like it works.

Answer 2

I think the problem is with your conditions. Think about it like this: if the user hits Tab, then it won't be a letter or digit, so it cancels the key. You'd like to cancel only if it isn't any of the keys you would like, not if it isn't all of the keys (at once). If you change then to && instead it should work.
if (!Character.isLetterOrDigit(keyCode)
&& !(keyCode == KeyCodes.KEY_TAB)
&& !(keyCode == KeyCodes.KEY_BACKSPACE)
&& !(keyCode == KeyCodes.KEY_LEFT)
&& !(keyCode == KeyCodes.KEY_RIGHT)
)
sender.cancelKey();
If it isn't a letter or digit, and if it isn't a tab, and if it isn't a backspace, and not a left, and not a right, then cancel.

Answer 3

DTing is on the right track, but you can't be sure that you get the correct keycode (browser dependent) in the KeyPressEvent, you should use it in combination with a KeyDown handler. Especially things like backspace and delete is handled differently.
Source: http://code.google.com/p/google-web-toolkit/issues/detail?id=4212 and http://www.quirksmode.org/js/keys.html