如果textfield包含数字，请检查运行时

Question

I am trying to figure out how i can check on runtime whether a number is being entered on a textfield and i want then to execute a Backspace to delete it on its own. My code is @FXML public void onKeyTyped(KeyEvent event) { if (!(event.getText().matches("[az]"))) { event.consume(); } } @FXML public void onKeyTyped(KeyEvent event) { if (!(event.getText().matches("[az]"))) { event.consume(); } }

I dont understand why it's not working. Maybe i dont understand the concept of changing something on runtime. Any input is greatly appreciated!

Answer 1

Im guessing its because you are checking az when you should be checking 0-9.

Edit: Oops, you're right I missed the !. As to it being runtime, aren't all events runtime?

Answer 2

you could try this (FX11 Only)

    //check if character typed is a number
    if (event.getCharacter().matches("[0-9]"))
    {
        event.consume();

        //move caret back one step as we do not want the typed digit
        //and want the caret to remain after last entered text
        textField.backward();

        //delete the typed digit
        textField.deleteNextChar();

    }

Note this uses event.getCharacter() instead of event.getText(). For me getText() is always empty,as in this link:

JavaFX KeyEvent.getText() returns empty?

Not also if you wish to go your original route of checking if it's not equal to az remember to account for AZ as well. Or convert the character to lower case before checking as matches is case specific.

FX8 Only

if (event.getCharacter().matches("[0-9]"))
    {
        event.consume();

    }