How to prevent input of letters and use of a space in Java?

Closed due to the fact that the essence of the question is unclear by the participants of pavel , Nofate ♦ 1 Sep '16 at 17:04 .

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    Where exactly? Which UI? - Chubatiy

1 answer 1

You can use the ban on letters and space, the user can enter only numbers:

JTextField textField = new JTextField(10); textField.addKeyListener(new KeyAdapter() { public void keyTyped(KeyEvent e) { char c = e.getKeyChar(); if ( ((c < '0') || (c > '9'))) { e.consume(); // игнорим введенные буквы и пробел } } });

If you need any characters, you can find their code on the Oracle page and add it to the if :

 if ( ((c < '0') || (c > '9')) && (c != KeyEvent.VK_PLUS)) { e.consume(); // разрешаем цифры и знак "+" }
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    And why did you decide that the author is not a regular console application? - Alexey Shimansky