DocumentFilter는 어떻게 JTextField 입력을 정수로 효과적으로 제한할 수 있습니까?

class MyIntFilter extends DocumentFilter {
    @Override
    public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) 
        throws BadLocationException {

        Document doc = fb.getDocument();
        StringBuilder sb = new StringBuilder();
        sb.append(doc.getText(0, doc.getLength()));
        sb.insert(offset, string);

        if (test(sb.toString())) {
            super.insertString(fb, offset, string, attr);
        } else {
            // warn the user and don't allow the insert
        }
    }

    private boolean test(String text) {
        try {
            Integer.parseInt(text);
            return true;
        } catch (NumberFormatException e) {
            return false;
        }
    }

    ... // Other overridden methods for replace and remove
}