public void updatePageCounterField(int n) { if (pageCounterField == null) return; if (n == 0) { pageCounterField.setBackground(pageCounterFieldDefaultColor); pageCounterField.setForeground(Color.BLACK); pageCounterButton.setForeground(pageCounterButtonDefaultForeground); } else { pageCounterField.setBackground(pageCounterFieldColor); pageCounterField.setForeground(Color.WHITE); pageCounterButton.setForeground(pageCounterFieldColor); } pageCounterField.setText("" + n); }