public void confirmItem() { this.subtotal += item.getTotal(); String subtotalStr = formatter.format(this.subtotal); text_bookID.setText(""); text_quantity.setText(""); text_subtotal.setText(subtotalStr); confirmAlert(); order.addItem(item); this.totalQuantity += item.getQuantity(); changeItemNumber(); btn_confirm.setDisable(true); btn_view.setDisable(false); text_totalItems.setDisable(true); item = null; }