NumberAxis numberAxis = (NumberAxis) axis;
if (tickInterval > 0) {
NumberTickUnit tickUnit = new NumberTickUnit(tickInterval);
numberAxis.setTickUnit(tickUnit);
} else if (tickInterval == -1) {
TickUnitSource tickUnits = NumberAxis.createIntegerTickUnits();
numberAxis.setStandardTickUnits(tickUnits);
} else {
throw new FacesException("tickInterval must be a positive number for a fixed tick interval, " +
"or -1 for automatic integer tick selection: " + tickInterval);
}