public void addChild(PlantNode child) {
Set<PlantNode> gen = children.get(child.getGeneration());
if (gen == null) {
// create new generation
gen = new HashSet<>();
gen.add(child);
children.put(child.getGeneration(), gen);
} else {
// add to existing generation
gen.add(child);
}
}
public void removeChild(PlantNode child) {
Set<PlantNode> gen = children.get(child.getGeneration());
if (gen != null) {
gen.remove(child);
}
}