java - Right way to implement encapsulation -

i have following class scheme.

national have arraylist of zone, zone arraylist of region , region have arraylist of person.

so have next questions:

1) can "push" person trough national , zone add in region?

for example:

national national = new national(); .... national.addperson(person); // every level has own addperson method 

or

national.getzone(i).getregion(i).addperson(person); 

what right way in oop?

2) can make method return every person in level?

i mean example:

zone zone = new zone(); ... zone.getpersons(); //return arraylist persons of every region in zone. 

this goes against encapsulation?

3) next(), hasnext(), first() methods every level, can iterate in particular level.

that's all. encapsulation , oop in general, can't figure out right do, , wrong.

thanks.

given class diagram, person must member of region, is, national or zone cannot directly contain person objects not contained in region under it.

in case method matching signature addperson(person p) can occur in region. indicated, have do

national.getzone(i).getregion(j).addperson(person); 

there no logical reason have, say,

national#addperson(person p) 

because national has no information on zone , region person belongs to.

however, add convenience methods national , zone to, call it, "push" person down, if provide necessary data.

national#addperson(zoneid zid, regionid rid, person) { ... 

for zoneid , regionid substitute whatever key type use lookup zone , region within national.

zone#addperson(regionid rid, person) { ... 

as above regionid.

this start, you'll have think through issues such happens when zoneid and/or regionid not found on addperson(...) call. in design viable option throwing exception because don't have enough information @ point instantiate zone or region.

edit:

if indicated in comment, person object contains enough information identify zone , region, convenience methods in national , zone can required lookup , delegate next addperson(person p) in chain.