java - How to ensure execution order -

what different ways , best way ensure order of execution when different database operations involved , 1 operations depends on other operations. in code this:

string countryname = "name"; country countryobj = new country(); countryobj.setname(countryname); countryobj.setstates(new arraylist<state>()); // update database persistencemanager manager = new persistencemanager(); list<country> countries = manager.getallcountries();                     if (countries != null && !countries.isempty()) {     (country country2 : countries) {         if (country2.getname().equalsignorecase(countryname)) {             return;         }     } } manager.savecountry(countryobj, country); 

here manager.getallcountries() retrieves countries database , manager.savecountry depends on previous operation

i think need start point of looking @ modeling data use atomic operations.

what describing insert data if not present. upsert , looking logic if country exists don't want change (as return out of method). can use $setoninsert operator - only save values of countryobj if doesn't exist.

the last hurdle name matching - testing equivalence against lowercased versions of names - use regular expression in query full scan of documents in collection - alternative store lowercased name match against.

an example queries , inserts if not present using shell syntax below:

db.collection.update(    {lname: countryname.tolowercase()},    { $setoninsert: { name: countryname, states: [{name: "victoria"}]  } },    { upsert: true } ) 

of course if wanted update information if country exist can use $set operator update if country exists.