java - How to manipulate Object through the selectedItem of a Combobox -

just in case want me, appreciate lot that, because i'm noob in java , trying learn concept and, in same time, maintain code clean , read. if think it's stupid question because have wrong approach coding, care opinion , if explain me why try experience.

now questions is:

i have mainapp containing observablelist of persons , observablelist of events

public class mainapp extends application {    private stage primarystage;    private borderpane rootlayout;    private observablelist<evento> eventi = fxcollections.observablearraylist();    private observablelist<person> persons = fxcollections.observablearraylist();     public observablelist<evento> geteventi() {        return eventi;    }     public observablelist<person> getpersons() {        return persons;    }     public static void main(string[] args) {launch(args);}     public void start(stage primarystage){        this.primarystage = primarystage;        this.primarystage.settitle("bettator events");          person test = new person("daniele", "giaquinto");        test.geteventi().add(new evento("danevento", 1.0, "testconto"));        persons.add(test);        person test2 = new person("roberto", "sellitto");        test2.geteventi().add(new evento("robevento", 31.0, "testco"));        persons.add(test2);         initrootlayout();        showeventilayout(); } 

person object have list of events too, created after, because trying create responsive gui, in case, instead of 1 list of events, every single person have events list.

public class person {    private stringproperty firstname;    private stringproperty lastname;    private stringproperty nickname;    private observablelist<evento> eventi = fxcollections.observablearraylist(); 

i created eventylayout combobox , tableview, when change combobox, using listener, tableview populated events list of person object, did filling mainapp events list selected person events list

(eventicontroller)

public class eventilayoutcontroller { private mainapp mainapp;  @fxml private combobox<person> utentecmb; @fxml private tableview<evento> eventitbl; @fxml private tablecolumn<evento, string> eventocol; @fxml private tablecolumn<evento, double> importocol; @fxml private tablecolumn<evento, string> contocol;  @fxml void initialize() {      eventocol.setcellvaluefactory(celldata -> celldata.getvalue().nomeproperty());     importocol.setcellvaluefactory(celldata -> celldata.getvalue().importoproperty().asobject());     contocol.setcellvaluefactory(celldata -> celldata.getvalue().contoproperty());     utentecmb.setcellfactory((combobox) -> new listcell<person>() {         //cut stackoverflow     });     utentecmb.setconverter(new stringconverter<person>() {         //cut stackoverflow     });     utentecmb.getselectionmodel().selecteditemproperty().addlistener((observable, oldvalue, newvalue) -> {         mainapp.geteventi().clear();         mainapp.geteventi().addall(newvalue.geteventi());     }); }  public void setmainapp(mainapp mainapp){     this.mainapp = mainapp;      eventitbl.setitems(mainapp.geteventi());     utentecmb.setitems(mainapp.getpersons()); } 

}

before project without possibility switch user, , created "handleaddevent" add event mainapp list, in rootlayoutcontroller (the 1 show me menubar , menu item, add button is)

public class rootlayoutcontroller {  private mainapp mainapp;  @fxml // resourcebundle given fxmlloader private resourcebundle resources;  @fxml // url location of fxml file given fxmlloader private url location;  @fxml // method called fxmlloader when initialization complete void initialize() {  }  /**  * needed pass mainapp controller ad use public variable  */ public void setmainapp(mainapp mainapp){     this.mainapp = mainapp; }  /**  * open dialog add new event, add event collection  */ @fxml private void handleadd() {     evento evento = new evento();     boolean okclicked = mainapp.showeventiediteditdialog(evento);     if (okclicked)         mainapp.geteventi().add(evento); } } 

but tried go more deep learning, , need add event directly person->event, if try add using same function, add mainapp events list , not person events list, if mainapp persons list filled person events.

i wondering if there way pass pointer observablelist mainapp or there simple-way reach objective.

rootlayoutcontroller didn't know there combobox when try add event, , mainapp too, didn't have know there combobox, how selectedperson , add event events list?

should create "activeperson" mainapp , switch everytime user change item combobox? seem me , "hard coding" method.

how do?

well, there no 1 right way of designing app. of course there design principles, should try follow. there lot of information topic, won't problem find it.
specific case, move combobox , person selection logic eventilayoutcontroller rootlayoutcontroller. way have selected person instance in root controller , can notify event controller when change occurred , provide selected person it. notify can done either having eventilayoutcontroller instance directly in rootlayoutcontroller or using event bus approach example.
instead of mainapp.geteventi().addall(newvalue.geteventi()); i'd use property binding (or bidirectional binding, depending on logic). don't quite understand why need separate eventi collection in mainapp, if filling selected person events anyway.