android - RxJava - Consuming a GroupedObservable -

given following code:

bcxclient   .fetchtodos()   .flatmap(new func1<list<bcxtodo>, observable<bcxtodo>>() {     @override     public observable<bcxtodo> call(list<bcxtodo> bcxtodos) {       return observable.from(bcxtodos);     }   })   .groupby(new func1<bcxtodo, bcxtodolist>() {     @override     public bcxtodolist call(bcxtodo bcxtodo) {       return bcxtodo.todolist;     }   })   .tolist(); 

which returns list<groupedobservable<>>. in code, need count how many objects there in each groupedobservable. if use count() function returns observable<int>. following code won't work:

@override public int getchildrencount(int groupposition) {     int count;      mtodolist.get(groupposition)         .count()         .subscribe( new action1<integer>() {             @override             public void call(integer integer) {                 count = integer;             }         });      return count; } 

if make local variable final, can't assign value it.

so far can tell, have 2 options. store count each grouping in field belongs class, or transform groupedobservable alternate structure in chain (above). if case, what's best way this?

this code wrote translate groupedobservable:

.flatmap( new func1<groupedobservable<bcxtodolist, bcxtodo>, observable<bcxtodolist>>() {   @override   public observable<bcxtodolist> call(final groupedobservable<bcxtodolist, bcxtodo> bcxtodolistbcxtodogroupedobservable) {     return bcxtodolistbcxtodogroupedobservable       .tolist()       .flatmap( new func1<list<bcxtodo>, observable<bcxtodolist>>() {         @override         public observable<bcxtodolist> call(list<bcxtodo> bcxtodos) {           bcxtodolistbcxtodogroupedobservable.getkey().todos.addall( bcxtodos );            return observable.just( bcxtodolistbcxtodogroupedobservable.getkey() );         }       });   } }) 

i'm not sure if best way it

your first attemp doesn't work, count primitive value , not object.

to count, can block , value. (but current thread block)

@override public int getchildrencount(int groupposition) {     int count = mtodolist.get(groupposition).toblocking().single();     return count; } 

if don't want block, using pair alike structure seems idea

 bcxclient    .fetchtodos()    .flatmap(observable::from)    .groupby(bcxtodo-> bcxtodo.todolist)    .flatmap(todo -> todo.count().map(c -> new pair(todo, c))    .tolist()    .subscribe(pair -> //** iter on list **//);