rx java - RxJava - Just vs From -

i'm getting same output when using observable.just vs observable.from in following case:

 public void myfunc() { //swap out here , same results,why ?         observable.just(1,2,3).subscribe(new subscriber<integer>() {             @override             public void oncompleted() {                 log.d("","all done. oncompleted called");             }              @override             public void onerror(throwable e) {              }              @override             public void onnext(integer integer) {                 log.d("","here integer:"+integer.intvalue());             }         });      } 

i thought 'just' suppose emit single item , 'from' emit items in sort of list. whats difference ? noted 'just' , 'from' takes limited amount of arguments. observable.just(1,2,3,4,5,6,7,8,-1,-2) ok observable.just(1,2,3,4,5,6,7,8,-1,-2,-3) fails. same goes from, have wrap in list or array of sorts. i'm curious why cant define unlimited arguments.

update: experimented , saw 'just' not take array structure 'just' takes arguments. 'from' takes collection. following works 'from' not 'just':

 public observable myfunc() {      integer[] myints = {1,2,3,4,5,6,7,8,-1,-2,9,10,11,12,13,14,15};    return  observable.just(myints).flatmap(new func1<integer, observable<boolean>>() {         @override         public observable<boolean> call(final integer integer) {             return observable.create(new observable.onsubscribe<boolean>() {                 @override                 public void call(subscriber<? super boolean> subscriber) {                     if(integer.intvalue()>2){                         subscriber.onnext(integer.intvalue()>2);                      }                 }             });         }     });  } 

i assuming clear difference then, correct ?

the difference should clearer when @ behaviour of each when pass iterable (for example list):

observable.just(somelist) give 1 emission - list.

observable.from(somelist) give n emissions - each item in list.

the ability pass multiple values just convenience feature; following functionally same:

observable.just(1, 2, 3); observable.from(1, 2, 3);