rx java - RxJava Solution to prevent blocking in multithread environment -

the task:

i have set of unique values - ["a","b","c","d"] multiple threads trying remove values it. when becomes empty code should notify listeners.

in java need block threads each time remove element , check if collection empty prevent sending 2 same events @ time.

so can implement somehow rxjava without blocking execution?

p.s. in real program there many of sets.

your question bit vague sounds you'd want this:

final class rxset {     final set<string> elements = new hashset<string>();      final asyncsubject<object> onempty = asyncsubject.create();      public rxset(string... initialvalues) {          elements.addall(arrays.aslist(initialvalues));     }      public observable<object> onempty() {          return onempty;     }      public boolean take(string item) {         boolean wasempty = false;         boolean isempty = false;         boolean success = false;          synchronized (this) {             wasempty = set.isempty();             success = set.remove(item);             isempty = set.isempty();         }          if (!wasempty && isempty) {             onempty.onnext("became empty");             onempty.oncomplete();         }          return success;     } }