java - How to get data on a reference first before executing other code? -

i need data specific location on firebase , put data inside arraylist before processing it. have this:

final arraylist<string> data = new arraylist<string>(); firebase ref = rootref.child("data"); ref.addlistenerforsinglevalueevent(new valueeventlistener() {}     @override     public void ondatachange(datasnapshot snap) {         (object obj : snap.getchildren) {             data.add(obj.getvalue().tostring());         }     } ); processdata(data); 

i'm newbie kind of stuff, think not if there's tons of data read , if user's connectivity slow.

any idea on how solve problem?

i not familiar firebase shocked if did not have sort of equivalent android loader callback "onloadfinished(){...}". should find similar in firebase, , call "processdata(data)" within it.