dart - Sum of integer values of a Future -

i'm trying parse html document, image-sources , add size of pictures together. parsing document works fine, getting image-sources , getting size.

main(){   print("please input url");   var url = stdin.readlinesync();    getimageurls(url).then((list) {     list.foreach((imageurl) {       getimagesize(imageurl).then((r) {         print("$imageurl, size: $r bytes");       });     });   }); }  future<int> getimagesize(string url){   final completer = new completer();   new streamcontroller()..stream.listen((str) => completer.complete(imagesize(str)))..add(url);   return completer.future; }  imagesize(string url){   return http.get(url).then((response) => response.bodybytes.length); } 

i'm struggeling add size of each individual image 1 integer. figured this

main(){   int total = 0;   print("please input url");   var url = stdin.readlinesync();    getimageurls(url).then((list) {     list.foreach((imageurl) {       getimagesize(imageurl).then((r) {         print("$imageurl, size: $r bytes");         total += r;       });     });   });   print(total); } 

but i'd need wait getimageurls finish before im able print total.

can push me in right direction? feel i'm missing obvious.

the easiest way use "new" async/await

main() async {   int total = 0;   print("please input url");   var url = stdin.readlinesync();    var list = await getimageurls('url');   for(int = 0; < list.length; i++) {     var imageurl = list[i];     var r = await getimagesize(imageurl);     print("$imageurl, size: $r bytes");     total += r;   }   print(total); } 

or future.wait mentioned in comment

main(){   int total = 0;   print("please input url");   var url = stdin.readlinesync();    getimageurls(url).then((list) {     return future.wait(list.map((r) {       return getimagesize(imageurl).then((r) {         print("$imageurl, size: $r bytes");         total += r;       });     });   }).then((_) => print(total)); }