How to remove a collect into a new stream from the middle of a java 8 stream? -

i'm working on java 8 stream. , need group 2 keys in map. , put these keys value new function.

is there way skip collector , reading out again?

graphs.stream()     .map(abstractbasegraph::edgeset)     .flatmap(collection::stream)     .collect(collectors.groupingby(         graph::getedgesource,         collectors.groupingby(             graph::getedgetarget,             collectors.counting()         )     ))     .entryset().stream()     .foreach(startentry ->         startentry.getvalue().entryset().stream()             .foreach(endentry ->                 graph.setedgeweight(                     graph.addedge(startentry.getkey(), endentry.getkey()),                     endentry.getvalue() / strains                 ))); 

no, have have sort of intermediate data structure accumulate counts. depending on how graph , edge classes written, try accumulate counts directly graph, less readable , more brittle.

note can iterate on intermediate map more concisely using map#foreach:

.foreach((source, targettocount) ->      targettocount.foreach((target, count) ->          graph.setedgeweight(graph.addedge(source, target), count/strains)     ) ); 

you can collect counts map<list<node>, long> instead of map<node,map<node,long>> if dislike map-of-maps approach:

graphs.stream()     .map(abstractbasegraph::edgeset)     .flatmap(collection::stream)     .collect(groupingby(             edge -> arrays.aslist(                 graph.getedgesource(edge),                  graph.getedgetarget(edge)             ),             counting()     ))     .foreach((nodes, count) ->          graph.setedgeweight(graph.addedge(nodes.get(0), nodes.get(1)), count/strains)     );