java - How to execute this paralell task in Java8 -

i'm new in java concurrency, ask best way perform action this:

i have static method matches sub image within image. looks that:

public static point match(final bufferedimage subimage, final bufferedimage image) 

the method returns null if nothing matched, else returns point of match.

now have 40 different sub images 1 (big) image, want match in parallel. each second new (big) image in need search 40 smaller images on , on again. need return values of each call to match method @ end of match task in main task, can analyze it. furthermore need use many cpu cores possible task.

how can accomplish that? have read lot executorservice, task, runnable , on. examples show how print on console in paralles. confused way should go in scenario: how pass values , how results? how should layout of class(es) like? have no idea way go if create 40 tasks second (it take time setup task, right?)

code great explain :)

use completionservice, more executorcompletionservice.

class matcher {   executorservice threadpool = executors.newcachedthreadpool();   private list<bufferedimage> subimages; // populate   public static point match(bufferedimage subimage, bufferedimage image) {     // implementation   }   public list<point> match(bufferedimage image) {     completionservice<point> completionservice = new executorcompletionservice(threadpool);     int size = subimages.size();     list<point> results = new arraylist<>(size);     (bufferedimage subimage: subimages) {       completionservice.submit(()->match(subimage, image));     }     (int = 0; < size; i++) {       point point = completionservice.take().get();       if (point != null) {         results.add(point);       }     }     return results;   } } 

if want use cpu, want change executorservice executors.newworkstealingpool(). careful though!