multithreading - Java Callable Pool thread do it all on this same time -

hi have probleme thread. want 1 method n thread , don't know how it. : have list of new objects : create class(1) implements interface callable use because callable thread don't return void. next have list of string(url) next create list of object class (1) . next create executor , want thread on list of obcject n-thread

public class utltoimageconverter implements callable<bufferedimage> {      private string url;     private static bufferedimage image;      public utltoimageconverter(string url) {         this.url = url;         getimgfrompath(url);     }      public string geturl() {         return url;     }      public void seturl(string url) {         this.url = url;     }      public bufferedimage getimage() {         return image;     }      public void setimage(bufferedimage image) {         utltoimageconverter.image = image;     }      public static bufferedimage getimgfrompath(string path){         if(testurlimage4.imgcache.get(path) != null){             return testurlimage4.imgcache.get(path);         }         else{             url url = null;             try {                 url = new url(path);             } catch (malformedurlexception e) {                 e.printstacktrace();             }             try {                 image = imageio.read(url);             } catch (ioexception e) {                 e.printstacktrace();             }             system.out.println(testurlimage4.imgcache.size());             testurlimage4.imgcache.put(path, image);             return image;         }     }      @override     public bufferedimage call() throws exception {         system.out.println("url  "  +url);         getimgfrompath(url);         system.out.println("url ok "  +url);         return image;     }  } 

next :

arraylist<utltoimageconverter> threadlist = new arraylist<>();              for(string url : urlpathlist){                 threadlist.add(new utltoimageconverter(url));             }             executorservice executor = executors.newfixedthreadpool(10);          try { //          executor.invokeall(threadlist, 1000l, timeunit.seconds);             executor.invokeall(threadlist); //          executor.invokeany(threadlist);         } catch (interruptedexception e1) {             e1.printstacktrace(); //      } catch (executionexception e) { //          e.printstacktrace();         }        

the problem call getimgfrompath() constructor of utltoimageconverter. so, images downloaded in process of instantiation, sequentially, before being submitted executor. executor retrieves them cache, don't see difference. remove getimgfrompath() call constructor , let executor actual downloading.