Java Multi-Threading and Concurrency Library Advanced application-callable and future application

Callable such a task can return results, and the returned results can be taken from the future.

The result type obtained by >future and the result type returned by callable must be the same, which is achieved by generics.

>completionservice is used to submit a set of callable tasks whose take method returns the corresponding future object for a completed callable task.

　　Like I planted a few pieces of wheat at the same time, and then waited for the harvest. When the harvest is ripe, it is the first to reap the wheat.

  future<string> future = Threadpool.submit (new  callable< String> () {@Override  public String Call () throws   Exception {Threa                D.sleep ( 2000 return  "Hello" ;        }        });        SYSTEM.OUT.PRINTLN ( wait result  try   {System.out.println ( "Get results:        "+future.get ());  catch   (Exception e) {E.printstacktra        CE (); }

This type of hair is the future to actively ask callable whether it produces results

>completionservice is used to submit a set of callable tasks whose take method returns the corresponding future object for a completed callable task.

Executorservice executor = Executors.newfixedthreadpool (10); Completionservice<Integer> Completionservice =NewExecutorcompletionservice<>(executor);  for(inti = 0;i<10;i++){            Final intSeq =i; Completionservice.submit (NewCallable<integer>() {@Override PublicInteger Call ()throwsException {thread.sleep (NewRandom (). Nextint (5000)); returnseq;        }            }); }         for(inti = 0;i<10;i++) {//waiting to get results            Try{System.out.println (Completionservice.take (). get ()); } Catch(Exception e) {e.printstacktrace ();        }; }

Java Multi-Threading and Concurrency Library Advanced application-callable and future application