java - FutureTask call() refer object, result wrong -


i want result 

jsonobject={"key":[2,2,3]} jsonobject={"key":[2,4,3]} jsonobject={"key":[2,4,6]}

but result is

{"key":[2,4,6]} {"key":[2,4,6]} {"key":[2,4,6]}

i dont know what's wrong. please help. thanks!

how change code? object last number.

code is:

public class testfuturetask {     public static void main(string[] args) {         int[] list = {1,2,3};         executorservice executor = executors.newcachedthreadpool();         list<futuretask<string>> futuretasks = new arraylist<>();          for(int i=0;i<list.length;i++){             int[] list1 = list;             list1[i] = list1[i]*2;             jsonobject jsonobject = new jsonobject();             jsonobject.put("key", list1);             futuretasks.add(new futuretask<string>(new queryexecutor(jsonobject)));         }          for(int n=0;n<futuretasks.size();n++){             executor.submit(futuretasks.get(n));         }          for(int n=0;n<futuretasks.size();n++){             try {                 system.out.println(futuretasks.get(n).get());             } catch (interruptedexception e) {                 e.printstacktrace();             } catch (executionexception e) {                 e.printstacktrace();             }             {                 executor.shutdown();             }         }     } }  class queryexecutor implements callable<string> {     private jsonobject jsonobject;     public queryexecutor(jsonobject jsonobject){         system.out.println("jsonobject="+jsonobject);         this.jsonobject = jsonobject;     }     @override     public string call(){         string result = jsonobject.tostring();         return result;     }  }

i think maybe async , method call() refer object problem.

executorservice , futuretask.

as reminder arrays in java objects.

your problem same object referencing see below snippet of code

 int[] list = {1,2,3};  int[] list1 = list;  list1[i] = list1[i]*2;

when update reference list1 list gets updated because point same object internally , hence array passed below call method in furture reference same.

try changing from

int[] list1 = list;

to 

int[] list1 = arrays.copyof(list,list.length);

run , see if meets expectations


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