@Service
public class DataServiceImpl {
    /*@Autowired
    private EntityManagerFactory emf;*/

    @Autowired
    private EntityManager entityManager;

    public List<Object> showUser(int firstParam, int secondParam) {
        //EntityManager entityManager = emf.createEntityManager();
        String sql = "select * from sunny.user where id between ?1 and ?2";
        Query query = entityManager.createNativeQuery(sql);
        query.setParameter(1, firstParam);
        query.setParameter(2, secondParam);
        return query.getResultList();
    }
}

@Service
public class UserService {

    @Autowired
    private DataServiceImpl dataServiceImpl;

    public List<Object> callUser() throws InterruptedException, ExecutionException {
        int startParam = 1;
        int endParam = 6;
        List<Future<List<Object>>> futures = new ArrayList<>();
        ExecutorService executorService = Executors.newCachedThreadPool();
        List<Object> b = null;
        for (int i = startParam; i < 6; i++) {
            if (i == 1)
                endParam = startParam + 1;
            else {
                startParam += 1;
                endParam += 1;
            }
            Callable<List<Object>> callable = new ProcessingData(startParam, endParam);
            futures.add(executorService.submit(callable));
        }
        executorService.awaitTermination(40, TimeUnit.SECONDS);
        int i = 0;
        for (Future<List<Object>> f : futures) {
            if (i == 0) {
                b = new ArrayList<>(f.get());
            } else {
                b.add(f.get());
            }
            i++;
        }
        return b;
    }

    private class ProcessingData implements Callable<List<Object>> {
        private int firstParam;
        private int secondParam;
        /*
         * @Autowired private DataServiceImpl dataServiceImpl;
         */

        public ProcessingData(int firstParam, int secondParam) {
            super();
            this.firstParam = firstParam;
            this.secondParam = secondParam;
        }

        @Override
        public List<Object> call() throws Exception {
            return dataServiceImpl.showUser(firstParam, secondParam);
       }
    }
}

1  Iftekhar
2  Sunny
2018-05-27 13:29:19.096 ERROR 9836 --- [nio-8085-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.ClassCastException: java.util.ArrayList cannot be cast to [Ljava.lang.Object;] with root cause

java.lang.ClassCastException: java.util.ArrayList cannot be cast to [Ljava.lang.Object;
    at com.example.controller.UserController.showUser(UserController.java:24) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_144]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_144]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_144]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_144]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31]

Hibernate: select * from sunny.user where id between ? and ?
Hibernate: select * from sunny.user where id between ? and ?
Hibernate: select * from sunny.user where id between ? and ?
Hibernate: select * from sunny.user where id between ? and ?
Hibernate: select * from sunny.user where id between ? and ?

executorService.awaitTermination(40, TimeUnit.SECONDS);