线程池怎么将执行的结果全部返回

问题场景：
需要在线程池中的线程执行完后将数据全部返回，但是现在是返回了部分的数据，未将线程池中的线程的执行结果全部返回

     JSONObject res = new JSONObject(); //返回前台的数据
    long start = System.currentTimeMillis(); 
    log.info("======接入系統上報量線程執行開始=======");
    ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(   // 定义线程池
           3，
           5，
           2L,
           TimeUnit.SECONDS,
           new ArrayBlockingQueue<>(3),
           Executors.defaultThreadFactory(),
           new ThreadPoolExecutor.AbortPolicy()
    );

  try{
            statisticSystemNum.stream().forEach(t -> {
                      threadPoolExecutor.execute(() ->{
                        t.put("value",  tj07Mapper.countOneByOne(0,druidType,gc0100));// 查询数据库，并将数据设置到res中
                        log.info("執行了tttt====>" + t.get("value"));
            });
        });
    }catch (Exception e){
        e.printStackTrace();
    }finally {
        threadPoolExecutor.shutdown();
        long end = System.currentTimeMillis();
        log.info("======接入系統上報量線程執行結束=====共花費=="+(end-start)+"ms");
    }
     res.put("statisticSystemNum",statisticSystemNum);
      return res;
  }

使用ThreadGroup实现主线程等待所有子线程完成。

 
public class ThreadGroupDemo {
    public static void main(String[] args) {
        System.out.println("main start");
        ThreadGroup tg = new ThreadGroup("Parent ThreadGroup");
        for (int j = 0; j < 10; j++) {
            new Thread(tg, "t" + j) {
                public void run() {
                    System.out.println("Thread: " + getName() + " running");
                    int small = 0;
                    int large = 10;
                    try {
                        Thread.sleep(1000 * (int) (Math.random() * (large - small + 1) + small));
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }.start();
        }
        while (tg.activeCount() > 0) {
            try {
                System.out.println("Waiting for " + tg.activeCount() + " CThreads to Complete");
                Thread.sleep(1000); // Main Thread or someThradObject.sleep();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("main end");
    }
}