package com.test;

import java.util.concurrent.Callable;

public class TestThread implements Callable<Object>{

    @Override

    public Object call() throws Exception {

        System.out.println(123);

        return 456;

    }

}

package com.test;

import java.util.ArrayList;

import java.util.Collection;

import java.util.List;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

public class TestPool {

    public void handleThreadPool(){

        int threadCount = 5;

        int poolSize = 3;

        TestThread[] tt = new TestThread[threadCount];

        ExecutorService service = Executors.newFixedThreadPool(poolSize);

        Collection<TestThread> c = new ArrayList<TestThread>();

        for (int i = 0; i < threadCount; i++) {

            tt[i] = new TestThread();

            c.add(tt[i]);

        }

        try {

            List<Future<Object>> results = service.invokeAll(c);

            service.shutdown();

            for (Future<Object> future : results) {

                 System.out.println(future.get().toString());

            }

        } catch (InterruptedException e) {

            e.printStackTrace();

        } catch (ExecutionException e) {

            e.printStackTrace();

        }

    }

    public static void main(String[] args){

        TestPool tp = new TestPool();

        tp.handleThreadPool();

    }

}