在碰到此链接http://www.javacodegeeks.com/2013/01/java-thread-pool-example-using-
executors-and-threadpoolexecutor之后，这是我第一次为新项目使用Java线程池。
.html，我对此更加困惑，这是页面中的代码，

package com.journaldev.threadpool;

public class WorkerThread implements Runnable {

    private String command;

    public WorkerThread(String s){
        this.command=s;
    }

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName()+' Start. Command = '+command);
        processCommand();
        System.out.println(Thread.currentThread().getName()+' End.');
    }

    private void processCommand() {
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    @Override
    public String toString(){
        return this.command;
    }
}


package com.journaldev.threadpool;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class SimpleThreadPool {

    public static void main(String[] args) {
        ExecutorService executor = Executors.newFixedThreadPool(5);
        for (int i = 0; i < 10; i++) {
            Runnable worker = new WorkerThread('' + i);
            executor.execute(worker);
          }
        executor.shutdown();
        while (!executor.isTerminated()) {
        }
        System.out.println('Finished all threads');
    }

}

在代码中，创建了一个固定大小的池并创建了10个工作线程，对吗？

线程池应该减轻系统的负担，相反，在上面的代码中，我认为通过在工作线程之外创建池来增加负担。为什么要麻烦使用线程池？

谁能解释？谢谢