问如何确保线程被完全执行？(使用线程池)

EN

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

public class ClassMain
{
    public static void main(String[] args)
    {
        ExecutorService executor = Executors.newFixedThreadPool(3);

        for (int i = 1; i <= 200 ;i++) {
            Runnable coordinator = new Coordinator(i);
            executor.execute(coordinator);
        }

        executor.shutdown();

        while (!executor.isTerminated());

        Coordinator.print();
    }
}

import java.util.ArrayList;

public class Coordinator implements Runnable
{
    public static ArrayList<Integer> javaStudents;

    private int studentNumber;

    public Coordinator(int studentNum)
    {
        studentNumber = studentNum;
        javaStudents = new ArrayList<Integer>();
    }

    public static synchronized void processCommand(int studentNumber)
    {
        javaStudents.add(studentNumber);
    }

    @Override
    public void run()
    {
        System.out.println(Thread.currentThread().getName() + " Starting to add student# " + studentNumber + " to Java");
        processCommand(studentNumber);
        System.out.println(Thread.currentThread().getName() +" Ended adding student#" + studentNumber + " to Java");
    }

    public static void print()
    {
        for (int i = 0; i < javaStudents.size(); i++) {
            System.out.println("Student #" +javaStudents.get(i) + " enrolled to Java");
        }
        System.out.println("Array size: " + javaStudents.size());
    }
}