等待Executor中的所有线程完成？

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

public class WaitForExecutor {
    public static void main(String[] args) {
        ExecutorService executor = Executors.newFixedThreadPool(5);

        for (int i = 0; i < 10; i++) {
            Runnable task = new Task();
            executor.execute(task);
        }

        executor.shutdown();

        try {
            executor.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("All tasks have been completed.");
    }
}

class Task implements Runnable {
    @Override
    public void run() {
        // do something
    }
}