在示例代码中说明回电

Question

我遵循了教程（here）

但是我不明白。据我所知，回调是将在主线程完成后调用的东西。我尝试运行该示例，但这不是我所理解的。

这些是我的课程：

InterestingEvent.java

package callback;

public interface InterestingEvent {
     // This is just a regular method so it can return something or
    // take arguments if you like.
    public void interestingEvent ();
}

CallMe.java

package callback;

public class CallMe implements InterestingEvent {

    private EventNotifier en; 
    public CallMe ()
    {
    // Create the event notifier and pass ourself to it.
    en = new EventNotifier (this);
    } 
    // Define the actual handler for the event.
    public void interestingEvent ()
    {
    // Wow!  Something really interesting must have occurred!
    // Do something...
        System.out.println("Interesting event method");
    } 


}

EventNotifier.java

package callback;

public class EventNotifier {
    private InterestingEvent ie;
    private boolean somethingHappened; 
    public EventNotifier (InterestingEvent event)
    {
    // Save the event object for later use.
    ie = event; 
    // Nothing to report yet.
    somethingHappened = true;
    } 
    public void doWork ()
    {
        System.out.println("doWork 1");
    // Check the predicate, which is set elsewhere.
    if (somethingHappened)
        {
        System.out.println("doWork 2");

        // Signal the even by invoking the interface's method.
        ie.interestingEvent ();
        System.out.println("doWork 3");
        }
    } 

    public static void main(String[] args) {
        InterestingEvent ie = new CallMe();
        EventNotifier e = new EventNotifier(ie);
        e.doWork();
        System.out.println("Main flow finish!");
    }
}

输出：

doWork 1
doWork 2
Interesting event method
doWork 3
Main flow finish!

主线程在程序结尾处完成。

据我所知，输出应为：

Main flow finish! -- Main thread should be done first!!!
doWork 1
doWork 2
Interesting event method
doWork 3

请任何人解释该示例，什么不正确？

谢谢！