ConcurrentModificationException in NotificationCenter.publish

[mgznt]

When trying to subscribe to events during a call to NotificationCenter.publish(), you get a ConcurrentModificationException from the subscribers list.

One solution would be to make a copy of the subscribers list before publishing. Here's a minimal test case (tested with mvvmFx 1.3.1):

import org.junit.Test;

import de.saxsys.mvvmfx.utils.notifications.NotificationCenter;
import de.saxsys.mvvmfx.utils.notifications.NotificationCenterFactory;

public class NotificationCenterTest {
  @Test
  public void shouldAllowSubscribeDuringPublish() throws Exception {
    NotificationCenter c = NotificationCenterFactory.getNotificationCenter();

    /* Minimal example (triggers a ConcurrentModificationException in NotificationCenter */
    c.subscribe("MSG", (key1, payload1) -> {
      c.subscribe("MSG", (key2, payload2) -> {
        System.out.println("I want to subscribe during a publish()");
      });
    });

    c.publish("MSG");

    /*
     * Real use case:
     * 
     *      ParentView
     *       |       |
     * ChildView1  ChildView2
     * 
     *  
     * ChildView1 publishes a global event that causes ParentView
     * to create a new instance of ChildView2.
     * ChildView2 tries to subscribe to another global event in its initialize() method.
     * 
     * Because NotificationCenter.publish() does not make a copy before publishing
     * events, we get a ConcurrentModificationException. 
     */
  }
}

[manuel-mauky]

Thanks for your report. I've created a PR (#290) that fixes the problem and makes your test case green.
You can test it with the 1.4.0-SNAPSHOT.

[mgznt]

Wow, that was quick! Thanks 👍