}
public void testAddObserver() {
NSNotificationCenter nc = NSNotificationCenter.defaultCenter();
TestObserver observer = new TestObserver();
nc.addObserver(observer, new NSSelector<Void>("invoked", new Class[] { NSNotification.class }), "test", null);
try {
nc.addObserver(observer, new NSSelector<Void>("invoked", new Class[] { Object.class }), "test", null);
fail("IllegalArgumentException expected");
} catch (IllegalArgumentException e) {
}