this.procedure = procedure;
parameter.first.addListener(graph, parameter.second, this);
}
-
+
@Override
public void unregistered() {
- parameter.first.removeListener(session, parameter.second, this);
+ // Session will be null if the listener was not added at all.
+ if (session != null) {
+ parameter.first.removeListener(session, parameter.second, this);
+ }
}
-
+
@Override
public void run() {
synchronized(getClass()) {
procedure.execute(value++);
}
}
-
+
}
\ No newline at end of file