All Questions
7 questions
3votes
1answer
678views
Is Content Observer an implementation of Observer Pattern?
Observer Pattern is defined by the 'Gang of Four' Design Patterns book as a "one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated ...
10votes
2answers
3kviews
Is the observer pattern suitable when the observers are not independent of each other?
I have a class Car which has 2 properties: int price and boolean inStock. It also holds a List of abstract class State (empty class). There are 2 states which can be applied on the car and each is ...
- 272
2votes
2answers
2kviews
What preconditions should be checked while adding/removing a listener?
Imagine the following interface: interface Service { addListener(Listener l) removeListener(Listener l) } Should I check for null values while add/remove? Is it a good idea on remove to check ...
- 175
4votes
1answer
1kviews
I'm always reimplementing observer/subject code in Java. Is there a better option?
I'm always writing observer/subject interfaces in a particular Java project, e.g.: /** * Registers the receiver to the dispatcher. * When data arrives that the receiver can process, * it will be ...
17votes
4answers
47kviews
Which design pattern is more suitable for logging?
I should log some events in a program but as far as I know it would be better to keep the logging code outside the program because it is not about the real functionality of the program. So may you ...
- 311
1vote
1answer
549views
how to model a connection to a resource, with rudimentary event processing
For my simple MUD client I'm using Apache Telnet (no, not ssh). A mud client is a strange beast: Generally, a MUD client is a very basic telnet client that lacks VT100 terminal emulation and the ...
- 224
4votes
1answer
799views
Mutual observer pattern in Java
I want to improve my multi-threading and design pattern skills. As such I'm designing an Instant Messaging server. I'm writing the Server first. My plan so far is to have Client "Proxy" Classes to ...
- 387
