Mediator Design Pattern

[@derekbanas]

Thank you :) Yes, design patterns are learned through practice. When a programmer gets to the point in which they begin studying topics like patterns, refactoring, OOD, etc. they have to become an artist rather then a rule follower. Most programmers never progress to that point. Anyone can paint by numbers, but great programmers expand their canvas through practice. Just my opinion

[@pharoah327]

Well stated

[@derekbanas]

You are correct that String.equals should be used, but == works in this situation because the == operator checks whether the references to the objects are equal.

[@derekbanas]

You're very welcome :) I only do this because you guys have been so nice to me.

[@derekbanas]

Thank you very much. I'm glad you're finding it useful :)

[@derekbanas]

Thank you :) I'm glad you enjoy them. Yes you are correct it would be bad to eliminate that. At the time I deleted it just to get it out of the way.

[@derekbanas]

I have that tutorial in the works along with Spring, Hibernate and much more. I'll see what I can sneak in while I make my Android / Games / C tutorial. Thanks for the compliments :)

[@derekbanas]

Yes I should do an eclipse shortcut video. I try to avoid doing them only because I can never count on people seeing past tutorials. I try to make self contained videos whenever possible.

[@ozgunozankilic]

I have a very different educational background and I had serious doubts when I took the software design patterns course last semester. Your videos really helped me to understand design patterns and pass the course. Thanks a lot.

[@derekbanas]

I'm very happy I could be of help :)

[@ozgunozankilic]

@@derekbanas Update in 2018: I am now assigned as the TA of the course. Better re-watch these.

[@hurricanos13]

Very nice tutorial, this is ever the best video tutorial covering such confusing subject for software developers.

[@derekbanas]

If you made it all the way to the design patterns tutorials youre ready for Android. The only thing that seems to confuse people is the heavy use of the MVC pattern. If you're comfortable with that you shouldn't have any problems. Feel free to ask me questions

[@derekbanas]

Yes you are correct.

[@sharathkumar9876]

Hi Derek! Thank you so much. I cannot tell you how much your tutorials have helped me :)

[@derekbanas]

You're very welcome as always :)

[@StrangerSaret]

This video deserves like even for Colleagues classes names))

[@smuralimohan1]

Hi Derek, a thing about shortcuts. In eclipse, the getter/setter methods and constructor can be created in a single click by placing the mouse inside the class body, right-click->source->Generate Getters and Setters and right-click->source->Generate Constructor using fields. I am sure you must be aware of those, but if included in your videos, other viewers too can learn.

[@riteshk9879]

need a simpler example

[@ashrasmun1]

There are two guys and they talk with mediator only. They can give stuff to him or get stuff from him. I cannot imagine a simpler example.

[@PENDANTturnips]

I cant tell if im stupid but I get lost in a lot of this guys videos.

[@Noname0324]

Same here, I found his videos explains very little in the big picture and ideas, instead he just jumps into a lot of coding after the first 20 seconds or so.

[@hexrcs2641]

It feels like a server-clients pattern...

[@hexrcs2641]

Wait, feels like a mediator is like the bittorrent tracker and the colleagues are the peers

[@bryantkong4642]

hey,teacher Derek. I have finished all your design pattern tutorials today, it is really helpful.

[@derekbanas]

siyi Kong Thank you :) I'm very happy that I could help.

[@derekbanas]

Thank you :) I very much appreciate that

[@herp_derpingson]

Many of these Design Patterns are so similar that its easy to get confused :)

[@sunmustbedestroyed]

I have watched SooooOoo many of your videos now that "Well, hello internet!" and "please leave any questions or comments in the comments' section below: otherwise till next time." are now firmly ingrained in the speech centers of my brain (a bit like ghosting/retention of a menu on a plasma TV screen). I love it though!

[@derekbanas]

John Thank you :) Many more videos are coming.

[@usmansbk]

I see Mediator patter as basically dependency inversion principle

[@Floyd-df2uq]

Spot on. I was thinking the same thing.

[@noherczeg]

I'm so grateful for your channel! It's a really nice thing to see someone use examples outside of the bullshit todo app stuff.

[@derekbanas]

You're very welcome :)

[@jamiemarshall8284]

In this pattern - wouldn't you need to make your Mediator a singleton? BTW - love these. It's like tutorials for programmers.

[@tonyzhao904]

The video is awesome. I only spot one missing line of code in the video, which is: in "Colleague.java", the constructor doesn't have: mediator.addColleague(this); This would cause the collegecode number never reaches 2 or even 1 as shown in the results. But code in the given link is correct. Thanks again for the tutorial.

[@subhashkonda5000]

Whats the use of colleguecode, seems to know who is the source but i haven't seen it is used. Basically how it will stop notifying the source.

[@hexrcs2641]

Why do you remove all the @override annotations?

[@derekbanas]

Sometimes I do things the long way to collect my thoughts. Its hard for me to talk and type at the same time sometimes :)

[@galtfilin2580]

סרטון מעולה! תודה רבה על העזרה! great video! you helped me a lot... thank you so much!

[@derekbanas]

+gal tfilin You're very welcome :)

[@glebsamsonov7696]

Very cool tutorial series. Don't know if somebody's already mentioned it but in this one you use reference comparison for strings and that only works because you use string literals like String s = "GOOG" so that same string object is taken from the string pool and reused. Otherwise for strings you should always use equals method.

[@123japanuser]

Sincere gratitude to you Sir. No medals for me ...a sorry fourth

[@xipity]

Dude.. Seriously... Is there a "donate" button or something... I admire you!

[@derekbanas]

Thank you very much :) There is no need to donate. If you don't mind turning off AdBlock, if you use it, I'd appreciate that. Otherwise it is my pleasure to help.

[@sharathkumar9876]

Hi, is the mediator pattern particularly used to tackle objects that have many-to-many relationships?

[@pankajtiwari12]

Great presentation !

[@derekbanas]

Thank you :)

[@elysiafilm6215]

This is an awesome explanation! Thank you, very helpful :)

[@derekbanas]

Thank you :) Happy I could help

[@aloneirew]

Hey Derek, Love your videos and the way you teach those stuff, i've almost seen all you design pattern videos and im planning to start the UML next, thanks a lot for your time!. Btw - why do you remove the @override annotation sometimes?..seems like a bad practice..

[@anjana852]

Thank you! these videos are great !

[@derekbanas]

+anjana852 Thank you :) You're very welcome

[@eubor8539]

Just a question. Why did you removed "@Override" annotations?

[@pharoah327]

They aren't actually necessary. They are just there to give the compiler a hint as to the fact that you are trying to override a super class' (or an interface) method. If, for example, you spell the method name wrong or give it the wrong signature/header, the compiler will complain. Without @Override, if you make a mistake in the signature, the compiler will just think it is a new method and not give you any errors/warnings. So the @Override is just a safety in case you make a mistake.

[@pushkarajpatil4787]

Hello Derek, Thank you very much for this video, I have a question about this (mediator) design pattern, what is the role of colleague code while transaction is going on. I don's see any use apart from the print, is it really required?

[@laststandingdeplorablemgto3637]

Thanks for the vid. How is synchronization involved in this when Colleagues work in parallel? You need then synchronized methods in the Mediator, either on its entire class or on its internal resources if it is possible to get a more granular ie faster synchronization.

[@laststandingdeplorablemgto3637]

In your example you would probably synchronize upon Mediator.class because sell buy collections are interdependent of each other.

[@UCBCteam]

Hello Derek.... very nice videos I have learnet alot from your videos.. espacially, both java and design patterns... just wondering if you could give us some tutorials on JSP and Servlets... a bit advance level... thanks

[@Arsene013]

10 years old but still relevant

[@derekbanas]

Almost SawMan :)

[@jovcemalakovski9148]

Nice tutorial Derek, useful even today after 8 years. But what I've noticed is that you never used the addColleague method on the mediator and you got correct result in the console output. I was following the example in c# and got wrong colleagues codes, which makes sense because the add method was never used.

[@mohammedhasan946]

you gave me great help thank you

[@derekbanas]

You're very welcome :)

[@amirkobliansky4022]

great video! helped me a lot. tank you:)

[@derekbanas]

Amir Kobliansky Thank you :) I'm glad it helped

[@sayedthebacktracker]

hi.. Thank you for the video.. I have learned a lot.. Just a quick question.. I am desiging a protocol..which design pattern I can use for following scenerio? From my pc , I send request every milliseconds to another hardware.. then hardware send me response and I send acknowledgement for that request and do necessary task.. It is all about sending request and response.. It would be great help for me if you can give me some idea how to maintain it.. I am using Java RxTx API for serial communication.. Sorry for long message.. Thank you in advance

[@keent]

I know this is a 8 year old video but this still might find useful for someone. If you managed to got it to the end, you might wonder why your colleague code is `undefined` and found out that the video doesn’t show where to use the `addColleague` method. Here’s my simple solution (using JS Typescript btw): put this code `this.mediator.addColleague(this); ` inside your `Colleague` constructor. hope it helps :)

[@CyrilViXP]

It's really hard to find the case, when Mediator pattern can't be implemented as Observer

[@johnlock8496]

great tutorial

[@derekbanas]

john lock Thank you :)

[@smuralimohan1]

Which pairs of design patterns do you find similar/confusing? Could you please post your question so it gives us a chance to think about their nuances and get a better understanding of their applicability?

[@derekbanas]

You guys are funny :)

[@akshay288]

Derek Bansa seems to working for Ibank or providing service to ibanks

[@farazshah5651]

Awesome!!!

[@herp_derpingson]

You are the man Saw Man! XD

[@monicajanethsalasrodriguez6287]

#Hola Buena explicación.

[@derekbanas]

Mónica Janeth Salas Rodríguez Gracias :)

[@rickmonarch4552]

Could u make a chat program with this? :D

[@bigworldmemes]

yes, that's actually how chat programs work, you send data to the server, server sends it to the colleague that you specify, most chat programs aren't peer-to-peer

[@bigworldmemes]

server in this context is the mediator

[@bigworldmemes]

one might argue though, that with chat rooms you are communicating between 2 OBJECTS of the same type, not 2 CLASSES

[@CaponordRevHappy]

Simple, now that's explained!

[@derekbanas]

Thank you :)

[@AlphaMatt1000]

Ridiculously overcomplicated to demonstrate this pattern, and I have 25 years experience building software professionally for many large organizations.

[@MrChingy5555]

for some reason this looks alot like the observer pattern

[@AlexEttelis]

Did you know you can double click a word to select it? no need to select char by char :D

[@ziv4545]

what is GOF? 1

[@derekbanas]

This is the Gang of Four book amzn.to/2by0iZf

[@fancyjohn]

Like a dispatcher with event emitting/subscription

[@faithnassiwa]

Hi Derek! Great videos, they helped me understand better patterns i had failed to click. Do you have any video tutorials on:- 1. Data access Object (DAO) 2. Transfer Object pattern 3. Java Connector Architecture (JCA) 4. Service Starter Pattern 5. Payload Extractor Pattern ???

[@derekbanas]

+faith nassiwa Thank you :) Sorry I don't. I hope to cover them soon.

[@StormCraftable]

String comparrison with == ? o.O

[@zss123456789]

It's kind of funny because the nyse is the actual broker.

[@OverG88]

Ok.

[@Vendettaaaa666]

this is exact opposite of observer pattern.

[@minaamir2648]

example is used to explain the idea , now we need to explain the example .. !! need a simple example as airport

[@MusicalSawMen]

Second !!!!!!!!!!!!!!!!!!!!!!!!!

[@Tomas970506]

Your coding examples sometimes are far to much to explain people what you want to explain.

[@expertreviews1112]

wow i understood NOTHING! The example took me to moon and back.

[@Brainsucker92]

I had a massive cringe when I saw the string comparison via the "==" operator...

[@iforgot669]

But in many languages this is how you do do string comparisons and design patterns are language agnostic. Even if that's syntactically wrong in the case of Java i think it removes clutter for anyone coming from a different language. Not saying it was intentional, but I just don't see it as a problem for the use case of this video.

[@Brainsucker92]

@@iforgot669 It's not syntactically wrong but fuctionally wrong. The "==" operator simply does not do what your're trying to achieve in this context.

[@iforgot669]

@@Brainsucker92 So your saying it's the wrong syntax for comparison; as in, syntactically wrong. I didnt say it wouldn't compile.

[@Brainsucker92]

@@iforgot669 No, I'm saying it's the wrong functionality for comparison...