plopezgit / sprint3_t2_patterns_part_2

Design pattern study

Sprint3_T1_Patterns_Part_2

• Level 1

In all exercises, create a Gradle project with a Main class that demonstrates the use of the pattern (with any invocations that are needed).

observe

Design a system in which a Stock Exchange Agent (Observable) notifies several Stock Exchange agencies (Observers) of changes when the Stock Exchange goes up or down.

It is necessary for the Observable object to hold references to the Observers.

• Level 2

Callback

Simulates a payment gateway that receives an object encapsulating the payment method to be made: credit card, Paypal or bank account debt.

The gateway will invoke the payment without knowing the form and returning control to the parent class. The class that invokes the payment gateway will be a shoe store.

• Level 3

Dependency Injection

Design a class that displays the price of various items on the screen. Since you will have to show them in several types of currency as well.

Important

Make sure to add as a Dependency Injection a CurrencyConverter class that performs the price correction based on the currency exchange.

sprint3_t2_patterns_part_2's Issues

depedency injection implementation incomplete

@plopezgit re-think how to vary currency on the vending class or its dependency; this is key for the exercise.

n1Exe1 observer pattern

• https://refactoring.guru/design-patterns/observer
• https://www.tutorialspoint.com/design_pattern/observer_pattern.htm
• build gradle proyect dir

• creates interface Observable (add, remove, notify(trend as param))
• creates interface Observer (update)
• implements observable (param. Set, HashSet; notify method body iterates over Set to call observer.update() method )
• implements observer 1
• Demo on App
• Enhance -> add Stock entity

[Complement] Study IntelliJ tutorial

https://www.jetbrains.com/help/idea/discover-intellij-idea.html

n1Exe2 callback pattern

• https://java-design-patterns.com/patterns/callback/

• https://www.baeldung.com/java-callback-functions

• creates main class

• inital test and commit

• creates callback interface

• implements Callback interface

• creates entities

• ShoesShop

• PaymentGateway

• Payment extends PaymentGateway

• Junit gradle depenency configuration (https://kkjavatutorials.com/junit-5-with-gradle-dependency/)

• creates and run unit test

• final push to publishing

dependency injection pattern: unit tests

Ask Manel code review and work on its feedback

makes callback pattern demostration on main

ShoesShop shop = new ShoesShop();
	System.out.println(shop.executePayment(200, 1));
	System.out.println(shop.executePayment(200, 2));
	System.out.println(shop.executePayment(200, 3));

observer pattern: add Stock entity

#1 requires:

• add Stock entity

n1Exe3 dependency injection pattern

• https://www.youtube.com/watch?v=Mb1609xfv5Q
• creates initial entities/interfaces based on requirement
• create class that implement CurrencyConverter for every conversion dependency
• inject CurrencyConverter interface as dependency of Vending intance
• instances vending class passing a EuroDolarConverter