Java 11 support: Utilize new methods

[iluwatar]

This task is part of the Java 11 transition plan https://github.com/iluwatar/java-design-patterns/wiki/16.-Java-11-Transition

This is a refactoring ticket where we start to utilize new Java 11 functionality.

1. Collecting to unmodifiable collections is possible using the new Collector for Streams operations to put the results into an immutable collection (see https://www.infoq.com/articles/upgrading-java-8-to-12/)

2. Predicate::not provides an easy way to negate predicate lambdas or method references, again reducing the boilerplate in our code (see https://www.infoq.com/articles/upgrading-java-8-to-12/)

3. New methods on Optional give even more options for coding in a functional style when using an Optional instead of having to use clumsy if statements (see https://winterbe.com/posts/2018/09/24/java-11-tutorial/)

4. Streams have new methods ofNullable, dropWhile, takeWhile (see https://winterbe.com/posts/2018/09/24/java-11-tutorial/)

5. String has new helper methods (see https://winterbe.com/posts/2018/09/24/java-11-tutorial/)

6. InputStream finally gets a super useful method to transfer data to an OutputStream (see https://winterbe.com/posts/2018/09/24/java-11-tutorial/)

7. Convenience Factory Methods for Collections make it significantly easier to create collections like lists, maps and sets (see https://winterbe.com/posts/2018/09/24/java-11-tutorial/)

It's a huge task to do this for all the patterns at once so it is possible to create pull requests for individual patterns. This way we can complete the task gradually. The following checklist tracks which patterns have already been refactored.

[x] abstract-document
[x] abstract-factory
[x] acyclic-visitor
[x] adapter
[x] aggregator-microservices
[x] ambassador
[x] api-gateway
[x] async-method-invocation
[x] balking
[x] bridge
[x] builder
[x] business-delegate
[x] bytecode
[x] caching
[x] callback
[x] chain
[x] circuit-breaker
[x] collection-pipeline
[x] command
[x] commander
[x] composite
[x] converter
[x] cqrs
[x] dao
[x] data-bus
[x] data-locality
[x] data-mapper
[x] data-transfer-object
[x] decorator
[x] delegation
[x] dependency-injection
[x] dirty-flag
[x] double-checked-locking
[x] double-dispatch
[x] eip-aggregator
[x] eip-message-channel
[x] eip-publish-subscribe
[x] eip-splitter
[x] eip-wire-tap
[x] event-aggregator
[x] event-asynchronous
[x] event-driven-architecture
[x] event-queue
[x] event-sourcing
[x] execute-around
[x] extension-objects
[x] facade
[x] factory-kit
[x] factory-method
[x] faq.md
[x] feature-toggle
[x] fluentinterface
[x] flux
[x] flyweight
[x] front-controller
[x] guarded-suspension
[x] half-sync-half-async
[x] hexagonal
[x] intercepting-filter
[x] interpreter
[x] iterator
[x] layers
[x] lazy-loading
[x] leader-election
[x] marker
[x] master-worker-pattern
[x] mediator
[x] memento
[x] model-view-controller
[x] model-view-presenter
[x] module
[x] monad
[x] monostate
[x] multiton
[x] mute-idiom
[x] mutex
[x] naked-objects
[x] null-object
[x] object-mother
[x] object-pool
[x] observer
[x] page-object
[x] partial-response
[x] pipeline
[x] poison-pill
[x] priority-queue
[x] private-class-data
[x] producer-consumer
[x] promise
[x] property
[x] prototype
[x] proxy
[x] queue-load-leveling
[x] reactor
[x] reader-writer-lock
[x] repository
[x] resource-acquisition-is-initialization
[x] retry
[x] semaphore
[x] servant
[x] serverless
[x] service-layer
[x] service-locator
[x] singleton
[x] spatial-partition
[x] specification
[x] state
[x] step-builder
[x] strategy
[x] template-method
[x] thread-pool
[x] throttling
[x] tls
[x] tolerant-reader
[x] trampoline
[x] twin
[x] typeobjectpattern
[x] unit-of-work
[x] value-object
[x] visitor

[leonmak]

HI I would like to work on this, noticed it was combined from a few tickets, do I make a PR for each point?

[iluwatar]

Let's use the same gradual approach as we are doing in #984. You can do the refactoring for a single pattern or many. We'll then track the progress with a checklist.

@leonmak ok, you're good to go

[Anurag870]

@iluwatar I will work on the following patterns:
unit-of-work
value-object
visitor

[iluwatar]

Ok @Anurag870

[leonmak]

I would like to work on:

• abstract-document
• collection-pipeline
• commander
• composite
• converter

[leonmak]

Also would like to work on:

• dao
• double-dispatch
• facade
• flyweight

[Anurag870]

Also checked in code after checking

typeobjectpattern, tolerantreader, twin, trampoline

[iluwatar]

Ok @leonmak
@Anurag870 do you mean that code for those patterns has already been refactored?

[leonmak]

cool, thanks.
some more which I've worked on:

• hexagonal
• iterator
• layers
• leader-election
• observer
• page-object
• partial-response
• sample-application
• servant
• service-layer
• thread-pool

[anuragagarwal561994]

@iluwatar picked up ambassador async-method-invocation balking bridge builder in #1076

[anuragagarwal561994]

@iluwatar picked up remaining b-c in #1081

[anuragagarwal561994]

@iluwatar picked up starting with a in #1084

[anuragagarwal561994]

@iluwatar picked up from t-v in #1085

[anuragagarwal561994]

@iluwatar picked all c-e in #1111 and #1112

[anuragagarwal561994]

@iluwatar picked all f in #1115

[anuragagarwal561994]

@iluwatar picked remaining g,h,i in #1116

[anuragagarwal561994]

@iluwatar picked all s in #1120

[anuragagarwal561994]

@iluwatar picked q-r in #1121

[anuragagarwal561994]

@iluwatar picked all p in #1122

[anuragagarwal561994]

@iluwatar picked all m in #1220

[vINCENT8888801]

Hi, I am new to this project. May I work on [ ] null-object?

[anuragagarwal561994]

@iluwatar picked remaining patterns in #1479

[iluwatar]

Ok @anuragagarwal561994

[anuragagarwal561994]

@iluwatar finally is it time that we close this :D

[iluwatar]

@anuragagarwal561994 I really think so 😄 I'm grateful for your persistent effort on this 👍🏻