├── .gitignore ├── LICENSE ├── README.md ├── build.gradle ├── gradle └── wrapper │ ├── gradle-wrapper.jar │ └── gradle-wrapper.properties ├── gradlew ├── gradlew.bat ├── patterns ├── build.gradle └── src │ └── test │ └── kotlin │ ├── AbstractFactory.kt │ ├── Adapter.kt │ ├── Builder.kt │ ├── ChainOfResponsibility.kt │ ├── Command.kt │ ├── Composite.kt │ ├── Decorator.kt │ ├── Facade.kt │ ├── FactoryMethod.kt │ ├── Listener.kt │ ├── Mediator.kt │ ├── Memento.kt │ ├── ProtectionProxy.kt │ ├── Singleton.kt │ ├── State.kt │ ├── Strategy.kt │ └── Visitor.kt └── settings.gradle /.gitignore: -------------------------------------------------------------------------------- 1 | .gradle/ 2 | .idea/ 3 | out/ 4 | build/ 5 | *.iml 6 | local.properties 7 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | {one line to give the program's name and a brief idea of what it does.} 635 | Copyright (C) {year} {name of author} 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | {project} Copyright (C) {year} {fullname} 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Design Patterns In Kotlin 2 | 3 | #### :warning: New article about testing: [Unit Testing with Mockito 2](https://github.com/dbacinski/Android-Testing-With-Kotlin/blob/master/docs/Unit-Testing-Mockito.md) 4 | 5 | Project maintained by [@dbacinski](http://twitter.com/dbacinski) (Dariusz Baciński) 6 | 7 | Inspired by [Design-Patterns-In-Swift](https://github.com/ochococo/Design-Patterns-In-Swift) by [@nsmeme](http://twitter.com/nsmeme) (Oktawian Chojnacki) 8 | 9 | ## Table of Contents 10 | 11 | * [Behavioral Patterns](#behavioral) 12 | * [Observer / Listener](#observer--listener) 13 | * [Strategy](#strategy) 14 | * [Command](#command) 15 | * [State](#state) 16 | * [Chain of Responsibility](#chain-of-responsibility) 17 | * [Visitor](#visitor) 18 | * [Mediator](#mediator) 19 | * [Memento](#memento) 20 | * [Creational Patterns](#creational) 21 | * [Builder / Assembler](#builder--assembler) 22 | * [Factory Method](#factory-method) 23 | * [Singleton](#singleton) 24 | * [Abstract Factory](#abstract-factory) 25 | * [Structural Patterns](#structural) 26 | * [Adapter](#adapter) 27 | * [Decorator](#decorator) 28 | * [Facade](#facade) 29 | * [Protection Proxy](#protection-proxy) 30 | * [Composite](#composite) 31 | 32 | Behavioral 33 | ========== 34 | 35 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 36 | > 37 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 38 | 39 | [Observer / Listener](/patterns/src/test/kotlin/Listener.kt) 40 | -------- 41 | 42 | The observer pattern is used to allow an object to publish changes to its state. 43 | Other objects subscribe to be immediately notified of any changes. 44 | 45 | #### Example 46 | 47 | ```kotlin 48 | interface TextChangedListener { 49 | 50 | fun onTextChanged(oldText: String, newText: String) 51 | } 52 | 53 | class PrintingTextChangedListener : TextChangedListener { 54 | 55 | private var text = "" 56 | 57 | override fun onTextChanged(oldText: String, newText: String) { 58 | text = "Text is changed: $oldText -> $newText" 59 | } 60 | } 61 | 62 | class TextView { 63 | 64 | val listeners = mutableListOf() 65 | 66 | var text: String by Delegates.observable("") { _, old, new -> 67 | listeners.forEach { it.onTextChanged(old, new) } 68 | } 69 | } 70 | ``` 71 | 72 | #### Usage 73 | 74 | ```kotlin 75 | val textView = TextView().apply { 76 | listeners.add(PrintingTextChangedListener()) 77 | } 78 | 79 | with(textView) { 80 | text = "Lorem ipsum" 81 | text = "dolor sit amet" 82 | } 83 | ``` 84 | 85 | #### Output 86 | 87 | ``` 88 | Text is changed -> Lorem ipsum 89 | Text is changed Lorem ipsum -> dolor sit amet 90 | ``` 91 | 92 | [Strategy](/patterns/src/test/kotlin/Strategy.kt) 93 | ----------- 94 | 95 | The strategy pattern is used to create an interchangeable family of algorithms from which the required process is chosen at run-time. 96 | 97 | #### Example 98 | 99 | ```kotlin 100 | class Printer(private val stringFormatterStrategy: (String) -> String) { 101 | 102 | fun printString(string: String) { 103 | println(stringFormatterStrategy(string)) 104 | } 105 | } 106 | 107 | val lowerCaseFormatter: (String) -> String = { it.toLowerCase() } 108 | val upperCaseFormatter = { it: String -> it.toUpperCase() } 109 | ``` 110 | 111 | #### Usage 112 | 113 | ```kotlin 114 | val inputString = "LOREM ipsum DOLOR sit amet" 115 | 116 | val lowerCasePrinter = Printer(lowerCaseFormatter) 117 | lowerCasePrinter.printString(inputString) 118 | 119 | val upperCasePrinter = Printer(upperCaseFormatter) 120 | upperCasePrinter.printString(inputString) 121 | 122 | val prefixPrinter = Printer { "Prefix: $it" } 123 | prefixPrinter.printString(inputString) 124 | ``` 125 | 126 | #### Output 127 | 128 | ``` 129 | lorem ipsum dolor sit amet 130 | LOREM IPSUM DOLOR SIT AMET 131 | Prefix: LOREM ipsum DOLOR sit amet 132 | ``` 133 | 134 | [Command](/patterns/src/test/kotlin/Command.kt) 135 | ------- 136 | 137 | The command pattern is used to express a request, including the call to be made and all of its required parameters, in a command object. The command may then be executed immediately or held for later use. 138 | 139 | #### Example: 140 | 141 | ```kotlin 142 | interface OrderCommand { 143 | fun execute() 144 | } 145 | 146 | class OrderAddCommand(val id: Long) : OrderCommand { 147 | override fun execute() = println("Adding order with id: $id") 148 | } 149 | 150 | class OrderPayCommand(val id: Long) : OrderCommand { 151 | override fun execute() = println("Paying for order with id: $id") 152 | } 153 | 154 | class CommandProcessor { 155 | 156 | private val queue = ArrayList() 157 | 158 | fun addToQueue(orderCommand: OrderCommand): CommandProcessor = 159 | apply { 160 | queue.add(orderCommand) 161 | } 162 | 163 | fun processCommands(): CommandProcessor = 164 | apply { 165 | queue.forEach { it.execute() } 166 | queue.clear() 167 | } 168 | } 169 | ``` 170 | 171 | #### Usage 172 | 173 | ```kotlin 174 | CommandProcessor() 175 | .addToQueue(OrderAddCommand(1L)) 176 | .addToQueue(OrderAddCommand(2L)) 177 | .addToQueue(OrderPayCommand(2L)) 178 | .addToQueue(OrderPayCommand(1L)) 179 | .processCommands() 180 | ``` 181 | 182 | #### Output 183 | 184 | ``` 185 | Adding order with id: 1 186 | Adding order with id: 2 187 | Paying for order with id: 2 188 | Paying for order with id: 1 189 | ``` 190 | 191 | [State](/patterns/src/test/kotlin/State.kt) 192 | ------ 193 | 194 | The state pattern is used to alter the behaviour of an object as its internal state changes. 195 | The pattern allows the class for an object to apparently change at run-time. 196 | 197 | #### Example 198 | 199 | ```kotlin 200 | sealed class AuthorizationState 201 | 202 | object Unauthorized : AuthorizationState() 203 | 204 | class Authorized(val userName: String) : AuthorizationState() 205 | 206 | class AuthorizationPresenter { 207 | 208 | private var state: AuthorizationState = Unauthorized 209 | 210 | val isAuthorized: Boolean 211 | get() = when (state) { 212 | is Authorized -> true 213 | is Unauthorized -> false 214 | } 215 | 216 | val userName: String 217 | get() { 218 | val state = this.state //val enables smart casting of state 219 | return when (state) { 220 | is Authorized -> state.userName 221 | is Unauthorized -> "Unknown" 222 | } 223 | } 224 | 225 | fun loginUser(userName: String) { 226 | state = Authorized(userName) 227 | } 228 | 229 | fun logoutUser() { 230 | state = Unauthorized 231 | } 232 | 233 | override fun toString() = "User '$userName' is logged in: $isAuthorized" 234 | } 235 | ``` 236 | 237 | #### Usage 238 | 239 | ```kotlin 240 | val authorizationPresenter = AuthorizationPresenter() 241 | 242 | authorizationPresenter.loginUser("admin") 243 | println(authorizationPresenter) 244 | 245 | authorizationPresenter.logoutUser() 246 | println(authorizationPresenter) 247 | ``` 248 | 249 | #### Output 250 | 251 | ``` 252 | User 'admin' is logged in: true 253 | User 'Unknown' is logged in: false 254 | ``` 255 | 256 | [Chain of Responsibility](/patterns/src/test/kotlin/ChainOfResponsibility.kt) 257 | ----------------------- 258 | 259 | The chain of responsibility pattern is used to process varied requests, each of which may be dealt with by a different handler. 260 | 261 | #### Example 262 | 263 | ```kotlin 264 | interface HeadersChain { 265 | fun addHeader(inputHeader: String): String 266 | } 267 | 268 | class AuthenticationHeader(val token: String?, var next: HeadersChain? = null) : HeadersChain { 269 | 270 | override fun addHeader(inputHeader: String): String { 271 | token ?: throw IllegalStateException("Token should be not null") 272 | return inputHeader + "Authorization: Bearer $token\n" 273 | .let { next?.addHeader(it) ?: it } 274 | } 275 | } 276 | 277 | class ContentTypeHeader(val contentType: String, var next: HeadersChain? = null) : HeadersChain { 278 | 279 | override fun addHeader(inputHeader: String): String = 280 | inputHeader + "ContentType: $contentType\n" 281 | .let { next?.addHeader(it) ?: it } 282 | } 283 | 284 | class BodyPayload(val body: String, var next: HeadersChain? = null) : HeadersChain { 285 | 286 | override fun addHeader(inputHeader: String): String = 287 | inputHeader + body.let { next?.addHeader(it) ?: it } 288 | } 289 | ``` 290 | 291 | #### Usage 292 | 293 | ```kotlin 294 | //create chain elements 295 | val authenticationHeader = AuthenticationHeader("123456") 296 | val contentTypeHeader = ContentTypeHeader("json") 297 | val messageBody = BodyPayload("Body:\n{\n\"username\"=\"dbacinski\"\n}") 298 | 299 | //construct chain 300 | authenticationHeader.next = contentTypeHeader 301 | contentTypeHeader.next = messageBody 302 | 303 | //execute chain 304 | val messageWithAuthentication = 305 | authenticationHeader.addHeader("Headers with Authentication:\n") 306 | println(messageWithAuthentication) 307 | 308 | val messageWithoutAuth = 309 | contentTypeHeader.addHeader("Headers:\n") 310 | println(messageWithoutAuth) 311 | ``` 312 | 313 | #### Output 314 | 315 | ``` 316 | Headers with Authentication: 317 | Authorization: Bearer 123456 318 | ContentType: json 319 | Body: 320 | { 321 | "username"="dbacinski" 322 | } 323 | 324 | Headers: 325 | ContentType: json 326 | Body: 327 | { 328 | "username"="dbacinski" 329 | } 330 | ``` 331 | 332 | [Visitor](/patterns/src/test/kotlin/Visitor.kt) 333 | ------- 334 | 335 | The visitor pattern is used to separate a relatively complex set of structured data classes from the functionality that may be performed upon the data that they hold. 336 | 337 | #### Example 338 | 339 | ```kotlin 340 | interface ReportVisitable { 341 | fun accept(visitor: ReportVisitor): R 342 | } 343 | 344 | class FixedPriceContract(val costPerYear: Long) : ReportVisitable { 345 | override fun accept(visitor: ReportVisitor): R = visitor.visit(this) 346 | } 347 | 348 | class TimeAndMaterialsContract(val costPerHour: Long, val hours: Long) : ReportVisitable { 349 | override fun accept(visitor: ReportVisitor): R = visitor.visit(this) 350 | } 351 | 352 | class SupportContract(val costPerMonth: Long) : ReportVisitable { 353 | override fun accept(visitor: ReportVisitor): R = visitor.visit(this) 354 | } 355 | 356 | interface ReportVisitor { 357 | 358 | fun visit(contract: FixedPriceContract): R 359 | fun visit(contract: TimeAndMaterialsContract): R 360 | fun visit(contract: SupportContract): R 361 | } 362 | 363 | class MonthlyCostReportVisitor : ReportVisitor { 364 | 365 | override fun visit(contract: FixedPriceContract): Long = 366 | contract.costPerYear / 12 367 | 368 | override fun visit(contract: TimeAndMaterialsContract): Long = 369 | contract.costPerHour * contract.hours 370 | 371 | override fun visit(contract: SupportContract): Long = 372 | contract.costPerMonth 373 | } 374 | 375 | class YearlyReportVisitor : ReportVisitor { 376 | 377 | override fun visit(contract: FixedPriceContract): Long = 378 | contract.costPerYear 379 | 380 | override fun visit(contract: TimeAndMaterialsContract): Long = 381 | contract.costPerHour * contract.hours 382 | 383 | override fun visit(contract: SupportContract): Long = 384 | contract.costPerMonth * 12 385 | } 386 | ``` 387 | 388 | #### Usage 389 | 390 | ```kotlin 391 | val projectAlpha = FixedPriceContract(costPerYear = 10000) 392 | val projectGamma = TimeAndMaterialsContract(hours = 150, costPerHour = 10) 393 | val projectBeta = SupportContract(costPerMonth = 500) 394 | val projectKappa = TimeAndMaterialsContract(hours = 50, costPerHour = 50) 395 | 396 | val projects = arrayOf(projectAlpha, projectBeta, projectGamma, projectKappa) 397 | 398 | val monthlyCostReportVisitor = MonthlyCostReportVisitor() 399 | 400 | val monthlyCost = projects.map { it.accept(monthlyCostReportVisitor) }.sum() 401 | println("Monthly cost: $monthlyCost") 402 | assertThat(monthlyCost).isEqualTo(5333) 403 | 404 | val yearlyReportVisitor = YearlyReportVisitor() 405 | val yearlyCost = projects.map { it.accept(yearlyReportVisitor) }.sum() 406 | println("Yearly cost: $yearlyCost") 407 | assertThat(yearlyCost).isEqualTo(20000) 408 | ``` 409 | 410 | #### Output 411 | 412 | ``` 413 | Monthly cost: 5333 414 | Yearly cost: 20000 415 | ``` 416 | 417 | [Mediator](/patterns/src/test/kotlin/Mediator.kt) 418 | ------- 419 | 420 | Mediator design pattern is used to provide a centralized communication medium between different objects in a system. This pattern is very helpful in an enterprise application where multiple objects are interacting with each other. 421 | #### Example 422 | 423 | ```kotlin 424 | class ChatUser(private val mediator: ChatMediator, val name: String) { 425 | fun send(msg: String) { 426 | println("$name: Sending Message= $msg") 427 | mediator.sendMessage(msg, this) 428 | } 429 | 430 | fun receive(msg: String) { 431 | println("$name: Message received: $msg") 432 | } 433 | } 434 | 435 | class ChatMediator { 436 | 437 | private val users: MutableList = ArrayList() 438 | 439 | fun sendMessage(msg: String, user: ChatUser) { 440 | users 441 | .filter { it != user } 442 | .forEach { 443 | it.receive(msg) 444 | } 445 | } 446 | 447 | fun addUser(user: ChatUser): ChatMediator = 448 | apply { users.add(user) } 449 | 450 | } 451 | ``` 452 | 453 | #### Usage 454 | 455 | ```kotlin 456 | val mediator = ChatMediator() 457 | val john = ChatUser(mediator, "John") 458 | 459 | mediator 460 | .addUser(ChatUser(mediator, "Alice")) 461 | .addUser(ChatUser(mediator, "Bob")) 462 | .addUser(john) 463 | john.send("Hi everyone!") 464 | ``` 465 | 466 | #### Output 467 | 468 | ``` 469 | John: Sending Message= Hi everyone! 470 | Alice: Message received: Hi everyone! 471 | Bob: Message received: Hi everyone! 472 | ``` 473 | 474 | [Memento](/patterns/src/test/kotlin/Memento.kt) 475 | ------- 476 | 477 | The memento pattern is a software design pattern that provides the ability to restore an object to its previous state (undo via rollback). 478 | 479 | #### Example 480 | ```kotlin 481 | data class Memento(val state: String) 482 | 483 | class Originator(var state: String) { 484 | 485 | fun createMemento(): Memento { 486 | return Memento(state) 487 | } 488 | 489 | fun restore(memento: Memento) { 490 | state = memento.state 491 | } 492 | } 493 | 494 | class CareTaker { 495 | private val mementoList = ArrayList() 496 | 497 | fun saveState(state: Memento) { 498 | mementoList.add(state) 499 | } 500 | 501 | fun restore(index: Int): Memento { 502 | return mementoList[index] 503 | } 504 | } 505 | ``` 506 | 507 | #### Usage 508 | ```kotlin 509 | val originator = Originator("initial state") 510 | val careTaker = CareTaker() 511 | careTaker.saveState(originator.createMemento()) 512 | 513 | originator.state = "State #1" 514 | originator.state = "State #2" 515 | careTaker.saveState(originator.createMemento()) 516 | 517 | originator.state = "State #3" 518 | println("Current State: " + originator.state) 519 | assertThat(originator.state).isEqualTo("State #3") 520 | 521 | originator.restore(careTaker.restore(1)) 522 | println("Second saved state: " + originator.state) 523 | assertThat(originator.state).isEqualTo("State #2") 524 | 525 | originator.restore(careTaker.restore(0)) 526 | println("First saved state: " + originator.state) 527 | ``` 528 | 529 | #### Output 530 | ``` 531 | Current State: State #3 532 | Second saved state: State #2 533 | First saved state: initial state 534 | ``` 535 | 536 | Creational 537 | ========== 538 | 539 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 540 | > 541 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 542 | 543 | [Builder / Assembler](/patterns/src/test/kotlin/Builder.kt) 544 | ---------- 545 | 546 | The builder pattern is used to create complex objects with constituent parts that must be created in the same order or using a specific algorithm. 547 | An external class controls the construction algorithm. 548 | 549 | #### Example 550 | 551 | ```kotlin 552 | // Let's assume that Dialog class is provided by external library. 553 | // We have only access to Dialog public interface which cannot be changed. 554 | 555 | class Dialog { 556 | 557 | fun showTitle() = println("showing title") 558 | 559 | fun setTitle(text: String) = println("setting title text $text") 560 | 561 | fun setTitleColor(color: String) = println("setting title color $color") 562 | 563 | fun showMessage() = println("showing message") 564 | 565 | fun setMessage(text: String) = println("setting message $text") 566 | 567 | fun setMessageColor(color: String) = println("setting message color $color") 568 | 569 | fun showImage(bitmapBytes: ByteArray) = println("showing image with size ${bitmapBytes.size}") 570 | 571 | fun show() = println("showing dialog $this") 572 | } 573 | 574 | //Builder: 575 | class DialogBuilder() { 576 | constructor(init: DialogBuilder.() -> Unit) : this() { 577 | init() 578 | } 579 | 580 | private var titleHolder: TextView? = null 581 | private var messageHolder: TextView? = null 582 | private var imageHolder: File? = null 583 | 584 | fun title(init: TextView.() -> Unit) { 585 | titleHolder = TextView().apply { init() } 586 | } 587 | 588 | fun message(init: TextView.() -> Unit) { 589 | messageHolder = TextView().apply { init() } 590 | } 591 | 592 | fun image(init: () -> File) { 593 | imageHolder = init() 594 | } 595 | 596 | fun build(): Dialog { 597 | val dialog = Dialog() 598 | 599 | titleHolder?.apply { 600 | dialog.setTitle(text) 601 | dialog.setTitleColor(color) 602 | dialog.showTitle() 603 | } 604 | 605 | messageHolder?.apply { 606 | dialog.setMessage(text) 607 | dialog.setMessageColor(color) 608 | dialog.showMessage() 609 | } 610 | 611 | imageHolder?.apply { 612 | dialog.showImage(readBytes()) 613 | } 614 | 615 | return dialog 616 | } 617 | 618 | class TextView { 619 | var text: String = "" 620 | var color: String = "#00000" 621 | } 622 | } 623 | ``` 624 | 625 | #### Usage 626 | 627 | ```kotlin 628 | //Function that creates dialog builder and builds Dialog 629 | fun dialog(init: DialogBuilder.() -> Unit): Dialog { 630 | return DialogBuilder(init).build() 631 | } 632 | 633 | val dialog: Dialog = dialog { 634 | title { 635 | text = "Dialog Title" 636 | } 637 | message { 638 | text = "Dialog Message" 639 | color = "#333333" 640 | } 641 | image { 642 | File.createTempFile("image", "jpg") 643 | } 644 | } 645 | 646 | dialog.show() 647 | ``` 648 | 649 | #### Output 650 | 651 | ``` 652 | setting title text Dialog Title 653 | setting title color #00000 654 | showing title 655 | setting message Dialog Message 656 | setting message color #333333 657 | showing message 658 | showing image with size 0 659 | showing dialog Dialog@5f184fc6 660 | ``` 661 | 662 | [Factory Method](/patterns/src/test/kotlin/FactoryMethod.kt) 663 | ----------------- 664 | 665 | The factory pattern is used to replace class constructors, abstracting the process of object generation so that the type of the object instantiated can be determined at run-time. 666 | 667 | #### Example 668 | 669 | ```kotlin 670 | sealed class Country { 671 | object USA : Country() //Kotlin 1.0 could only be an inner class or object 672 | } 673 | 674 | object Spain : Country() //Kotlin 1.1 declared as top level class/object in the same file 675 | class Greece(val someProperty: String) : Country() 676 | data class Canada(val someProperty: String) : Country() //Kotlin 1.1 data class extends other class 677 | //object Poland : Country() 678 | 679 | class Currency( 680 | val code: String 681 | ) 682 | 683 | object CurrencyFactory { 684 | 685 | fun currencyForCountry(country: Country): Currency = 686 | when (country) { 687 | is Greece -> Currency("EUR") 688 | is Spain -> Currency("EUR") 689 | is Country.USA -> Currency("USD") 690 | is Canada -> Currency("CAD") 691 | } //try to add a new country Poland, it won't even compile without adding new branch to 'when' 692 | } 693 | ``` 694 | 695 | #### Usage 696 | 697 | ```kotlin 698 | val greeceCurrency = CurrencyFactory.currencyForCountry(Greece("")).code 699 | println("Greece currency: $greeceCurrency") 700 | 701 | val usaCurrency = CurrencyFactory.currencyForCountry(Country.USA).code 702 | println("USA currency: $usaCurrency") 703 | 704 | assertThat(greeceCurrency).isEqualTo("EUR") 705 | assertThat(usaCurrency).isEqualTo("USD") 706 | ``` 707 | 708 | #### Output 709 | 710 | ``` 711 | Greece currency: EUR 712 | US currency: USD 713 | UK currency: No Currency Code Available 714 | ``` 715 | 716 | [Singleton](/patterns/src/test/kotlin/Singleton.kt) 717 | ------------ 718 | 719 | The singleton pattern ensures that only one object of a particular class is ever created. 720 | All further references to objects of the singleton class refer to the same underlying instance. 721 | There are very few applications, do not overuse this pattern! 722 | 723 | #### Example: 724 | 725 | ```kotlin 726 | object PrinterDriver { 727 | init { 728 | println("Initializing with object: $this") 729 | } 730 | 731 | fun print() = println("Printing with object: $this") 732 | } 733 | ``` 734 | 735 | #### Usage 736 | 737 | ```kotlin 738 | println("Start") 739 | PrinterDriver.print() 740 | PrinterDriver.print() 741 | ``` 742 | 743 | #### Output 744 | 745 | ``` 746 | Start 747 | Initializing with object: PrinterDriver@6ff3c5b5 748 | Printing with object: PrinterDriver@6ff3c5b5 749 | Printing with object: PrinterDriver@6ff3c5b5 750 | ``` 751 | 752 | [Abstract Factory](/patterns/src/test/kotlin/AbstractFactory.kt) 753 | ------------------- 754 | 755 | The abstract factory pattern is used to provide a client with a set of related or dependant objects. 756 | The "family" of objects created by the factory are determined at run-time. 757 | 758 | #### Example 759 | 760 | ```kotlin 761 | interface Plant 762 | 763 | class OrangePlant : Plant 764 | 765 | class ApplePlant : Plant 766 | 767 | abstract class PlantFactory { 768 | abstract fun makePlant(): Plant 769 | 770 | companion object { 771 | inline fun createFactory(): PlantFactory = when (T::class) { 772 | OrangePlant::class -> OrangeFactory() 773 | ApplePlant::class -> AppleFactory() 774 | else -> throw IllegalArgumentException() 775 | } 776 | } 777 | } 778 | 779 | class AppleFactory : PlantFactory() { 780 | override fun makePlant(): Plant = ApplePlant() 781 | } 782 | 783 | class OrangeFactory : PlantFactory() { 784 | override fun makePlant(): Plant = OrangePlant() 785 | } 786 | ``` 787 | 788 | #### Usage 789 | 790 | ```kotlin 791 | val plantFactory = PlantFactory.createFactory() 792 | val plant = plantFactory.makePlant() 793 | println("Created plant: $plant") 794 | ``` 795 | 796 | #### Output 797 | 798 | ```kotlin 799 | Created plant: OrangePlant@4f023edb 800 | ``` 801 | 802 | Structural 803 | ========== 804 | 805 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 806 | > 807 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 808 | 809 | [Adapter](/patterns/src/test/kotlin/Adapter.kt) 810 | ---------- 811 | 812 | The adapter pattern is used to provide a link between two otherwise incompatible types by wrapping the "adaptee" with a class that supports the interface required by the client. 813 | 814 | #### Example 815 | 816 | ```kotlin 817 | interface Temperature { 818 | var temperature: Double 819 | } 820 | 821 | class CelsiusTemperature(override var temperature: Double) : Temperature 822 | 823 | class FahrenheitTemperature(var celsiusTemperature: CelsiusTemperature) : Temperature { 824 | 825 | override var temperature: Double 826 | get() = convertCelsiusToFahrenheit(celsiusTemperature.temperature) 827 | set(temperatureInF) { 828 | celsiusTemperature.temperature = convertFahrenheitToCelsius(temperatureInF) 829 | } 830 | 831 | private fun convertFahrenheitToCelsius(f: Double): Double = (f - 32) * 5 / 9 832 | 833 | private fun convertCelsiusToFahrenheit(c: Double): Double = (c * 9 / 5) + 32 834 | } 835 | 836 | ``` 837 | 838 | #### Usage 839 | 840 | ```kotlin 841 | val celsiusTemperature = CelsiusTemperature(0.0) 842 | val fahrenheitTemperature = FahrenheitTemperature(celsiusTemperature) 843 | 844 | celsiusTemperature.temperature = 36.6 845 | println("${celsiusTemperature.temperature} C -> ${fahrenheitTemperature.temperature} F") 846 | 847 | fahrenheitTemperature.temperature = 100.0 848 | println("${fahrenheitTemperature.temperature} F -> ${celsiusTemperature.temperature} C") 849 | ``` 850 | 851 | #### Output 852 | 853 | ``` 854 | 36.6 C -> 97.88000000000001 F 855 | 100.0 F -> 37.77777777777778 C 856 | ``` 857 | 858 | [Decorator](/patterns/src/test/kotlin/Decorator.kt) 859 | ------------ 860 | 861 | The decorator pattern is used to extend or alter the functionality of objects at run-time by wrapping them in an object of a decorator class. 862 | This provides a flexible alternative to using inheritance to modify behaviour. 863 | 864 | #### Example 865 | 866 | ```kotlin 867 | interface CoffeeMachine { 868 | fun makeSmallCoffee() 869 | fun makeLargeCoffee() 870 | } 871 | 872 | class NormalCoffeeMachine : CoffeeMachine { 873 | override fun makeSmallCoffee() = println("Normal: Making small coffee") 874 | 875 | override fun makeLargeCoffee() = println("Normal: Making large coffee") 876 | } 877 | 878 | //Decorator: 879 | class EnhancedCoffeeMachine(val coffeeMachine: CoffeeMachine) : CoffeeMachine by coffeeMachine { 880 | 881 | // overriding behaviour 882 | override fun makeLargeCoffee() { 883 | println("Enhanced: Making large coffee") 884 | coffeeMachine.makeLargeCoffee() 885 | } 886 | 887 | // extended behaviour 888 | fun makeCoffeeWithMilk() { 889 | println("Enhanced: Making coffee with milk") 890 | coffeeMachine.makeSmallCoffee() 891 | println("Enhanced: Adding milk") 892 | } 893 | } 894 | ``` 895 | 896 | #### Usage 897 | 898 | ```kotlin 899 | val normalMachine = NormalCoffeeMachine() 900 | val enhancedMachine = EnhancedCoffeeMachine(normalMachine) 901 | 902 | // non-overridden behaviour 903 | enhancedMachine.makeSmallCoffee() 904 | // overriding behaviour 905 | enhancedMachine.makeLargeCoffee() 906 | // extended behaviour 907 | enhancedMachine.makeCoffeeWithMilk() 908 | ``` 909 | 910 | #### Output 911 | 912 | ``` 913 | Normal: Making small coffee 914 | 915 | Enhanced: Making large coffee 916 | Normal: Making large coffee 917 | 918 | Enhanced: Making coffee with milk 919 | Normal: Making small coffee 920 | Enhanced: Adding milk 921 | ``` 922 | 923 | [Facade](/patterns/src/test/kotlin/Facade.kt) 924 | --------- 925 | 926 | The facade pattern is used to define a simplified interface to a more complex subsystem. 927 | 928 | #### Example 929 | 930 | ```kotlin 931 | class ComplexSystemStore(val filePath: String) { 932 | 933 | init { 934 | println("Reading data from file: $filePath") 935 | } 936 | 937 | val store = HashMap() 938 | 939 | fun store(key: String, payload: String) { 940 | store.put(key, payload) 941 | } 942 | 943 | fun read(key: String): String = store[key] ?: "" 944 | 945 | fun commit() = println("Storing cached data: $store to file: $filePath") 946 | } 947 | 948 | data class User(val login: String) 949 | 950 | //Facade: 951 | class UserRepository { 952 | val systemPreferences = ComplexSystemStore("/data/default.prefs") 953 | 954 | fun save(user: User) { 955 | systemPreferences.store("USER_KEY", user.login) 956 | systemPreferences.commit() 957 | } 958 | 959 | fun findFirst(): User = User(systemPreferences.read("USER_KEY")) 960 | } 961 | ``` 962 | 963 | #### Usage 964 | 965 | ```kotlin 966 | val userRepository = UserRepository() 967 | val user = User("dbacinski") 968 | userRepository.save(user) 969 | val resultUser = userRepository.findFirst() 970 | println("Found stored user: $resultUser") 971 | ``` 972 | 973 | #### Ouput 974 | 975 | ``` 976 | Reading data from file: /data/default.prefs 977 | Storing cached data: {USER_KEY=dbacinski} to file: /data/default.prefs 978 | Found stored user: User(login=dbacinski) 979 | ``` 980 | 981 | [Protection Proxy](/patterns/src/test/kotlin/ProtectionProxy.kt) 982 | ------------------ 983 | 984 | The proxy pattern is used to provide a surrogate or placeholder object, which references an underlying object. 985 | Protection proxy is restricting access. 986 | 987 | #### Example 988 | 989 | ```kotlin 990 | interface File { 991 | fun read(name: String) 992 | } 993 | 994 | class NormalFile : File { 995 | override fun read(name: String) = println("Reading file: $name") 996 | } 997 | 998 | //Proxy: 999 | class SecuredFile : File { 1000 | val normalFile = NormalFile() 1001 | var password: String = "" 1002 | 1003 | override fun read(name: String) { 1004 | if (password == "secret") { 1005 | println("Password is correct: $password") 1006 | normalFile.read(name) 1007 | } else { 1008 | println("Incorrect password. Access denied!") 1009 | } 1010 | } 1011 | } 1012 | ``` 1013 | 1014 | #### Usage 1015 | 1016 | ```kotlin 1017 | val securedFile = SecuredFile() 1018 | securedFile.read("readme.md") 1019 | 1020 | securedFile.password = "secret" 1021 | securedFile.read("readme.md") 1022 | ``` 1023 | 1024 | #### Ouput 1025 | 1026 | ``` 1027 | Incorrect password. Access denied! 1028 | Password is correct: secret 1029 | Reading file: readme.md 1030 | ``` 1031 | 1032 | 1033 | 1034 | [Composite](/patterns/src/test/kotlin/Composite.kt) 1035 | ------------------ 1036 | 1037 | The composite pattern is used to compose zero-or-more similar 1038 | objects so that they can be manipulated as one object. 1039 | 1040 | #### Example 1041 | 1042 | ```kotlin 1043 | 1044 | open class Equipment(private var price: Int, private var name: String) { 1045 | open fun getPrice(): Int = price 1046 | } 1047 | 1048 | 1049 | /* 1050 | [composite] 1051 | */ 1052 | 1053 | open class Composite(name: String) : Equipment(0, name) { 1054 | val equipments = ArrayList() 1055 | 1056 | fun add(equipment: Equipment) { 1057 | this.equipments.add(equipment) 1058 | } 1059 | 1060 | override fun getPrice(): Int { 1061 | return equipments.map { it.getPrice() }.sum() 1062 | } 1063 | } 1064 | 1065 | 1066 | /* 1067 | leafs 1068 | */ 1069 | 1070 | class Cabbinet : Composite("cabbinet") 1071 | class FloppyDisk : Equipment(70, "Floppy Disk") 1072 | class HardDrive : Equipment(250, "Hard Drive") 1073 | class Memory : Equipment(280, "Memory") 1074 | 1075 | 1076 | ``` 1077 | 1078 | #### Usage 1079 | 1080 | ```kotlin 1081 | var cabbinet = Cabbinet() 1082 | cabbinet.add(FloppyDisk()) 1083 | cabbinet.add(HardDrive()) 1084 | cabbinet.add(Memory()) 1085 | println(cabbinet.getPrice()) 1086 | ``` 1087 | 1088 | #### Ouput 1089 | 1090 | ``` 1091 | 600 1092 | ``` 1093 | 1094 | 1095 | 1096 | Info 1097 | ==== 1098 | 1099 | Descriptions from: [Gang of Four Design Patterns Reference Sheet](http://www.blackwasp.co.uk/GangOfFour.aspx) 1100 | -------------------------------------------------------------------------------- /build.gradle: -------------------------------------------------------------------------------- 1 | version '1.0-SNAPSHOT' 2 | 3 | buildscript { 4 | ext.kotlin_version = '1.3.50' 5 | 6 | repositories { 7 | mavenCentral() 8 | } 9 | dependencies { 10 | classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" 11 | } 12 | } 13 | -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.jar: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/dbacinski/Design-Patterns-In-Kotlin/b9a169e5ec754f17861c788294ae4f3bcbc052dd/gradle/wrapper/gradle-wrapper.jar -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.properties: -------------------------------------------------------------------------------- 1 | #Fri Jan 04 10:36:24 CET 2019 2 | distributionBase=GRADLE_USER_HOME 3 | distributionPath=wrapper/dists 4 | zipStoreBase=GRADLE_USER_HOME 5 | zipStorePath=wrapper/dists 6 | distributionUrl=https\://services.gradle.org/distributions/gradle-4.10.3-all.zip 7 | -------------------------------------------------------------------------------- /gradlew: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env sh 2 | 3 | ############################################################################## 4 | ## 5 | ## Gradle start up script for UN*X 6 | ## 7 | ############################################################################## 8 | 9 | # Attempt to set APP_HOME 10 | # Resolve links: $0 may be a link 11 | PRG="$0" 12 | # Need this for relative symlinks. 13 | while [ -h "$PRG" ] ; do 14 | ls=`ls -ld "$PRG"` 15 | link=`expr "$ls" : '.*-> \(.*\)$'` 16 | if expr "$link" : '/.*' > /dev/null; then 17 | PRG="$link" 18 | else 19 | PRG=`dirname "$PRG"`"/$link" 20 | fi 21 | done 22 | SAVED="`pwd`" 23 | cd "`dirname \"$PRG\"`/" >/dev/null 24 | APP_HOME="`pwd -P`" 25 | cd "$SAVED" >/dev/null 26 | 27 | APP_NAME="Gradle" 28 | APP_BASE_NAME=`basename "$0"` 29 | 30 | # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 31 | DEFAULT_JVM_OPTS="" 32 | 33 | # Use the maximum available, or set MAX_FD != -1 to use that value. 34 | MAX_FD="maximum" 35 | 36 | warn () { 37 | echo "$*" 38 | } 39 | 40 | die () { 41 | echo 42 | echo "$*" 43 | echo 44 | exit 1 45 | } 46 | 47 | # OS specific support (must be 'true' or 'false'). 48 | cygwin=false 49 | msys=false 50 | darwin=false 51 | nonstop=false 52 | case "`uname`" in 53 | CYGWIN* ) 54 | cygwin=true 55 | ;; 56 | Darwin* ) 57 | darwin=true 58 | ;; 59 | MINGW* ) 60 | msys=true 61 | ;; 62 | NONSTOP* ) 63 | nonstop=true 64 | ;; 65 | esac 66 | 67 | CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar 68 | 69 | # Determine the Java command to use to start the JVM. 70 | if [ -n "$JAVA_HOME" ] ; then 71 | if [ -x "$JAVA_HOME/jre/sh/java" ] ; then 72 | # IBM's JDK on AIX uses strange locations for the executables 73 | JAVACMD="$JAVA_HOME/jre/sh/java" 74 | else 75 | JAVACMD="$JAVA_HOME/bin/java" 76 | fi 77 | if [ ! -x "$JAVACMD" ] ; then 78 | die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME 79 | 80 | Please set the JAVA_HOME variable in your environment to match the 81 | location of your Java installation." 82 | fi 83 | else 84 | JAVACMD="java" 85 | which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 86 | 87 | Please set the JAVA_HOME variable in your environment to match the 88 | location of your Java installation." 89 | fi 90 | 91 | # Increase the maximum file descriptors if we can. 92 | if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then 93 | MAX_FD_LIMIT=`ulimit -H -n` 94 | if [ $? -eq 0 ] ; then 95 | if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then 96 | MAX_FD="$MAX_FD_LIMIT" 97 | fi 98 | ulimit -n $MAX_FD 99 | if [ $? -ne 0 ] ; then 100 | warn "Could not set maximum file descriptor limit: $MAX_FD" 101 | fi 102 | else 103 | warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT" 104 | fi 105 | fi 106 | 107 | # For Darwin, add options to specify how the application appears in the dock 108 | if $darwin; then 109 | GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\"" 110 | fi 111 | 112 | # For Cygwin, switch paths to Windows format before running java 113 | if $cygwin ; then 114 | APP_HOME=`cygpath --path --mixed "$APP_HOME"` 115 | CLASSPATH=`cygpath --path --mixed "$CLASSPATH"` 116 | JAVACMD=`cygpath --unix "$JAVACMD"` 117 | 118 | # We build the pattern for arguments to be converted via cygpath 119 | ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null` 120 | SEP="" 121 | for dir in $ROOTDIRSRAW ; do 122 | ROOTDIRS="$ROOTDIRS$SEP$dir" 123 | SEP="|" 124 | done 125 | OURCYGPATTERN="(^($ROOTDIRS))" 126 | # Add a user-defined pattern to the cygpath arguments 127 | if [ "$GRADLE_CYGPATTERN" != "" ] ; then 128 | OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)" 129 | fi 130 | # Now convert the arguments - kludge to limit ourselves to /bin/sh 131 | i=0 132 | for arg in "$@" ; do 133 | CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -` 134 | CHECK2=`echo "$arg"|egrep -c "^-"` ### Determine if an option 135 | 136 | if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then ### Added a condition 137 | eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"` 138 | else 139 | eval `echo args$i`="\"$arg\"" 140 | fi 141 | i=$((i+1)) 142 | done 143 | case $i in 144 | (0) set -- ;; 145 | (1) set -- "$args0" ;; 146 | (2) set -- "$args0" "$args1" ;; 147 | (3) set -- "$args0" "$args1" "$args2" ;; 148 | (4) set -- "$args0" "$args1" "$args2" "$args3" ;; 149 | (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;; 150 | (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;; 151 | (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;; 152 | (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;; 153 | (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;; 154 | esac 155 | fi 156 | 157 | # Escape application args 158 | save () { 159 | for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done 160 | echo " " 161 | } 162 | APP_ARGS=$(save "$@") 163 | 164 | # Collect all arguments for the java command, following the shell quoting and substitution rules 165 | eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS" 166 | 167 | # by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong 168 | if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then 169 | cd "$(dirname "$0")" 170 | fi 171 | 172 | exec "$JAVACMD" "$@" 173 | -------------------------------------------------------------------------------- /gradlew.bat: -------------------------------------------------------------------------------- 1 | @if "%DEBUG%" == "" @echo off 2 | @rem ########################################################################## 3 | @rem 4 | @rem Gradle startup script for Windows 5 | @rem 6 | @rem ########################################################################## 7 | 8 | @rem Set local scope for the variables with windows NT shell 9 | if "%OS%"=="Windows_NT" setlocal 10 | 11 | set DIRNAME=%~dp0 12 | if "%DIRNAME%" == "" set DIRNAME=. 13 | set APP_BASE_NAME=%~n0 14 | set APP_HOME=%DIRNAME% 15 | 16 | @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 17 | set DEFAULT_JVM_OPTS= 18 | 19 | @rem Find java.exe 20 | if defined JAVA_HOME goto findJavaFromJavaHome 21 | 22 | set JAVA_EXE=java.exe 23 | %JAVA_EXE% -version >NUL 2>&1 24 | if "%ERRORLEVEL%" == "0" goto init 25 | 26 | echo. 27 | echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 28 | echo. 29 | echo Please set the JAVA_HOME variable in your environment to match the 30 | echo location of your Java installation. 31 | 32 | goto fail 33 | 34 | :findJavaFromJavaHome 35 | set JAVA_HOME=%JAVA_HOME:"=% 36 | set JAVA_EXE=%JAVA_HOME%/bin/java.exe 37 | 38 | if exist "%JAVA_EXE%" goto init 39 | 40 | echo. 41 | echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 42 | echo. 43 | echo Please set the JAVA_HOME variable in your environment to match the 44 | echo location of your Java installation. 45 | 46 | goto fail 47 | 48 | :init 49 | @rem Get command-line arguments, handling Windows variants 50 | 51 | if not "%OS%" == "Windows_NT" goto win9xME_args 52 | 53 | :win9xME_args 54 | @rem Slurp the command line arguments. 55 | set CMD_LINE_ARGS= 56 | set _SKIP=2 57 | 58 | :win9xME_args_slurp 59 | if "x%~1" == "x" goto execute 60 | 61 | set CMD_LINE_ARGS=%* 62 | 63 | :execute 64 | @rem Setup the command line 65 | 66 | set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar 67 | 68 | @rem Execute Gradle 69 | "%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS% 70 | 71 | :end 72 | @rem End local scope for the variables with windows NT shell 73 | if "%ERRORLEVEL%"=="0" goto mainEnd 74 | 75 | :fail 76 | rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of 77 | rem the _cmd.exe /c_ return code! 78 | if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1 79 | exit /b 1 80 | 81 | :mainEnd 82 | if "%OS%"=="Windows_NT" endlocal 83 | 84 | :omega 85 | -------------------------------------------------------------------------------- /patterns/build.gradle: -------------------------------------------------------------------------------- 1 | apply plugin: 'kotlin' 2 | 3 | repositories { 4 | mavenCentral() 5 | } 6 | 7 | sourceCompatibility = "8" 8 | targetCompatibility = "8" 9 | 10 | dependencies { 11 | implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8") 12 | implementation("org.jetbrains.kotlin:kotlin-reflect") 13 | testImplementation "org.junit.jupiter:junit-jupiter-api:5.3.2" 14 | testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:5.3.2" 15 | testImplementation("org.assertj:assertj-core:3.11.1") 16 | } 17 | 18 | test { 19 | // Enable JUnit 5 (Gradle 4.6+). 20 | useJUnitPlatform() 21 | 22 | // Always run tests, even when nothing changed. 23 | dependsOn 'cleanTest' 24 | 25 | // Show test results. 26 | testLogging { 27 | events "passed", "skipped", "failed" 28 | } 29 | } 30 | 31 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/AbstractFactory.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | 4 | //Based on: http://stackoverflow.com/a/13030163/361832 5 | 6 | interface Plant 7 | 8 | class OrangePlant : Plant 9 | 10 | class ApplePlant : Plant 11 | 12 | abstract class PlantFactory { 13 | 14 | abstract fun makePlant(): Plant 15 | 16 | companion object { 17 | inline fun createFactory(): PlantFactory = 18 | when (T::class) { 19 | OrangePlant::class -> OrangeFactory() 20 | ApplePlant::class -> AppleFactory() 21 | else -> throw IllegalArgumentException() 22 | } 23 | } 24 | } 25 | 26 | class AppleFactory : PlantFactory() { 27 | override fun makePlant(): Plant = ApplePlant() 28 | } 29 | 30 | class OrangeFactory : PlantFactory() { 31 | override fun makePlant(): Plant = OrangePlant() 32 | } 33 | 34 | 35 | class AbstractFactoryTest { 36 | 37 | @Test 38 | fun `Abstract Factory`() { 39 | val plantFactory = PlantFactory.createFactory() 40 | val plant = plantFactory.makePlant() 41 | println("Created plant: $plant") 42 | 43 | assertThat(plant).isInstanceOf(OrangePlant::class.java) 44 | } 45 | } 46 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Adapter.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | import java.math.BigDecimal 4 | 5 | interface Temperature { 6 | var temperature: Double 7 | } 8 | 9 | class CelsiusTemperature(override var temperature: Double) : Temperature 10 | 11 | class FahrenheitTemperature(private var celsiusTemperature: CelsiusTemperature) : Temperature { 12 | 13 | override var temperature: Double 14 | get() = convertCelsiusToFahrenheit(celsiusTemperature.temperature) 15 | set(temperatureInF) { 16 | celsiusTemperature.temperature = convertFahrenheitToCelsius(temperatureInF) 17 | } 18 | 19 | private fun convertFahrenheitToCelsius(f: Double): Double = 20 | ((BigDecimal.valueOf(f).setScale(2) - BigDecimal(32)) * BigDecimal(5) / BigDecimal(9)) 21 | .toDouble() 22 | 23 | 24 | private fun convertCelsiusToFahrenheit(c: Double): Double = 25 | ((BigDecimal.valueOf(c).setScale(2) * BigDecimal(9) / BigDecimal(5)) + BigDecimal(32)) 26 | .toDouble() 27 | } 28 | 29 | class AdapterTest { 30 | 31 | @Test 32 | fun Adapter() { 33 | val celsiusTemperature = CelsiusTemperature(0.0) 34 | val fahrenheitTemperature = FahrenheitTemperature(celsiusTemperature) 35 | 36 | celsiusTemperature.temperature = 36.6 37 | println("${celsiusTemperature.temperature} C -> ${fahrenheitTemperature.temperature} F") 38 | 39 | assertThat(fahrenheitTemperature.temperature).isEqualTo(97.88) 40 | 41 | fahrenheitTemperature.temperature = 100.0 42 | println("${fahrenheitTemperature.temperature} F -> ${celsiusTemperature.temperature} C") 43 | 44 | assertThat(celsiusTemperature.temperature).isEqualTo(37.78) 45 | } 46 | } 47 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Builder.kt: -------------------------------------------------------------------------------- 1 | import org.junit.jupiter.api.Test 2 | import java.io.File 3 | 4 | // Let's assume that Dialog class is provided by external library. 5 | // We have only access to Dialog public interface which cannot be changed. 6 | 7 | class Dialog { 8 | 9 | fun setTitle(text: String) = println("setting title text $text") 10 | fun setTitleColor(color: String) = println("setting title color $color") 11 | fun setMessage(text: String) = println("setting message $text") 12 | fun setMessageColor(color: String) = println("setting message color $color") 13 | fun setImage(bitmapBytes: ByteArray) = println("setting image with size ${bitmapBytes.size}") 14 | 15 | fun show() = println("showing dialog $this") 16 | } 17 | 18 | // Builder 19 | class DialogBuilder() { 20 | 21 | constructor(init: DialogBuilder.() -> Unit) : this() { 22 | init() 23 | } 24 | 25 | private var titleHolder: TextView? = null 26 | private var messageHolder: TextView? = null 27 | private var imageHolder: File? = null 28 | 29 | fun title(attributes: TextView.() -> Unit) { 30 | titleHolder = TextView().apply { attributes() } 31 | } 32 | 33 | fun message(attributes: TextView.() -> Unit) { 34 | messageHolder = TextView().apply { attributes() } 35 | } 36 | 37 | fun image(attributes: () -> File) { 38 | imageHolder = attributes() 39 | } 40 | 41 | fun build(): Dialog { 42 | println("build") 43 | val dialog = Dialog() 44 | 45 | titleHolder?.apply { 46 | dialog.setTitle(text) 47 | dialog.setTitleColor(color) 48 | } 49 | 50 | messageHolder?.apply { 51 | dialog.setMessage(text) 52 | dialog.setMessageColor(color) 53 | } 54 | 55 | imageHolder?.apply { 56 | dialog.setImage(readBytes()) 57 | } 58 | 59 | return dialog 60 | } 61 | 62 | class TextView { 63 | var text: String = "" 64 | var color: String = "#00000" 65 | } 66 | } 67 | 68 | //Function that creates dialog builder and builds Dialog 69 | fun dialog(init: DialogBuilder.() -> Unit): Dialog = 70 | DialogBuilder(init).build() 71 | 72 | class BuilderTest { 73 | 74 | @Test 75 | fun Builder() { 76 | 77 | println("Build dialog") 78 | 79 | val dialog: Dialog = 80 | dialog { 81 | title { 82 | text = "Dialog Title" 83 | } 84 | message { 85 | text = "Dialog Message" 86 | color = "#333333" 87 | } 88 | image { 89 | File.createTempFile("image", "jpg") 90 | } 91 | } 92 | 93 | println("Show dialog") 94 | 95 | dialog.show() 96 | } 97 | } -------------------------------------------------------------------------------- /patterns/src/test/kotlin/ChainOfResponsibility.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | 4 | interface HeadersChain { 5 | fun addHeader(inputHeader: String): String 6 | } 7 | 8 | class AuthenticationHeader(val token: String?, var next: HeadersChain? = null) : HeadersChain { 9 | 10 | override fun addHeader(inputHeader: String): String { 11 | token ?: throw IllegalStateException("Token should be not null") 12 | return inputHeader + "Authorization: Bearer $token\n" 13 | .let { next?.addHeader(it) ?: it } 14 | } 15 | } 16 | 17 | class ContentTypeHeader(val contentType: String, var next: HeadersChain? = null) : HeadersChain { 18 | 19 | override fun addHeader(inputHeader: String): String = 20 | inputHeader + "ContentType: $contentType\n" 21 | .let { next?.addHeader(it) ?: it } 22 | } 23 | 24 | class BodyPayload(val body: String, var next: HeadersChain? = null) : HeadersChain { 25 | 26 | override fun addHeader(inputHeader: String): String = 27 | inputHeader + body.let { next?.addHeader(it) ?: it } 28 | } 29 | 30 | class ChainOfResponsibilityTest { 31 | 32 | @Test 33 | fun `Chain Of Responsibility`() { 34 | //create chain elements 35 | val authenticationHeader = AuthenticationHeader("123456") 36 | val contentTypeHeader = ContentTypeHeader("json") 37 | val messageBody = BodyPayload("Body:\n{\n\"username\"=\"dbacinski\"\n}") 38 | 39 | //construct chain 40 | authenticationHeader.next = contentTypeHeader 41 | contentTypeHeader.next = messageBody 42 | 43 | //execute chain 44 | val messageWithAuthentication = 45 | authenticationHeader.addHeader("Headers with Authentication:\n") 46 | 47 | println(messageWithAuthentication) 48 | 49 | val messageWithoutAuth = 50 | contentTypeHeader.addHeader("Headers:\n") 51 | println(messageWithoutAuth) 52 | 53 | assertThat(messageWithAuthentication).isEqualTo( 54 | """ 55 | Headers with Authentication: 56 | Authorization: Bearer 123456 57 | ContentType: json 58 | Body: 59 | { 60 | "username"="dbacinski" 61 | } 62 | """.trimIndent() 63 | ) 64 | 65 | assertThat(messageWithoutAuth).isEqualTo( 66 | """ 67 | Headers: 68 | ContentType: json 69 | Body: 70 | { 71 | "username"="dbacinski" 72 | } 73 | """.trimIndent() 74 | ) 75 | } 76 | } 77 | 78 | 79 | 80 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Command.kt: -------------------------------------------------------------------------------- 1 | import org.junit.jupiter.api.Test 2 | import java.util.* 3 | 4 | interface OrderCommand { 5 | fun execute() 6 | } 7 | 8 | class OrderAddCommand(private val id: Long) : OrderCommand { 9 | override fun execute() = println("Adding order with id: $id") 10 | } 11 | 12 | class OrderPayCommand(private val id: Long) : OrderCommand { 13 | override fun execute() = println("Paying for order with id: $id") 14 | } 15 | 16 | class CommandProcessor { 17 | 18 | private val queue = ArrayList() 19 | 20 | fun addToQueue(orderCommand: OrderCommand): CommandProcessor = 21 | apply { 22 | queue.add(orderCommand) 23 | } 24 | 25 | fun processCommands(): CommandProcessor = 26 | apply { 27 | queue.forEach { it.execute() } 28 | queue.clear() 29 | } 30 | } 31 | 32 | class CommandTest { 33 | 34 | @Test 35 | fun Command() { 36 | CommandProcessor() 37 | .addToQueue(OrderAddCommand(1L)) 38 | .addToQueue(OrderAddCommand(2L)) 39 | .addToQueue(OrderPayCommand(2L)) 40 | .addToQueue(OrderPayCommand(1L)) 41 | .processCommands() 42 | } 43 | } 44 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Composite.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | 4 | open class Equipment( 5 | open val price: Int, 6 | val name: String 7 | ) 8 | 9 | open class Composite(name: String) : Equipment(0, name) { 10 | 11 | private val equipments = ArrayList() 12 | 13 | override val price: Int 14 | get() = equipments.map { it.price }.sum() 15 | 16 | 17 | fun add(equipment: Equipment) = 18 | apply { equipments.add(equipment) } 19 | } 20 | 21 | class PersonalComputer : Composite("PC") 22 | class Processor : Equipment(1070, "Processor") 23 | class HardDrive : Equipment(250, "Hard Drive") 24 | class Memory : Equipment(280, "Memory") 25 | 26 | 27 | class CompositeTest { 28 | 29 | @Test 30 | fun Composite() { 31 | val pc = PersonalComputer() 32 | .add(Processor()) 33 | .add(HardDrive()) 34 | .add(Memory()) 35 | 36 | println(pc.price) 37 | 38 | assertThat(pc.name).isEqualTo("PC") 39 | assertThat(pc.price).isEqualTo(1600) 40 | } 41 | } -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Decorator.kt: -------------------------------------------------------------------------------- 1 | import org.junit.jupiter.api.Test 2 | 3 | interface CoffeeMachine { 4 | fun makeSmallCoffee() 5 | fun makeLargeCoffee() 6 | } 7 | 8 | class NormalCoffeeMachine : CoffeeMachine { 9 | override fun makeSmallCoffee() = println("Normal: Making small coffee") 10 | 11 | override fun makeLargeCoffee() = println("Normal: Making large coffee") 12 | } 13 | 14 | //Decorator: 15 | class EnhancedCoffeeMachine(private val coffeeMachine: CoffeeMachine) : CoffeeMachine by coffeeMachine { 16 | 17 | // overriding behaviour 18 | override fun makeLargeCoffee() { 19 | println("Enhanced: Making large coffee") 20 | } 21 | 22 | // extended behaviour 23 | fun makeCoffeeWithMilk() { 24 | println("Enhanced: Making coffee with milk") 25 | coffeeMachine.makeSmallCoffee() 26 | addMilk() 27 | } 28 | 29 | private fun addMilk() { 30 | println("Enhanced: Adding milk") 31 | } 32 | } 33 | 34 | class DecoratorTest { 35 | 36 | @Test 37 | fun Decorator() { 38 | val normalMachine = NormalCoffeeMachine() 39 | val enhancedMachine = EnhancedCoffeeMachine(normalMachine) 40 | 41 | // non-overridden behaviour 42 | enhancedMachine.makeSmallCoffee() 43 | // overridden behaviour 44 | enhancedMachine.makeLargeCoffee() 45 | // extended behaviour 46 | enhancedMachine.makeCoffeeWithMilk() 47 | } 48 | } 49 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Facade.kt: -------------------------------------------------------------------------------- 1 | import org.junit.jupiter.api.Test 2 | 3 | class ComplexSystemStore(private val filePath: String) { 4 | 5 | private val cache: HashMap 6 | 7 | init { 8 | println("Reading data from file: $filePath") 9 | cache = HashMap() 10 | //read properties from file and put to cache 11 | } 12 | 13 | fun store(key: String, payload: String) { 14 | cache[key] = payload 15 | } 16 | 17 | fun read(key: String): String = cache[key] ?: "" 18 | 19 | fun commit() = println("Storing cached data: $cache to file: $filePath") 20 | } 21 | 22 | data class User(val login: String) 23 | 24 | //Facade: 25 | class UserRepository { 26 | 27 | private val systemPreferences = ComplexSystemStore("/data/default.prefs") 28 | 29 | fun save(user: User) { 30 | systemPreferences.store("USER_KEY", user.login) 31 | systemPreferences.commit() 32 | } 33 | 34 | fun findFirst(): User = User(systemPreferences.read("USER_KEY")) 35 | } 36 | 37 | class FacadeTest { 38 | 39 | @Test 40 | fun Facade() { 41 | val userRepository = UserRepository() 42 | val user = User("dbacinski") 43 | userRepository.save(user) 44 | val resultUser = userRepository.findFirst() 45 | println("Found stored user: $resultUser") 46 | } 47 | } -------------------------------------------------------------------------------- /patterns/src/test/kotlin/FactoryMethod.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | 4 | sealed class Country { 5 | object USA : Country() //Kotlin 1.0 could only be an inner class or object 6 | } 7 | 8 | object Spain : Country() //Kotlin 1.1 declared as top level class/object in the same file 9 | class Greece(val someProperty: String) : Country() 10 | data class Canada(val someProperty: String) : Country() //Kotlin 1.1 data class extends other class 11 | //object Poland : Country() 12 | 13 | class Currency( 14 | val code: String 15 | ) 16 | 17 | object CurrencyFactory { 18 | 19 | fun currencyForCountry(country: Country): Currency = 20 | when (country) { 21 | is Greece -> Currency("EUR") 22 | is Spain -> Currency("EUR") 23 | is Country.USA -> Currency("USD") 24 | is Canada -> Currency("CAD") 25 | } //try to add a new country Poland, it won't even compile without adding new branch to 'when' 26 | } 27 | 28 | class FactoryMethodTest { 29 | 30 | @Test 31 | fun FactoryMethod() { 32 | val greeceCurrency = CurrencyFactory.currencyForCountry(Greece("")).code 33 | println("Greece currency: $greeceCurrency") 34 | 35 | val usaCurrency = CurrencyFactory.currencyForCountry(Country.USA).code 36 | println("USA currency: $usaCurrency") 37 | 38 | assertThat(greeceCurrency).isEqualTo("EUR") 39 | assertThat(usaCurrency).isEqualTo("USD") 40 | } 41 | } -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Listener.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | import kotlin.properties.Delegates 4 | 5 | interface TextChangedListener { 6 | 7 | fun onTextChanged(oldText: String, newText: String) 8 | } 9 | 10 | class PrintingTextChangedListener : TextChangedListener { 11 | 12 | var text = "" 13 | 14 | override fun onTextChanged(oldText: String, newText: String) { 15 | text = "Text is changed: $oldText -> $newText" 16 | } 17 | } 18 | 19 | class TextView { 20 | 21 | val listeners = mutableListOf() 22 | 23 | var text: String by Delegates.observable("") { _, old, new -> 24 | listeners.forEach { it.onTextChanged(old, new) } 25 | } 26 | } 27 | 28 | class ListenerTest { 29 | 30 | @Test 31 | fun Listener() { 32 | val listener = PrintingTextChangedListener() 33 | 34 | val textView = TextView().apply { 35 | listeners.add(listener) 36 | } 37 | 38 | with(textView) { 39 | text = "Lorem ipsum" 40 | text = "dolor sit amet" 41 | } 42 | 43 | assertThat(listener.text).isEqualTo("Text is changed: Lorem ipsum -> dolor sit amet") 44 | } 45 | } 46 | 47 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Mediator.kt: -------------------------------------------------------------------------------- 1 | import org.junit.jupiter.api.Test 2 | 3 | class ChatUser(private val mediator: ChatMediator, private val name: String) { 4 | fun send(msg: String) { 5 | println("$name: Sending Message= $msg") 6 | mediator.sendMessage(msg, this) 7 | } 8 | 9 | fun receive(msg: String) { 10 | println("$name: Message received: $msg") 11 | } 12 | } 13 | 14 | class ChatMediator { 15 | 16 | private val users: MutableList = ArrayList() 17 | 18 | fun sendMessage(msg: String, user: ChatUser) { 19 | users 20 | .filter { it != user } 21 | .forEach { 22 | it.receive(msg) 23 | } 24 | } 25 | 26 | fun addUser(user: ChatUser): ChatMediator = 27 | apply { users.add(user) } 28 | 29 | } 30 | 31 | class MediatorTest { 32 | 33 | @Test 34 | fun Mediator() { 35 | val mediator = ChatMediator() 36 | 37 | val john = ChatUser(mediator, "John") 38 | 39 | mediator 40 | .addUser(ChatUser(mediator, "Alice")) 41 | .addUser(ChatUser(mediator, "Bob")) 42 | .addUser(john) 43 | 44 | john.send("Hi everyone!") 45 | } 46 | } -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Memento.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | 4 | data class Memento(val state: String) 5 | 6 | class Originator(var state: String) { 7 | 8 | fun createMemento(): Memento { 9 | return Memento(state) 10 | } 11 | 12 | fun restore(memento: Memento) { 13 | state = memento.state 14 | } 15 | } 16 | 17 | class CareTaker { 18 | private val mementoList = ArrayList() 19 | 20 | fun saveState(state: Memento) { 21 | mementoList.add(state) 22 | } 23 | 24 | fun restore(index: Int): Memento { 25 | return mementoList[index] 26 | } 27 | } 28 | 29 | class MementoTest { 30 | 31 | @Test 32 | fun Memento() { 33 | val originator = Originator("initial state") 34 | val careTaker = CareTaker() 35 | careTaker.saveState(originator.createMemento()) 36 | 37 | originator.state = "State #1" 38 | originator.state = "State #2" 39 | careTaker.saveState(originator.createMemento()) 40 | 41 | originator.state = "State #3" 42 | println("Current State: " + originator.state) 43 | assertThat(originator.state).isEqualTo("State #3") 44 | 45 | originator.restore(careTaker.restore(1)) 46 | println("Second saved state: " + originator.state) 47 | assertThat(originator.state).isEqualTo("State #2") 48 | 49 | originator.restore(careTaker.restore(0)) 50 | println("First saved state: " + originator.state) 51 | assertThat(originator.state).isEqualTo("initial state") 52 | } 53 | } -------------------------------------------------------------------------------- /patterns/src/test/kotlin/ProtectionProxy.kt: -------------------------------------------------------------------------------- 1 | import org.junit.jupiter.api.Test 2 | 3 | interface File { 4 | fun read(name: String) 5 | } 6 | 7 | class NormalFile : File { 8 | override fun read(name: String) = println("Reading file: $name") 9 | } 10 | 11 | //Proxy: 12 | class SecuredFile(private val normalFile: File) : File { 13 | var password: String = "" 14 | 15 | override fun read(name: String) { 16 | if (password == "secret") { 17 | println("Password is correct: $password") 18 | normalFile.read(name) 19 | } else { 20 | println("Incorrect password. Access denied!") 21 | } 22 | } 23 | } 24 | 25 | class ProtectionProxyTest { 26 | @Test 27 | fun `Protection Proxy`() { 28 | val securedFile = SecuredFile(NormalFile()) 29 | 30 | with(securedFile) { 31 | read("readme.md") 32 | password = "secret" 33 | read("readme.md") 34 | } 35 | } 36 | } -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Singleton.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | 4 | object PrinterDriver { 5 | init { 6 | println("Initializing with object: $this") 7 | } 8 | 9 | fun print(): PrinterDriver = 10 | apply { println("Printing with object: $this") } 11 | } 12 | 13 | class SingletonTest { 14 | 15 | @Test 16 | fun Singleton() { 17 | println("Start") 18 | val printerFirst = PrinterDriver.print() 19 | val printerSecond = PrinterDriver.print() 20 | 21 | assertThat(printerFirst).isSameAs(PrinterDriver) 22 | assertThat(printerSecond).isSameAs(PrinterDriver) 23 | } 24 | } 25 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/State.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | 4 | sealed class AuthorizationState 5 | 6 | object Unauthorized : AuthorizationState() 7 | 8 | class Authorized(val userName: String) : AuthorizationState() 9 | 10 | class AuthorizationPresenter { 11 | 12 | private var state: AuthorizationState = Unauthorized 13 | 14 | val isAuthorized: Boolean 15 | get() = when (state) { 16 | is Authorized -> true 17 | is Unauthorized -> false 18 | } 19 | 20 | val userName: String 21 | get() { 22 | return when (val state = this.state) { //val enables smart casting of state 23 | is Authorized -> state.userName 24 | is Unauthorized -> "Unknown" 25 | } 26 | } 27 | 28 | fun loginUser(userName: String) { 29 | state = Authorized(userName) 30 | } 31 | 32 | fun logoutUser() { 33 | state = Unauthorized 34 | } 35 | 36 | override fun toString() = "User '$userName' is logged in: $isAuthorized" 37 | } 38 | 39 | class StateTest { 40 | 41 | @Test 42 | fun State() { 43 | val authorizationPresenter = AuthorizationPresenter() 44 | 45 | authorizationPresenter.loginUser("admin") 46 | println(authorizationPresenter) 47 | assertThat(authorizationPresenter.isAuthorized).isEqualTo(true) 48 | assertThat(authorizationPresenter.userName).isEqualTo("admin") 49 | 50 | authorizationPresenter.logoutUser() 51 | println(authorizationPresenter) 52 | assertThat(authorizationPresenter.isAuthorized).isEqualTo(false) 53 | assertThat(authorizationPresenter.userName).isEqualTo("Unknown") 54 | } 55 | } 56 | 57 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Strategy.kt: -------------------------------------------------------------------------------- 1 | import org.junit.jupiter.api.Test 2 | 3 | class Printer(private val stringFormatterStrategy: (String) -> String) { 4 | 5 | fun printString(string: String) { 6 | println(stringFormatterStrategy(string)) 7 | } 8 | } 9 | 10 | val lowerCaseFormatter: (String) -> String = { it.toLowerCase() } 11 | val upperCaseFormatter = { it: String -> it.toUpperCase() } 12 | 13 | class StrategyTest { 14 | 15 | @Test 16 | fun Strategy() { 17 | 18 | val inputString = "LOREM ipsum DOLOR sit amet" 19 | 20 | val lowerCasePrinter = Printer(lowerCaseFormatter) 21 | lowerCasePrinter.printString(inputString) 22 | 23 | val upperCasePrinter = Printer(upperCaseFormatter) 24 | upperCasePrinter.printString(inputString) 25 | 26 | val prefixPrinter = Printer { "Prefix: $it" } 27 | prefixPrinter.printString(inputString) 28 | } 29 | } 30 | 31 | -------------------------------------------------------------------------------- /patterns/src/test/kotlin/Visitor.kt: -------------------------------------------------------------------------------- 1 | import org.assertj.core.api.Assertions.assertThat 2 | import org.junit.jupiter.api.Test 3 | 4 | interface ReportVisitable { 5 | fun accept(visitor: ReportVisitor): R 6 | } 7 | 8 | class FixedPriceContract(val costPerYear: Long) : ReportVisitable { 9 | override fun accept(visitor: ReportVisitor): R = visitor.visit(this) 10 | } 11 | 12 | class TimeAndMaterialsContract(val costPerHour: Long, val hours: Long) : ReportVisitable { 13 | override fun accept(visitor: ReportVisitor): R = visitor.visit(this) 14 | } 15 | 16 | class SupportContract(val costPerMonth: Long) : ReportVisitable { 17 | override fun accept(visitor: ReportVisitor): R = visitor.visit(this) 18 | } 19 | 20 | interface ReportVisitor { 21 | 22 | fun visit(contract: FixedPriceContract): R 23 | fun visit(contract: TimeAndMaterialsContract): R 24 | fun visit(contract: SupportContract): R 25 | } 26 | 27 | class MonthlyCostReportVisitor : ReportVisitor { 28 | 29 | override fun visit(contract: FixedPriceContract): Long = 30 | contract.costPerYear / 12 31 | 32 | override fun visit(contract: TimeAndMaterialsContract): Long = 33 | contract.costPerHour * contract.hours 34 | 35 | override fun visit(contract: SupportContract): Long = 36 | contract.costPerMonth 37 | } 38 | 39 | class YearlyReportVisitor : ReportVisitor { 40 | 41 | override fun visit(contract: FixedPriceContract): Long = 42 | contract.costPerYear 43 | 44 | override fun visit(contract: TimeAndMaterialsContract): Long = 45 | contract.costPerHour * contract.hours 46 | 47 | override fun visit(contract: SupportContract): Long = 48 | contract.costPerMonth * 12 49 | } 50 | 51 | class VisitorTest { 52 | 53 | @Test 54 | fun Visitor() { 55 | val projectAlpha = FixedPriceContract(costPerYear = 10000) 56 | val projectBeta = SupportContract(costPerMonth = 500) 57 | val projectGamma = TimeAndMaterialsContract(hours = 150, costPerHour = 10) 58 | val projectKappa = TimeAndMaterialsContract(hours = 50, costPerHour = 50) 59 | 60 | val projects = arrayOf(projectAlpha, projectBeta, projectGamma, projectKappa) 61 | 62 | val monthlyCostReportVisitor = MonthlyCostReportVisitor() 63 | 64 | val monthlyCost = projects.map { it.accept(monthlyCostReportVisitor) } 65 | .sum() 66 | println("Monthly cost: $monthlyCost") 67 | assertThat(monthlyCost).isEqualTo(5333) 68 | 69 | val yearlyReportVisitor = YearlyReportVisitor() 70 | val yearlyCost = projects.map { it.accept(yearlyReportVisitor) } 71 | .sum() 72 | println("Yearly cost: $yearlyCost") 73 | assertThat(yearlyCost).isEqualTo(20000) 74 | } 75 | } 76 | -------------------------------------------------------------------------------- /settings.gradle: -------------------------------------------------------------------------------- 1 | include ':patterns' 2 | rootProject.name = 'design-patterns-kotlin' 3 | --------------------------------------------------------------------------------