Homework 2

src/main/homework02/Builder.kt

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+
+class FoodOrder private constructor(
+    val bread: String = "Flat bread",
+    val condiments: String?,
+    val meat: String?,
+    val fish: String?) {
+
+    data class Builder(
+        var bread: String? = null,
+        var condiments: String? = null,
+        var meat: String? = null,
+        var fish: String? = null) {
+
+        fun bread(bread: String) = apply { this.bread = bread }
+        fun condiments(condiments: String) = apply { this.condiments = condiments }
+        fun meat(meat: String) = apply { this.meat = meat }
+        fun fish(fish: String) = apply { this.fish = fish }
+        fun build() = FoodOrder(bread, condiments, meat, fish)
+        fun randomBuild() = bread(bread ?: "dry")
+            .condiments(condiments ?: "pepper")
+            .meat(meat ?: "beef")
+            .fish(fish?: "Tilapia")
+            .build()
+    }
+}
+
+fun main() {
+    val foodOrder = FoodOrder.Builder()
+        .bread("white bread")
+        .meat("bacon")
+        .condiments("olive oil")
+        .build()
+}

src/main/homework02/Command.kt

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+class Light {
+    fun turnOn() {
+        kotlin.io.println("The light is on")
+    }
+
+    fun turnOff() {
+        kotlin.io.println("The light is off")
+    }
+}
+
+interface Command {
+    fun execute()
+}
+
+class TurnOnLightCommand(private val theLight: Light) : Command {
+    override fun execute() {
+        theLight.turnOn()
+    }
+}
+
+class TurnOffLightCommand(private val theLight: Light) : Command {
+    override fun execute() {
+        theLight.turnOff()
+    }
+}
+
+class Switch(private val flipUpCommand: Command, private val flipDownCommand: Command) {
+    fun flipUp() {
+        flipUpCommand.execute()
+    }
+
+    fun flipDown() {
+        flipDownCommand.execute()
+    }
+}
+
+fun main() {
+    val l = Light()
+    val switchUp: Command = TurnOnLightCommand(l)
+    val switchDown: Command = TurnOffLightCommand(l)
+    val s = Switch(switchUp, switchDown)
+
+    s.flipUp()
+    s.flipDown()
+}

src/main/homework02/Decorator.kt

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+
+interface MilkShake {
+    fun getTaste()
+}
+
+class ConcreteMilkShake : MilkShake {
+    override fun getTaste() {
+        println("It’s milk !")
+    }
+}
+open class MilkShakeDecorator(protected var milkShake: MilkShake) : MilkShake {
+    override fun getTaste() {
+        this.milkShake.getTaste()
+    }
+}
+
+class BananaMilkShake(m:MilkShake) : MilkShakeDecorator(m){
+
+    override public fun getTaste(){
+        super.getTaste ();
+        this.addTaste();
+        println(" It’s Banana milk shake !");
+    }
+    public fun addTaste(){
+        println(" Adding Banana flavor to the milk shake !");
+    }
+}
+
+public class PeanutButterMilkShake(m:MilkShake) : MilkShakeDecorator(m){
+
+    override public fun getTaste(){
+        super.getTaste ();
+        this.addTaste();
+        println(" It’s Peanut butter milk shake !");
+    }
+    public fun addTaste(){
+        println(" Adding Peanut butter flavor to the milk shake !");
+    }
+}
+
+fun main(args: Array<String>) {
+    val peanutMilkShake = PeanutButterMilkShake(ConcreteMilkShake())
+    peanutMilkShake.getTaste()
+    val bananaMilkShake = BananaMilkShake(ConcreteMilkShake())
+    bananaMilkShake.getTaste()
+}

src/main/homework02/Singleton.kt

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+package main.homework02
+
+class Singleton private constructor() {
+    companion object {
+        val instance:Singleton by lazy {
+            Singleton()
+        }
+    }
+}