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app/src/main/java/com/example/algorithmstudy/MainActivity.kt

@@ -1,24 +1,12 @@
 package com.example.algorithmstudy
 
-import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
-import android.util.Log
-import com.example.algorithmstudy.pattern.creation.builder.MailBuilder
+import androidx.appcompat.app.AppCompatActivity
 
 class MainActivity : AppCompatActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
-
-        buildMail()
-    }
-
-    private fun buildMail() {
-        MailBuilder("Bill gates")
-            .title("Hi bill!")
-            .build().also {
-                Log.d("patternTest", "Mail was built : $it")
-            }
     }
 }

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/iterator/Food.kt

@@ -0,0 +1,3 @@
+package com.example.algorithmstudy.pattern.behavoiral.iterator
+
+data class Food(val name: String)

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/iterator/FoodIterator.kt

@@ -0,0 +1,13 @@
+package com.example.algorithmstudy.pattern.behavoiral.iterator
+
+class FoodIterator(private val collection: List<Food>) : Iterator<Food> {
+    private var index = 0
+
+    override fun next(): Food {
+        return collection[index++]
+    }
+
+    override fun hasNext(): Boolean {
+        return index < collection.size
+    }
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/iterator/Iterator.kt

@@ -0,0 +1,6 @@
+package com.example.algorithmstudy.pattern.behavoiral.iterator
+
+interface Iterator<T : Any> {
+    fun next(): T
+    fun hasNext(): Boolean
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/memento/CareTaker.kt

@@ -0,0 +1,16 @@
+package com.example.algorithmstudy.pattern.behavoiral.memento
+
+/**
+ * caretaker : the object that keeps track of multiple memento. Like maintaining save points.
+ */
+class CareTaker {
+    private val stateList = mutableListOf<Memento>()
+
+    fun addMemento(memento: Memento) {
+        stateList.add(memento)
+    }
+
+    fun getMemento(index: Int): Memento {
+        return stateList[index]
+    }
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/memento/GenericCareTaker.kt

@@ -0,0 +1,16 @@
+package com.example.algorithmstudy.pattern.behavoiral.memento
+
+/**
+ *  기억하고자 하는 어느 클래스와도 사용 가능하도록 하는 GenericCareTaker
+ */
+class GenericCareTaker<T : Any> {
+    private val stateList = mutableListOf<T>()
+
+    fun addMemento(memento: T) {
+        stateList.add(memento)
+    }
+
+    fun getMemento(index: Int): T {
+        return stateList[index]
+    }
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/memento/GenericOriginator.kt

@@ -0,0 +1,16 @@
+package com.example.algorithmstudy.pattern.behavoiral.memento
+
+/**
+ *  기억하고자 하는 어느 클래스와도 사용 가능하도록 하는 GenericOriginator
+ */
+class GenericOriginator<T : Any> {
+    var state: T? = null
+
+    fun createMemento(): T {
+        return state!!
+    }
+
+    fun setMemento(memento: T) {
+        state = memento
+    }
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/memento/Memento.kt

@@ -0,0 +1,6 @@
+package com.example.algorithmstudy.pattern.behavoiral.memento
+
+/**
+ * memento : the object that is going to maintain the state of the originator. It is just a POJO.
+ */
+data class Memento(val state: String)

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/memento/MementoManager.kt

@@ -0,0 +1,19 @@
+package com.example.algorithmstudy.pattern.behavoiral.memento
+
+/**
+ *  Generic 타입을 사용함과 동시에 패턴의 취지를 유지하며, 사용 방식을 보다 일원화 하도록 하는 Manager object
+ */
+object MementoManager {
+    private val originator = GenericOriginator<Memento>()
+    private val careTaker = GenericCareTaker<Memento>()
+
+    // state를 설정함과 동시에 Memento를 생성, careTaker에 추가
+    fun setState(memento: Memento) {
+        originator.state = memento
+        careTaker.addMemento(originator.createMemento())
+    }
+
+    fun getState(index: Int): Memento {
+        return careTaker.getMemento(index)
+    }
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/memento/Originator.kt

@@ -0,0 +1,17 @@
+package com.example.algorithmstudy.pattern.behavoiral.memento
+
+/**
+ * originator : the object for which the state is to be saved. It creates the memento and uses it in the future to undo.
+ */
+class Originator {
+
+    var state: String? = null
+
+    fun createMemento(): Memento {
+        return Memento(state ?: "")
+    }
+
+    fun setMemento(memento: Memento) {
+        state = memento.state
+    }
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/strategy/Damage.kt

@@ -0,0 +1,3 @@
+package com.example.algorithmstudy.pattern.behavoiral.strategy
+
+abstract class Damage(val amount: Int, val criticalHit: Double)

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/strategy/Fireball.kt

@@ -0,0 +1,5 @@
+package com.example.algorithmstudy.pattern.behavoiral.strategy
+
+class Fireball : Skill {
+    override fun perform(target: Int): Damage = object : Damage(2000, 0.2) {}
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/strategy/Player.kt

@@ -0,0 +1,9 @@
+package com.example.algorithmstudy.pattern.behavoiral.strategy
+
+class Player {
+    fun attackWithSkill(skill: Skill, target: Int) {
+        skill.perform(target)
+
+        println("$skill attack! to $target")
+    }
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/strategy/Skill.kt

@@ -0,0 +1,5 @@
+package com.example.algorithmstudy.pattern.behavoiral.strategy
+
+interface Skill {
+    fun perform(target: Int): Damage
+}

app/src/main/java/com/example/algorithmstudy/pattern/behavoiral/strategy/ThunderStorm.kt

@@ -0,0 +1,5 @@
+package com.example.algorithmstudy.pattern.behavoiral.strategy
+
+class ThunderStorm : Skill {
+    override fun perform(target: Int): Damage = object : Damage(1000, 0.3) {}
+}

app/src/test/java/com/example/algorithmstudy/design_pattern/IteratorTest.kt

@@ -0,0 +1,24 @@
+package com.example.algorithmstudy.design_pattern
+
+import com.example.algorithmstudy.pattern.behavoiral.iterator.Food
+import com.example.algorithmstudy.pattern.behavoiral.iterator.FoodIterator
+import com.example.algorithmstudy.pattern.behavoiral.strategy.Fireball
+import com.example.algorithmstudy.pattern.behavoiral.strategy.Player
+import com.example.algorithmstudy.pattern.behavoiral.strategy.ThunderStorm
+import org.junit.Test
+
+/**
+ *  Iterator Pattern
+ */
+class IteratorTest {
+
+    @Test
+    fun testIterator() {
+        val foodCollection = mutableListOf(Food("Apple"), Food("Banana"), Food("Kiwi"))
+        val iterator = FoodIterator(foodCollection)
+
+        while (iterator.hasNext()) {
+            println(iterator.next())
+        }
+    }
+}

app/src/test/java/com/example/algorithmstudy/design_pattern/MementoTest.kt

@@ -0,0 +1,70 @@
+package com.example.algorithmstudy.design_pattern
+
+import com.example.algorithmstudy.pattern.behavoiral.memento.*
+import org.junit.Test
+
+/**
+ * @reference:  https://chercher.tech/kotlin/momento-design-pattern-kotlin
+ */
+class MementoTest {
+
+    @Test
+    fun testMemento() {
+        val originator = Originator()
+        originator.state = "Ironman"
+        var memento = originator.createMemento()
+        val careTaker = CareTaker()
+        careTaker.addMemento(memento)
+
+        originator.state = "Captain America"
+        originator.state = "Hulk"
+        memento = originator.createMemento()
+        careTaker.addMemento(memento)
+        originator.state = "Thor"
+        println("Originator Current State: " + originator.state!!)
+        println("Originator restoring to previous state...")
+        memento = careTaker.getMemento(1)
+        originator.setMemento(memento)
+        println("Originator Current State: " + originator.state!!)
+        println("Again restoring to previous state...")
+        memento = careTaker.getMemento(0)
+        originator.setMemento(memento)
+        println("Originator Current State: " + originator.state!!)
+    }
+
+    @Test
+    fun testGeneric() {
+        val originator = GenericOriginator<Memento>()
+        originator.state = Memento("Ironman")
+        var memento = originator.createMemento()
+        val careTaker = GenericCareTaker<Memento>()
+        careTaker.addMemento(memento)
+
+        originator.state = Memento("Captain America")
+        originator.state = Memento("Hulk")
+        memento = originator.createMemento()
+        careTaker.addMemento(memento)
+        originator.state = Memento("Thor")
+
+        println("Originator Current State: " + originator.state!!)
+        println("Originator restoring to previous state...")
+        memento = careTaker.getMemento(1)
+        originator.setMemento(memento)
+        println("Originator Current State: " + originator.state!!)
+        println("Again restoring to previous state...")
+        memento = careTaker.getMemento(0)
+        originator.setMemento(memento)
+        println("Originator Current State: " + originator.state!!)
+    }
+
+    @Test
+    fun testMananger() {
+        MementoManager.setState(Memento("Ironman"))
+        MementoManager.setState(Memento("Captain America"))
+        MementoManager.setState(Memento("Hulk"))
+
+        println(MementoManager.getState(2))
+        println(MementoManager.getState(1))
+        println(MementoManager.getState(0))
+    }
+}

app/src/test/java/com/example/algorithmstudy/design_pattern/StrategyTest.kt

@@ -0,0 +1,20 @@
+package com.example.algorithmstudy.design_pattern
+
+import com.example.algorithmstudy.pattern.behavoiral.strategy.Fireball
+import com.example.algorithmstudy.pattern.behavoiral.strategy.Player
+import com.example.algorithmstudy.pattern.behavoiral.strategy.ThunderStorm
+import org.junit.Test
+
+/**
+ *  Strategy Pattern
+ */
+class StrategyTest {
+
+    @Test
+    fun testStrategy() {
+        val player = Player()
+
+        player.attackWithSkill(ThunderStorm(), 2)
+        player.attackWithSkill(Fireball(), 1)
+    }
+}