Flyweight

src/main/kotlin/oop/Flyweight/Admiral.kt

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+package oop.Flyweight
+
+import java.awt.Point
+
+class Admiral : Soldier {
+  companion object {
+    val TYPE = 1
+  }
+  init {
+      Flyweight.objectInstances++
+  }
+
+  val attack = 6
+  val salary = 23000
+  override fun attack(currentPosition: Point, attackPosition: Point) {
+    currentPosition.move(attackPosition.x, attackPosition.y)
+  }
+
+}

src/main/kotlin/oop/Flyweight/Captain.kt

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+package oop.Flyweight
+
+import java.awt.Point
+
+class Captain : Soldier {
+  companion object {
+    val TYPE = 2
+  }
+  init {
+      Flyweight.objectInstances++
+  }
+
+  val attack = 10
+  val salary = 10000
+  override fun attack(currentPosition: Point, attackPosition: Point) {
+    currentPosition.move(attackPosition.x, attackPosition.y)
+  }
+
+}

src/main/kotlin/oop/Flyweight/Flyweight.kt

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+package oop.Flyweight
+
+import java.awt.Point
+class Flyweight{
+  companion object{
+    var objectInstances = 0
+  }
+}
+fun main(args: Array<String>) {
+  val soldiers = listOf(
+    SoldierClient(Admiral.TYPE),
+    SoldierClient(Admiral.TYPE),
+    SoldierClient(Captain.TYPE),
+    SoldierClient(Captain.TYPE),
+    SoldierClient(Admiral.TYPE),
+    SoldierClient(Admiral.TYPE)
+  )
+  soldiers[0].attack(Point(1,2))
+  soldiers[1].attack(Point(10,12))
+  soldiers[2].attack(Point(9,5))
+  soldiers[3].attack(Point(11,7))
+  soldiers[4].attack(Point(21,3))
+
+  System.out.println(Flyweight.objectInstances)
+
+}

src/main/kotlin/oop/Flyweight/Soldier.kt

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+package oop.Flyweight
+
+import java.awt.Point
+
+interface Soldier {
+  fun attack(currentPosition: Point, attackPosition: Point)
+}

src/main/kotlin/oop/Flyweight/SoldierClient.kt

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+package oop.Flyweight
+
+import org.jetbrains.annotations.TestOnly
+import java.awt.Point
+
+class SoldierClient(private val type: Int) {
+  private val soldier: Soldier = SoldierFactory.getSoldier(type)
+  private val currentPosition: Point = Point()
+
+  fun attack(attackPoint: Point){
+    soldier.attack(currentPosition,attackPoint)
+  }
+
+  @TestOnly
+  fun getSoldier() = soldier
+
+}

src/main/kotlin/oop/Flyweight/SoldierFactory.kt

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+package oop.Flyweight
+
+import org.jetbrains.annotations.TestOnly
+
+class SoldierFactory {
+  companion object {
+    var admiral: Admiral? = null
+    var captain: Captain? = null
+
+      fun getSoldier(type: Int): Soldier{
+      when(type){
+        1 -> {
+          if(admiral == null){
+            admiral = Admiral()
+          }
+          return admiral!!
+        }
+        2 -> {
+          if(captain == null){
+            captain = Captain()
+          }
+          return captain!!
+        }
+      }
+      throw IllegalArgumentException()
+    }
+
+    @TestOnly
+    fun clearInstances(){
+      admiral = null
+      captain = null
+    }
+  }
+
+
+}

src/test/kotlin/oop/Flyweigth/FlyweightPatternShould.kt

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+package oop.Flyweigth
+
+import oop.Flyweight.*
+import org.hamcrest.CoreMatchers.`is`
+import org.hamcrest.MatcherAssert.assertThat
+import org.junit.Before
+import org.junit.Test
+import java.util.*
+
+class FlyweightPatternShould {
+
+  @Before
+  fun initTests(){
+    Flyweight.objectInstances = 0
+    SoldierFactory.clearInstances()
+  }
+
+  @Test
+  fun `Have one instance when only one type of soldier is created`() {
+    SoldierClient(Admiral.TYPE)
+    SoldierClient(Admiral.TYPE)
+    SoldierClient(Admiral.TYPE)
+
+    assertThat(Flyweight.objectInstances, `is`(1))
+  }
+  @Test
+  fun `Have two instances when both types are created, no matter the number of soldiers`(){
+    (1..Random().nextInt(30)).forEach {
+      SoldierClient(Admiral.TYPE)
+      SoldierClient(Captain.TYPE)
+    }
+
+    assertThat(Flyweight.objectInstances, `is`(2))
+  }
+
+  @Test
+  fun `Have the same main object in two instances of the same type`(){
+    val soldierOne: SoldierClient = SoldierClient(Admiral.TYPE)
+    val soldierTwo: SoldierClient = SoldierClient(Admiral.TYPE)
+
+    assertThat(soldierOne.getSoldier(), `is`(soldierTwo.getSoldier()))
+  }
+}