[2장_이지훈] 1일차 예제 파일 작성

Author: lee-ji-hoon

src/main/kotlin/ezhoon/chapter02/Customer.kt

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+package ezhoon.chapter02
+
+class Customer {
+
+}

src/main/kotlin/ezhoon/chapter02/Money.kt

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+package ezhoon.chapter02
+
+import java.math.BigDecimal
+
+/**
+ * TODO
+ *
+ * @property amount 가격 (BigDecimal은 Java언어에서 숫자를 정밀하게 저장하고 표현할 수 있는 유일한 방법이다.)
+ * - double도 소수점을 표현하지만 정밀도에 있어 한계가 있어 값 유실이 존재한다.
+ * - 돈과 소수점을 다룬다면 BigDecimal은 필수적이고 단점으로는 느린 속도와 기본 타입보다 조금 불편한 사용이다.
+ */
+class Money(
+    private val amount: BigDecimal
+) {
+
+    fun getWons(amount: Long): Money {
+        return Money(BigDecimal.valueOf(amount))
+    }
+
+    fun getWons(amount: Double): Money {
+        return Money(BigDecimal.valueOf(amount))
+    }
+
+    fun plus(other: Money): Money {
+        return Money(this.amount.add(other.amount))
+    }
+
+    fun minus(other: Money): Money {
+        return Money(this.amount.subtract(other.amount))
+    }
+
+    fun times(percent: Double): Money {
+        return Money(this.amount.multiply(BigDecimal(percent)))
+    }
+
+    fun isLessThan(other: Money) = amount < other.amount
+
+    fun isGreaterThan(other: Money) = amount >= other.amount
+}

src/main/kotlin/ezhoon/chapter02/Movie.kt

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+package ezhoon.chapter02
+
+import java.math.BigDecimal
+
+data class Movie(
+    val fee: Int
+) {
+    fun calculateMovieFee(screening: Screening): Money {
+        return Money(BigDecimal(10).plus(BigDecimal(screening.getMovieFee())))
+    }
+}

src/main/kotlin/ezhoon/chapter02/Reservation.kt

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+package ezhoon.chapter02
+
+class Reservation(
+    customer: Customer,
+    screening: Screening,
+    calculateFee: Money,
+    audienceCount: Int
+) {
+}

src/main/kotlin/ezhoon/chapter02/Screening.kt

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+package ezhoon.chapter02
+
+import java.time.LocalDateTime
+
+class Screening(
+    private val movie: Movie,
+    private val sequence: Int,
+    val whenScreened: LocalDateTime
+) {
+    fun isSequence(sequence: Int) = this.sequence == sequence
+
+    fun getMovieFee() = movie.fee
+
+    fun reserve(customer: Customer, audienceCount: Int): Reservation {
+        return Reservation(customer, this, calculateFee(audienceCount), audienceCount)
+    }
+
+    private fun calculateFee(audienceCount: Int): Money {
+        return movie.calculateMovieFee(this).times(audienceCount.toDouble())
+    }
+}