[Week1][입문편] 4강 코틀린에서 람다를 다루는 방법 (#5)

양승민/입문/src/lec18/Fruit.kt

@@ -0,0 +1,8 @@
+package lec18
+
+data class Fruit(
+    val id: Long,
+    val name: String,
+    val factoryPrice: Long,
+    val currentPrice: Long
+)

양승민/입문/src/lec18/lec18Main.kt

@@ -0,0 +1,25 @@
+package lec18
+
+fun main() {
+    val fruits: List<Fruit> = listOf()
+    val apples = fruits.filterIndexed { idx, fruit ->
+        println(idx)
+        fruit.name == "사과"
+    }
+    val applePrices = fruits.filter { fruit -> fruit.name == "사과" }
+        .map { fruit -> fruit.currentPrice }
+
+    val applePricesWithIndex = fruits.filter { fruit -> fruit.name == "사과" }
+        .mapIndexed { idx, fruit ->
+            println(idx)
+            fruit.currentPrice
+        }
+
+    val isAllApple = fruits.all { fruit -> fruit.name == "사과" }
+    val isNoApple = fruits.none { fruit -> fruit.name == "사과" }
+
+    val map: Map<String, List<Long>> = fruits
+        .groupBy({ fruit -> fruit.name }, { fruit -> fruit.currentPrice })
+    val map2: Map<Long, Long> = fruits
+        .associateBy({fruit -> fruit.id}, { fruit -> fruit.currentPrice })
+}