From 96d4ae478d9f6f82cd9785ec9f64b5728385acc4 Mon Sep 17 00:00:00 2001
From: mikr <michael.krimgen@ximedes.com>
Date: Fri, 18 Jan 2019 00:23:08 +0100
Subject: [PATCH 1/2] BAEL-2217 forEach within forEach

---
 .../kotlin/com/baeldung/forEach/forEach.kt    | 61 +++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 core-kotlin/src/main/kotlin/com/baeldung/forEach/forEach.kt

diff --git a/core-kotlin/src/main/kotlin/com/baeldung/forEach/forEach.kt b/core-kotlin/src/main/kotlin/com/baeldung/forEach/forEach.kt
new file mode 100644
index 0000000000..ef56009c71
--- /dev/null
+++ b/core-kotlin/src/main/kotlin/com/baeldung/forEach/forEach.kt
@@ -0,0 +1,61 @@
+package com.baeldung.forEach
+
+
+class Country(val name : String, val cities : List<City>)
+
+class City(val name : String, val streets : List<String>)
+
+class World {
+
+    private val streetsOfAmsterdam = listOf("Herengracht", "Prinsengracht")
+    private val streetsOfBerlin = listOf("Unter den Linden","Tiergarten")
+    private val streetsOfMaastricht = listOf("Grote Gracht", "Vrijthof")
+    private val countries = listOf(
+            Country("Netherlands", listOf(City("Maastricht", streetsOfMaastricht),
+                    City("Amsterdam", streetsOfAmsterdam))),
+            Country("Germany", listOf(City("Berlin", streetsOfBerlin))))
+
+    fun allCountriesIt() {
+        countries.forEach { println(it.name) }
+    }
+
+    fun allCountriesItExplicit() {
+        countries.forEach { it -> println(it.name) }
+    }
+
+    //here we cannot refer to 'it' anymore inside the forEach
+    fun allCountriesExplicit() {
+        countries.forEach { c -> println(c.name) }
+    }
+
+    fun allNested() {
+        countries.forEach {
+            println(it.name)
+            it.cities.forEach {
+                println(" ${it.name}")
+                it.streets.forEach { println("  $it") }
+            }
+        }
+    }
+
+    fun allTable() {
+        countries.forEach { c ->
+            c.cities.forEach { p ->
+                p.streets.forEach { println("${c.name} ${p.name} $it") }
+            }
+        }
+    }
+}
+
+fun main(args : Array<String>) {
+
+    val world = World()
+
+    world.allCountriesExplicit()
+
+    world.allNested()
+
+    world.allTable()
+}
+
+

From 8cf72e2e7ee4e53dcd3a3b240231a5258945ec55 Mon Sep 17 00:00:00 2001
From: mikr <michael.krimgen@ximedes.com>
Date: Sat, 9 Mar 2019 17:18:23 +0100
Subject: [PATCH 2/2] BAEL-2217 forEach inside forEach in Kotlin: add flatMap
 example

---
 .../kotlin/com/baeldung/forEach/forEach.kt    | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/core-kotlin/src/main/kotlin/com/baeldung/forEach/forEach.kt b/core-kotlin/src/main/kotlin/com/baeldung/forEach/forEach.kt
index ef56009c71..20eda4e64f 100644
--- a/core-kotlin/src/main/kotlin/com/baeldung/forEach/forEach.kt
+++ b/core-kotlin/src/main/kotlin/com/baeldung/forEach/forEach.kt
@@ -5,6 +5,15 @@ class Country(val name : String, val cities : List<City>)
 
 class City(val name : String, val streets : List<String>)
 
+fun City.getStreetsWithCityName() : List<String> {
+    return streets.map { "$name, $it" }.toList()
+}
+
+fun Country.getCitiesWithCountryName() : List<String> {
+    return cities.flatMap { it.getStreetsWithCityName() }
+            .map { "$name, $it" }
+}
+
 class World {
 
     private val streetsOfAmsterdam = listOf("Herengracht", "Prinsengracht")
@@ -45,6 +54,19 @@ class World {
             }
         }
     }
+
+    fun allStreetsFlatMap() {
+
+        countries.flatMap { it.cities}
+                .flatMap { it.streets}
+                .forEach { println(it) }
+    }
+
+    fun allFlatMapTable() {
+
+        countries.flatMap { it.getCitiesWithCountryName() }
+                .forEach { println(it) }
+    }
 }
 
 fun main(args : Array<String>) {
@@ -56,6 +78,10 @@ fun main(args : Array<String>) {
     world.allNested()
 
     world.allTable()
+
+    world.allStreetsFlatMap()
+
+    world.allFlatMapTable()
 }