BAEL-2217 forEach within forEach (#6166)

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()
+}
+
+