more

README.md

@@ -0,0 +1,5 @@
+# Kotlin Night Rochester 2019
+
+## Crash Course intro to Kotlin.
+
+Go through the intro subproject. Start in `io.mfj.kotlinnight.intro.Classes`

intro/src/main/java/io/mfj/kotlinnight/intro/Classes.kt

@@ -196,3 +196,5 @@ with comments. This is super nice.
 
  */
 // The comment ended there
+
+// Let's take a look at collections

intro/src/main/java/io/mfj/kotlinnight/intro/CollectionsIntro.kt

@@ -1,19 +1,27 @@
 package io.mfj.kotlinnight.intro
 
-// Objects are like static classes
-object CollectionsIntro {
+// Kotlin has its own set of collections that (in most cases) wrap the ones in java.util.
+// They can be mutable or immutable.
+// Immutability is important for functional programming.
 
-	// Kotlin has its own set of collections that (in most cases) wrap the ones in java.util.
-	// They can be mutable or immutable.
-	// Immutability is important for functional programming.
+// (Objects are singletons classes)
+object CollectionsIntro {
 
 	val someStuff = listOf( "a", "b", 0 )
 	// someStuff is mutable.
 	// what is the type? (show hints)
 
-	fun test() {
+	@JvmStatic
+	fun main( args:Array<String> ) {
 		val thisCanChange = mutableListOf("a", "b", "c")
-		thisCanChange.plus("d")
+		thisCanChange.add("d")
+
+		//someStuff.add("d")
+
+		val someStuffPlusD = someStuff.plus("d")
+		for ( x in someStuffPlusD ) {
+			println(x)
+		}
 	}
 
 	val aMap:Map<String,Int> = mapOf( "a" to 1, "b" to 2, "c" to 3 )

intro/src/main/java/io/mfj/kotlinnight/intro/Functional.kt

@@ -25,4 +25,24 @@ object Functional {
 
 	// let's make the body take a parameter and return something
 
-}
+}
+
+// You can define functions in any scope
+object InnerFUnction{
+
+	@JvmStatic
+	fun main( args:Array<String> ) {
+
+		listOf( "Tom", "Dick","Harry", "Sally" ).forEach { name ->
+
+			fun say(text:String) {
+				println( "${name} said \"${text}\"" )
+			}
+
+			say("Hello")
+			say("Goodbye")
+
+		}
+
+	}
+}

intro/src/main/java/io/mfj/kotlinnight/intro/X.kt

@@ -0,0 +1,37 @@
+package io.mfj.kotlinnight.intro
+
+// Kotlin lets you add functions to existing classes with Extension Functions
+
+// This is the syntax to create one:
+
+fun String.excite():String = "${this}!!!!!!!"
+
+object Ext {
+
+	@JvmStatic
+	fun main( args:Array<String> ) {
+
+		// You can call it just like any other function
+		println( "hello world".excite() )
+	}
+
+}
+
+// Classes can contain extension functions, and they are in the class' scope
+class Foo( private val name:String ) {
+
+	// This extension function has access to the instance.
+	fun String.said() = "${name} said \"${this}.\""
+
+	fun sayHello() {
+		println( "hello world".said() )
+	}
+
+	companion object {
+		@JvmStatic
+		fun main( args:Array<String> ) {
+			Foo("John").sayHello()
+		}
+	}
+
+}