Migrate from Java to Kotlin

README.md

@@ -3,14 +3,35 @@
 This project is designed to show step by step how to migrate from Java to Kotlin with
 Spring Boot.
 
-## [Step 0]((https://github.com/sdeleuze/spring-kotlin-deepdive)): The original Java application
+## [Step 1](https://github.com/sdeleuze/spring-kotlin-deepdive/tree/step1): Java to Kotlin
 
-* Simple blog with JSON HTTP API
-* Demo
-* Present the Java application software design
-* Reminders:
-	* No need for annotating constructor when single constructor for autowiring it (as of Spring 4.3), show 2 syntaxes
-	* `@RequestMapping` aliases: `@GetMapping`, `@PostMapping`, etc.
-* Reload via CTRL + F9 in IDEA
+Code:
+* No more semicolon at end of lines
+* Type suffixed with colon, as statically typed as Java, optional type inference
+* Show how to configure return type inference hints
+* Short syntax for declaring properties and initializing them from the primary constructor instead of super verbose mostly auto-generated POJO
+* [Data classes](https://kotlinlang.org/docs/reference/data-classes.html)
+* Syntax help using naturally immutable classes
+* `:` instead of `extends`
+* No need for `{ }` for empty classes / interfaces
+* `public` by the default
+* `fun` to declare functions
+* Better lambdas: `{ }` last parameter notation, lambda without collect, `it` default parameter
+* Constructor without `new`
+* `main()` top level method
+* `Utils` class -> [Kotlin extensions](https://kotlinlang.org/docs/reference/extensions.html) 
+* `.getBody()` -> `.body`
+* Meaningful function names between backticks
 
-**[Go to step 1: Java to Kotlin](https://github.com/sdeleuze/spring-kotlin-deepdive/tree/step1)**
+Build:
+* Dependencies:
+	* `kotlin-stdlib-jre8`
+	* `kotlin-reflect`
+	* `jackson-module-kotlin`
+* Plugins:
+	* `kotlin`
+	* `kotlin-spring`
+	* `kotlin-noarg`
+* Configure to build Java 8 bytecode
+
+**[Go to step 2: Spring Boot 2](https://github.com/sdeleuze/spring-kotlin-deepdive/tree/step2)**

build.gradle

@@ -1,27 +1,46 @@
 buildscript {
 	ext {
+		kotlinVersion = "1.1.51"
 		springBootVersion = "1.5.7.RELEASE"
 	}
 	repositories {
 		mavenCentral()
 	}
 	dependencies {
 		classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
+		classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${kotlinVersion}")
+		classpath("org.jetbrains.kotlin:kotlin-allopen:${kotlinVersion}")
+		classpath("org.jetbrains.kotlin:kotlin-noarg:${kotlinVersion}")
 	}
 }
 
-apply plugin: "java"
+apply plugin: "kotlin"
+apply plugin: "kotlin-spring"
+apply plugin: "kotlin-noarg"
 apply plugin: "org.springframework.boot"
 
 group = "io.spring"
 version = "1.0.0-SNAPSHOT"
-sourceCompatibility = 1.8
 
 repositories {
 	mavenCentral()
 }
 
+noArg {
+	annotation("org.springframework.data.mongodb.core.mapping.Document")
+}
+
+compileKotlin {
+	kotlinOptions.jvmTarget = "1.8"
+}
+compileTestKotlin {
+	kotlinOptions.jvmTarget = "1.8"
+}
+
 dependencies {
+	compile("org.jetbrains.kotlin:kotlin-stdlib-jre8")
+	compile("org.jetbrains.kotlin:kotlin-reflect")
+	compile("com.fasterxml.jackson.module:jackson-module-kotlin")
 	compile("org.springframework.boot:spring-boot-starter-actuator")
 	compile("org.springframework.boot:spring-boot-starter-data-mongodb")
 	compile("org.springframework.boot:spring-boot-starter-web")