Kotlin is a statically typed programming language that runs on the Java virtual machine, known as the Android world Swift designed, developed and open source by JetBrains .
Kotlin can be compiled into Java bytecode or into JavaScript, making it easyto run on devices without JVM.
In Google I Dot O 2017, Google announced Kotlin program files to Simplicity: greatly reduces the amount of boilerplate code. Security: avoid errors of the entire class, such as null pointer exceptions. Interoperability: take full advantage of existing libraries of JVM, Android,and browsers. Tool-friendly: can be built with any Java IDE or using the command line. Kotlin become the official development language of Android. 3.1.1. My first Kotlin program #
.kt the end, such as: hello.kt 、 app.kt .Simplest version #
package hello // Optional Baotou fun main(args: Array<String>) { // A package level visible function that accepts an array of strings as parameters println("Hello World!") // Semicolons can be omitted }
object-oriented #
class Greeter(val name: String) { fun greet() { println("Hello, $name") } } fun main(args: Array<String>) { Greeter("World!").greet() // Creating an object without the new keyword }
3.1.2. Why choose Kotlin? #
3.1.3. Reference link #