Dancing with Kotlin

What’s Kotlin?

Statically typed programming language for the JVM, Android and the browser. 100% interoperable with Java™

Why Kotlin?

  • Concise
    Drastically reduce the amount of boilerplate code you need to write.
  • Safe
    Avoid entire classes of errors such as null pointer exceptions.
  • Versatile
    Build server-side applications, Android apps or frontend code running in the browser.
  • Interoperable
    Leverage existing frameworks and libraries of the JVM with 100% Java Interoperability.
  • Tooling
    Command Line Compiler or First Class IDE Support. Freedom to choose.

How to?

Install kotlin plugin

First, if using Android Studio, you’ll need to install the Kotlin plugin. Go to File | Settings | Plugins | Install JetBrains plugin… and then search for and install Kotlin. You’ll need to restart the IDE after this completes.

How to install plugin

Creating a project

Just create an Android project from the IDE.

Converting Java code to Kotlin

  • Setup kotlin runtime, select “Confure Kotlin in Project”
    Setup Kotlin runtime
  • Select All modules
    Select modules
  • Convert Java file to Kotlin file
    Convert Java File to Kotlin File
  • The final code will be as following:
class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        val toolbar = findViewById(R.id.toolbar) as Toolbar

        val fab = findViewById(R.id.fab) as FloatingActionButton
        fab.setOnClickListener { view ->
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show()

    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        // Inflate the menu; this adds items to the action bar if it is present.
        menuInflater.inflate(R.menu.menu_main, menu)
        return true

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        val id = item.itemId

        if (id == R.id.action_settings) {
            return true

        return super.onOptionsItemSelected(item)

You can run the application with kotlin now

All the code you can find trevorwang/android-kotlin-example