---
title: 'Scala: A Better Java for Android'
teaser:
tags: android,scala
author: Mike Burns
published_on: 2011-05-25
---

**Stop writing Java for your Android apps!**

There are a slew of ways to build Android apps. The original Java way reigns
supreme but some alternatives are
[C++](http://developer.android.com/sdk/ndk/index.html),
[Mirah](https://github.com/mirah/pindah),
[Python](http://code.google.com/p/android-scripting/), [Titanium
Appcelerator](http://www.appcelerator.com/),
[Corona](http://www.anscamobile.com/), and so on.

And there's Scala.

Scala can be thought of as a better Java. To start with, you don't need as many
semicolons. But Scala gives you the power of modern abstractions. Traits,
implicits, type-checked null, blocks--everything you really need to get some
solid coding done.

(Briefly, the magic Android sauce is the
[scalaforandroid](http://code.google.com/p/scalaforandroid/) project.)

As an example of what Scala can do for your app, take this simple project: a
button which, when pressed, shows a toast:

```scala
    package com.thoughtbot.helloscala

    import _root_.android.app.Activity
    import _root_.android.os.Bundle
    import _root_.android.widget.Toast
    import _root_.android.view.View
    import _root_.android.view.View.OnClickListener
    import _root_.android.widget.Button

    class HelloActivity extends Activity {
      override def onCreate(savedInstanceState : Bundle) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main)

        val button = findViewById(R.id.button).asInstanceOf[Button]
        button.setOnClickListener(new View.OnClickListener() {
          def onClick(v : View) {
            Toast.makeText(this, "You have clicked the button",
            Toast.LENGTH_LONG).show()
          }
        })
      }
    }
```

This is basically the Java version without semicolons. But we can spruce it up
with a trait and an implicit:

```scala
    package com.thoughtbot.helloscala

    import _root_.android.app.Activity
    import _root_.android.view.View
    import _root_.android.view.View.OnClickListener

    trait FindView extends Activity {
      def findView [WidgetType] (id : Int) : WidgetType = {
        findViewById(id).asInstanceOf[WidgetType]
      }
    }

    class ViewWithOnClick(view : View) {
      def onClick(action : View => Any) = {
        view.setOnClickListener(new View.OnClickListener() {
          def onClick(v : View) { action(v) }
        })
      }
    }

    object FindView extends Activity {
      implicit def addOnClickToViews(view : View) =
        new ViewWithOnClick(view)
    }
```

This adds an `onClick` method to `Views` and a `findView` method for
`Activities`. _Life  just got a little more functional_:

```scala
    package com.thoughtbot.helloscala

    import _root_.android.app.Activity
    import _root_.android.os.Bundle
    import _root_.android.widget.Toast
    import _root_.android.view.View
    import _root_.android.widget.Button
    import FindView._

    class HelloActivity extends Activity with FindView {
      override def onCreate(savedInstanceState : Bundle) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main)

         findView[Button](R.id.button).onClick { view : View =>
            Toast.makeText(this, "You have clicked the button", Toast.LENGTH_LONG).show()
        }
      }
    }
```

Take this concept as far as you need: a `doInBackground` method for functions, a
`withState`-like function for PreferenceManager, a caching wrapper for <abbr
title="Uniform Resource Locator">URL</abbr>s--the  sky is the limit here.

So what's stopping you from using Scala for your Android app?