中文版 日本語

AndroidDemoIn4Languages

A simple Android application written in Java, Groovy, Scala and Kotlin in order to find out what is the better language for Android development.

ChangeLog

• 2017-03-30 Update versions: Android Sdk -> v25, Gradle Plugin -> v2.2.0, Kotlin -> v1.1.1, Groovy -> 2.4.10
• 2016-07-30 Update Scala, SBT, sbt-android versions
• 2016-05-19 Update Kotlin from v1.0.0 to v1.0.2

How to Compare?

Only import the minimal dependencies.

Dependence Report

• In Java
  • Import com.android.support:appcompat-v7:25.2.0
• In Groovy
  • Import com.android.support:appcompat-v7:25.2.0
  • Import org.codehaus.groovy:groovy:2.4.10:grooid
  • Import org.codehaus.groovy:groovy-json:2.4.10
• In Scala
  • Import com.android.support:appcompat-v7:25.2.0
  • Import org.scala-lang:scala-library:2.11.8
• In Kotlin
  • Import com.android.support:appcompat-v7:25.2.0
  • Import org.jetbrains.kotlin:kotlin-stdlib:1.1.1

Analysis Report

Line Counter

Size Counter

Method Counter

Build Speed

Test on MacBook Pro (Retina, 15-inch, Mid 2014 & APPLE SSD SM0256F Media)

Gradle task: ./gradlew :app:clean :app:assembleDebug SBT task: sbt app/clean app/android:package

Coding Comparison

Find View

Java

TextView title = (TextView)view.findViewById(android.R.id.text1);

Groovy

def title = view.findViewById(android.R.id.text1) as TextView

Scala

With Typed Resources enabled (include in Android SDK Plugin for SBT)

val title = view.findView(TR.text1)

Note: as a fallback, one can use the more traditional cast-based approach:

val title = view.findViewById(android.R.id.text1).asInstanceOf[TextView]

Kotlin

With Kotlin Android Extensions enabled (no extra dependencies needed):

val title = view.text1

Note: as a fallback, one can use the more traditional cast-based approach:

val title = view.findViewById(android.R.id.text1) as TextView

OnClickListener

Java

button.setOnClickListener(new View.OnClickListener() {
    @Override
    void onClick(final View v) {
      //  do something
    }
})

Groovy

button.onClickListener = {
    //  do something
}

Scala

button.onClick((v: View) =>
    //  do something
)

Kotlin

button.setOnClickListener {
    //  do something
}

Callback

Java

public interface FindCallback {
    void onFinish(List<String> results, Exception e);
}
private void findCountries(FindCallback doneCallback) {
    try {
        //  a long time mission
        doneCallback.onFinish(results, null);
    } catch (Exception e) {
        doneCallback.onFinish(null, e);
    }
}
findCountries(new FindCallback(){
    void onFinish(List<String> results, Exception e){
      //  handle result
    }
});

Groovy

def findCountries(Closure doneCallback) {
    try {
        //  a long time mission
        doneCallback(results, null)
    } catch (e) {
        doneCallback(null, e)
    }
}
findCountries{ List<String> results, Exception e ->
  //  handle result
});

Scala

def findCountries(doneCallback: (ArrayBuffer[String], Exception) => Unit):Unit = {
    try {
        //  a long time mission
        doneCallback(results, null)
    } catch {
        case e: Exception => doneCallback(null, e)
    }
}
findCountries((names: ArrayBuffer[String], e: Exception) =>
  //  handle result
)

Kotlin

fun findCountries(doneCallback: (List<String>?, Exception?) -> Unit) {
    try {
        //  a long time mission
        doneCallback(results, null)
    } catch (e: Exception) {
        doneCallback(null, e)
    }
}
findCountries{ list, e ->
  //  handle result
}

Extension

Scala

object AndroidContext {

  implicit class RichContext(ctx: Context) {
    def toast(msg: String) = Toast.makeText(ctx, msg, Toast.LENGTH_SHORT).show()

    def progress(): ProgressDialog = {
      val progressDialog = new ProgressDialog(ctx)
      progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER)
      progressDialog.setCancelable(false)
      progressDialog
    }
  }

}

import AndroidContext._
this.toast(msg)
this.progress().show()

Kotlin

fun Activity.toast(message: CharSequence?, duration: Int = Toast.LENGTH_SHORT) {
    Toast.makeText(this, message, duration).show()
}

fun Activity.progress() = ProgressDialog(this).apply {
    setProgressStyle(ProgressDialog.STYLE_SPINNER)
    setCancelable(false)
}

Switch

Java

String result;
switch (obj) {
    case 1:
        result = "Result is 1";
        break;
    case 10:
        result = "Result is 10";
        break;
    default:
        result = "Default result";
        break;
}

Groovy

def result
switch (obj) {
    case 0:
        result = "Object equals"
        break
    case 11..20:
        result = "Range contains"
        break
    case [1, 2, 3]:
        result = "List contains"
        break
    case Float:
        result = "Class instance"
        break
    case { it % 3 == 0 }:
        result = "Closure"
        break
    case ~'[0-9]{3}':
        result = "Pattern match"
        break
    default:
        result = "Default"
        break
}

Scala

val result = foo match {
  case 0 => "Object equals"
  case i if i == 10 || i == 11 => "Expression"
  case i: Int => s"Class instance holds $i"
  case List(1, 2, _*) => "List contains"
  case Number(n) => s"Case class holds $n"
  case t: {def length: Int} => "Duck type"
  case _ => "Default"
}

Kotlin

var result = when (foo) {
    0 -> "Object equals"
    3, 10 -> "Or"
    in 11..20 -> "Range contains"
    is Date -> "Class instance"
    !in 4..30 -> "Range not contain"
    else -> "Default"
}

3rd Party Libraries

Scala

• Scaloid

Kotlin

• Anko

Who use these languages?

TODO

Community Support

• Java Native Support
• Groovy Official Support
• Scala No Support
• Kotlin Official Support

Conclusion

The futher comparison to be continue...