liaohuijun/AndroidDemoIn4Languages

Comparison among Java, Groovy, Scala, Kotlin in Android Development.

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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

Language	Files	Blank Lines	Comment Lines	Code Lines
Java	3	20	9	157
Groovy	3	23	9	140
Scala	3	32	9	127
Kotlin	3	23	9	136

Size Counter

Language	Disable Proguard (bytes)	Enable Proguard (bytes)
Java	1,438,673	893,137
Groovy	3,395,936	1,982,125
Scala	3,277,007	1,349,352
Kotlin	1,833,258	903,566

Method Counter

Language	Disable Proguard	Enable Proguard
Java	17,416	7,608
Groovy	47,982	24,379
Scala	67,608	20,109
Kotlin	23,587	7,656

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

Language	Gradle Plugin	Time (secs)	SBT	Time (secs)
Java	2.2.0	≈ 8	0.13.12	≈ 10
Groovy	2.2.0	≈ 20	0.13.12	-
Scala	1.3.1	≈ 28	0.13.12	≈ 17
Kotlin	2.2.0	≈ 9	0.13.12	≈ 20

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...