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

Only import the minimal dependencies.

• In Java
  • Import com.android.support:appcompat-v7:23.1.1
• In Groovy
  • Import com.android.support:appcompat-v7:23.1.1
  • Import org.codehaus.groovy:groovy:2.4.5:grooid
  • Import org.codehaus.groovy:groovy-json:2.4.5
• In Scala
  • Import com.android.support:appcompat-v7:23.1.1
  • Import org.scala-lang:scala-library:2.11.7
  • Import org.scaloid:scaloid_2.11:4.0
• In Kotlin
  • Import com.android.support:appcompat-v7:23.1.1
  • Import org.jetbrains.kotlin:kotlin-stdlib:1.0.0-beta-4584

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Java

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

Groovy

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

Scala

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

Kotlin

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

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
}

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
}

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

The futher comparasion to be continue...