This document discusses using Groovy on Android apps. Groovy is a JVM language that offers simplicity compared to Java and interoperability. To use Groovy in an Android project, the Groovy and Grooid dependencies are added along with plugins. Groovy classes can then be created alongside Java sources. Benefits include collections APIs, AST transformations for domain objects, and libraries like Fluent and SwissKnife. Potential downsides are issues with Android Studio integration and large APK sizes.

1. Groovy on Android
(as of 2016)

2. About Me
Kevin H.A. Tan
Solutions Evangelist
Polyglot Software Dev
AWPL.co

3. My Tech Stacks
• Android, Spring Boot, AngularJS, Java in
general, Groovy related frameworks like Gaelyk
and Grails, etc.

4. About Android
• mobile operating system based on Dalvik and
ART, coded in Java

5. About Groovy
• JVM programming language that has been
existent since 2004

6. About Groovy

7. Why Groovy?
• Simplicity compared to Java Syntax
• Reactive (sorta)
• Interoperability with Java code

8. Differences between
yesteryear and 2016
• groovy-all and grooid

9. Usage
buildscript{
repositories {
jcenter()
}
dependencies {
classpath ‘com.android.tools.build:gradle:1.5.0’
classpath ‘org.codehaus.groovy:gradle-groovy-android-plugin:
0.3.8’
}
}
apply plugin: ‘groovyx.grooid.groovy-android’

10. Usage
dependencies {
compile ‘org.codehaus.groovy:groovy:2.4.5:grooid’
}

11. Lazybones
• Project bootstrap
http://mariogarcia.github.io/grooid-templates/
lazybones create grooid-new-project newandroidproject

12. Lazybones

13. Project Structure
• src/main/groovy
• src/test/groovy
• src/androidTest/groovy

14. Source sets
androidGroovy {
sourceSets {
main {
groovy {
srcDirs += ‘src/main/java’
}
}
}
}

15. Compilation Options
androidGroovy {
options {
configure(groovyOptions) {
encoding = 'UTF-8'
forkOptions.jvmArgs = ['-noverify'] // maybe necessary if you
use Google Play Services
}
sourceCompatibility = '1.7' // as of 0.3.9 these are
automatically set based off the android plugin's
targetCompatibility = '1.7'
}
}

16. Domain Classes
• Groovy AST Transformation (AST means Abstract Syntax Tree,
which is basically an abstract representation of code / any
syntactic structure. A transformation is an action modifying this
tree)
@AutoExternalize
@ToString
@Immutable
@InheritConstructors

17. Domain Classes

18. Collections
userList.findAll { User user ->
user.isCompanyTeam
}.sort { User user ->
user.fullName
}

19. Prevent NPE
• ? operator
• * operator
responseList?.add(…)

20. Sample Activity

21. Libraries
• Fluent API
• JsonSlurper and XMLSlurper
• Groovy AST Transformation
• SwissKnife (similar with Butterknife by Jake Wharton)
More info: http://groovy-almanac.org/ and
http://melix.github.io/blog/2014/06/grooid.html

22. SwissKnife
https://github.com/Arasthel/SwissKnife
DSLs for example:
@OnUiThread
void doSomething(){
}

23. SwissKnife
SwissKnife.restoreState(saveInstanceState)

24. Downsides
• Doesn’t fully work with Android Studio in terms of
Goto File implementation (workaround - double
tap Shift to search and go to file)
• Right click on package, select New > Create
Groovy Class doesn’t appear.
• Packaged APK file is huge (due to the hug
grooid jar size)

25. Other than that…
• Almost everything works… almost

26. DEMO

27. References
Introduction to Groovy
• http://www.slideshare.net/L0rDKadaj/
introduction-to-groovy-39150312

28. • Contact me
http://about.me/kevintanhongann