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Annotation processing
Annotation processing allows generating new Java files at build time from annotations without using reflection. It was introduced in Java 5 and lets you write processors to handle annotations. For Android, the android-apt Gradle plugin is needed to support annotation processing. A processor class extends AbstractProcessor and contains processing logic in the process() method to handle annotations and generate files. Examples generate getters automatically from fields or convert POJOs to strings.
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Annotation processing
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- 2. ANNOTATION PROCESSING A BITOF HISTORY ▸ Were first introduced in Java Language with the third edition of the Java Language Specification (JLS) ▸ And introduced in Java 5
- 3. ANNOTATION PROCESSING WHAT IS? ▸Annotation processing lets you generate new Java files at build time. ▸ There is no need to use reflection. Although the generated Java files can use reflection, if you wish. ▸ Just cause performance degradation on build time.
- 4. ANNOTATION PROCESSING HOW CANI DO ▸ Android Studio doesn’t have build in support for annotation processing. ▸ You need to use the android-apt Gradle plugin for your compile code as build time dependency without including it in the final apk.
- 5. ANNOTATION PROCESSING ▸ First:In your project's build.gradle you should use ▸ Second: Create a module Compiler ▸ Third: App’s build.gradle
- 6. ANNOTATION PROCESSING ▸ Finally:The compiler’s build.gradle ▸ plugin java instead plugin android. After all, this code going to run on the machine. Note on an Android.
- 7. ANNOTATION PROCESSING ABSTRACT PROCESSOR ▸AbstractProcessor. Let’s have a look at the Processor API.
- 8. ANNOTATION PROCESSING THE PROCESSORIT SELF ▸ void init (ProcessingEnvironment) ▸ All annotation processor must have a empty constructor! ▸ This is special init() which is invoked by the annotation processing tool
- 9. ANNOTATION PROCESSING THE PROCESSORIT SELF ▸ boolean process(Set<? extends TypeElement> annotations, RoundEnvironment env) ▸ This is kind of main() method of each processor ▸ Here you write code for spanning, processing annotation and generating java files.
- 10. ANNOTATION PROCESSING LIVE CODE ▸Let’s generate automatic getter for our fields.
- 11. ANNOTATION PROCESSING OK, SHOWME EXEMPLES MUCH MORE…
- 12. ANNOTATION PROCESSING ABOUT ME ▸Felipe Theodoro Gonçalves Android Developer at Elo7 @ftgoncalves ftgoncalves@gmail.com ▸ Slack Android Dev BR / Android Study Group http://brianattwell.com/android-annotation- processing-pojo-string-generator/ http://hannesdorfmann.com/annotation- processing/annotationprocessing101 Referências