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Annotation Processing Jake Wharton Boilerplate Destruction!

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Annotation Processing Jake Wharton Boilerplate Destruction!

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Dagger

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Dagger class CoffeeMaker {
 @Inject Lazy heater;
 @Inject Pump pump;
 
 public void brew() {
 heater.get().on();
 pump.pump();
 System.out.println(" [_]P coffee! [_]P ");
 heater.get().off();
 }
 }
 square.github.io/dagger/

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Butter Knife

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Butter Knife class SimpleActivity extends Activity {
 @InjectView(R.id.title) TextView title;
 @InjectView(R.id.subtitle) TextView subtitle;
 @InjectView(R.id.hello) Button hello;
 @InjectView(R.id.list_of_things) ListView listOfThings;
 @InjectView(R.id.footer) TextView footer;
 
 // ...
 } jakewharton.github.io/butterknife/

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Butter Knife class SimpleActivity extends Activity {
 @InjectView(R.id.title) TextView title;
 @InjectView(R.id.subtitle) TextView subtitle;
 @InjectView(R.id.hello) Button hello;
 @InjectView(R.id.list_of_things) ListView listOfThings;
 @InjectView(R.id.footer) TextView footer;
 
 // ...
 } jakewharton.github.io/butterknife/ ButterKnife.inject(this);

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AutoValue

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AutoValue @AutoValue
 abstract static class Animal {
 static Animal create(String name, int numberOfLegs) {
 return new AutoValue_Animal(name, numberOfLegs);
 } 
 abstract String name();
 abstract int numberOfLegs();
 }
 github.com/google/auto/

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AutoParcel

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AutoParcel @AutoParcel
 abstract class SomeModel implements Parcelable {
 abstract String name();
 abstract List subModels();
 abstract Map modelsMap();
 
 static SomeModel create(String name, List subModels, Map modelsMap) {
 return new AutoParcel_SomeModel(name, subModels, modelsMap);
 }
 } github.com/frankiesardo/auto-parcel/

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Schematic

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Schematic interface NoteColumns {
 
 @DataType(INTEGER) @PrimaryKey @AutoIncrement
 String _ID = "_id";
 
 @DataType(INTEGER) @References(table = NotesDatabase.LISTS,
 column = ListColumns._ID)
 String LIST_ID = "listId";
 
 @DataType(TEXT) String NOTE = "note";
 }

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Schematic @Database(version = NotesDatabase.VERSION)
 public final class NotesDatabase {
 
 public static final int VERSION = 1;
 
 @Table(ListColumns.class)
 public static final String LISTS = "lists";
 
 @Table(NoteColumns.class)
 public static final String NOTES = "notes";
 
 }

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Schematic @ContentProvider(authority = NotesProvider.AUTHORITY,
 database = NotesDatabase.class)
 public final class NotesProvider {
 // ...
 } github.com/SimonVT/schematic

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Doclet http://docs.oracle.com/javase/8/docs/technotes/guides/javadoc/doclet/overview.html

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Doclet import com.sun.javadoc.*; ! public class ExampleDoclet {
 public static boolean start(RootDoc root) {
 ! ! ! 
 }
 } http://docs.oracle.com/javase/8/docs/technotes/guides/javadoc/doclet/overview.html

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Doclet import com.sun.javadoc.*; ! public class ExampleDoclet {
 public static boolean start(RootDoc root) {
 ! ! ! 
 }
 } import com.sun.javadoc.*; ! public class ExampleDoclet {
 public static boolean start(RootDoc root) {
 ClassDoc[] classes = root.classes();
 for (int i = 0; i < classes.length; i++) {
 System.out.println(classes[i]);
 }
 return true; 
 }
 } http://docs.oracle.com/javase/8/docs/technotes/guides/javadoc/doclet/overview.html

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Doclet import com.sun.javadoc.*; ! public class ExampleDoclet {
 public static boolean start(RootDoc root) {
 ! ! ! 
 }
 } import com.sun.javadoc.*; ! public class ExampleDoclet {
 public static boolean start(RootDoc root) {
 ClassDoc[] classes = root.classes();
 for (int i = 0; i < classes.length; i++) {
 System.out.println(classes[i]);
 }
 return true; 
 }
 } javadoc -doclet ExampleDoclet -docletpath . RandomClass.java \
 FooBarClass.java HelloClass.java WorldClass.java import com.sun.javadoc.*; ! public class ExampleDoclet {
 public static boolean start(RootDoc root) {
 ClassDoc[] classes = root.classes();
 for (int i = 0; i < classes.length; i++) {
 System.out.println(classes[i]);
 }
 return true; 
 }
 } http://docs.oracle.com/javase/8/docs/technotes/guides/javadoc/doclet/overview.html

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Java 1.5

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Java 1.5

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Java 1.5 • JSR 14: Generics

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Java 1.5 • JSR 14: Generics • JSR 175: Annotations

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Java 1.5 • JSR 14: Generics • JSR 175: Annotations • Also a whole bunch of other really awesome things!

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Java 1.5 • JSR 14: Generics • JSR 175: Annotations • Also a whole bunch of other really awesome things! • apt command-line tool

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Annotation Processing Tool: apt apt

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apt

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@Target(ElementType.TYPE)
 public @interface Example {
 } apt

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@Target(ElementType.TYPE)
 public @interface Example {
 } @Example
 public class RandomClass {
 // ...
 } @Example
 public class FooBarClass {
 // ...
 } @Example
 public class HelloClass {
 // ...
 } @Example
 public class WorldClass {
 // ...
 } @Target(ElementType.TYPE)
 public @interface Example {
 } apt

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interface AnnotationProcessor {
 void process();
 } apt

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interface AnnotationProcessorFactory { 
 AnnotationProcessor getProcessorFor( Set atds, AnnotationProcessorEnvironment env); 
 Collection supportedAnnotationTypes(); 
 Collection supportedOptions(); 
 } interface AnnotationProcessor {
 void process();
 } apt

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apt public class ExampleAnnotationProcessorFactory implements AnnotationProcessorFactory { 
 
 
 
 
 
 
 
 
 
 
 
 
 }

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apt public class ExampleAnnotationProcessorFactory implements AnnotationProcessorFactory { 
 
 
 
 
 
 
 
 
 
 @Override public Collection supportedOptions() {
 return Collections.emptyList();
 }
 }

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apt public class ExampleAnnotationProcessorFactory implements AnnotationProcessorFactory { 
 
 
 
 
 
 @Override public Collection supportedAnnotationTypes() {
 return Collections.singletonList(Example.class.getName());
 }
 
 @Override public Collection supportedOptions() {
 return Collections.emptyList();
 }
 }

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apt public class ExampleAnnotationProcessorFactory implements AnnotationProcessorFactory { 
 @Override public AnnotationProcessor getProcessorFor( Set atds,
 AnnotationProcessorEnvironment env) {
 return new ExampleAnnotationProcessor(atds, env);
 }
 
 @Override public Collection supportedAnnotationTypes() {
 return Collections.singletonList(Example.class.getName());
 }
 
 @Override public Collection supportedOptions() {
 return Collections.emptyList();
 }
 }

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apt public class ExampleAnnotationProcessorFactory implements AnnotationProcessorFactory { 
 @Override public AnnotationProcessor getProcessorFor( Set atds,
 AnnotationProcessorEnvironment env) {
 return new ExampleAnnotationProcessor(atds, env);
 }
 
 @Override public Collection supportedAnnotationTypes() {
 return Collections.singletonList(Example.class.getName());
 }
 
 @Override public Collection supportedOptions() {
 return Collections.emptyList();
 }
 }

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apt public class ExampleAnnotationProcessor implements AnnotationProcessor { 
 
 
 
 
 
 
 
 
 }

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apt public class 
 
 
 
 
 
 
 
 
 } public class ExampleAnnotationProcessor implements AnnotationProcessor { 
 private final Set atds;
 private final AnnotationProcessorEnvironment env;
 
 public ExampleAnnotationProcessor( Set atds,
 AnnotationProcessorEnvironment env) {
 this.atds = atds;
 this.env = env;
 } 
 }

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apt public class 
 
 
 
 
 
 
 
 
 } public class 
 
 Set atds 
 } public class ExampleAnnotationProcessor implements AnnotationProcessor { 
 
 
 
 
 
 
 
 
 } public class ExampleAnnotationProcessor implements AnnotationProcessor { 
 // ...
 
 
 
 
 
 
 
 } public class ExampleAnnotationProcessor implements AnnotationProcessor { 
 // ...
 
 @Override public void process() {
 ! ! 
 } ! 
 }

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apt public class 
 
 
 
 
 
 
 
 
 } public class 
 
 Set atds 
 } public class ExampleAnnotationProcessor implements AnnotationProcessor { 
 
 
 
 
 
 
 
 
 } public class ExampleAnnotationProcessor implements AnnotationProcessor { 
 // ...
 
 
 
 
 
 
 
 } public class ExampleAnnotationProcessor implements AnnotationProcessor { 
 // ...
 
 @Override public void process() { for (AnnotationTypeDeclaration atd : atds) {
 MemberDeclaration member = atd.getDeclaringType();
 System.out.println(member);
 }
 } ! ! }

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apt apt -classpath out/ src/RandomClass.java \
 src/FooBarClass.java src/HelloClass.java \
 src/WorldClass.java http://docs.oracle.com/javase/1.5.0/docs/tooldocs/share/apt.html

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JSR 269

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JSR 269 • 6 months after Java 5 released

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JSR 269 • 6 months after Java 5 released • “Pluggable Annotation Processing API”

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JSR 269 • 6 months after Java 5 released • “Pluggable Annotation Processing API” • Google, Oracle, Sun, BEA Systems sponsored

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JSR 269 • 6 months after Java 5 released • “Pluggable Annotation Processing API” • Google, Oracle, Sun, BEA Systems sponsored • Simplify and standardize processing annotations

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JSR 269 • 6 months after Java 5 released • “Pluggable Annotation Processing API” • Google, Oracle, Sun, BEA Systems sponsored • Simplify and standardize processing annotations • No standalone tool, part of javac

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interface AnnotationProcessor {
 void process();
 }

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interface Processor {
 Set getSupportedOptions();
 
 Set getSupportedAnnotationTypes();
 
 SourceVersion getSupportedSourceVersion();
 
 void init(ProcessingEnvironment processingEnv);
 
 boolean process(Set extends TypeElement> annotations,
 RoundEnvironment roundEnv);
 
 Iterable extends Completion> getCompletions(Element element,
 AnnotationMirror annotation,
 ExecutableElement member,
 String userText);
 }

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public class ExampleProcessor extends AbstractProcessor {
 
 
 
 
 
 
 
 
 
 
 
 
 
 }

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public class ExampleProcessor extends AbstractProcessor {
 @Override public SourceVersion getSupportedSourceVersion() {
 
 }
 
 
 
 
 
 
 
 
 
 
 }

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public class ExampleProcessor extends AbstractProcessor {
 @Override public SourceVersion getSupportedSourceVersion() {
 return SourceVersion.latestSupported();
 }
 
 
 
 
 
 
 
 
 
 
 }

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public class ExampleProcessor extends AbstractProcessor {
 @Override public SourceVersion getSupportedSourceVersion() {
 return SourceVersion.latestSupported();
 }
 
 @Override public Set getSupportedAnnotationTypes() {
 
 }
 
 
 
 
 
 
 }

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public class ExampleProcessor extends AbstractProcessor {
 @Override public SourceVersion getSupportedSourceVersion() {
 return SourceVersion.latestSupported();
 }
 
 @Override public Set getSupportedAnnotationTypes() {
 return Collections.singleton(Example.class.getName());
 }
 
 
 
 
 
 
 }

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public class ExampleProcessor extends AbstractProcessor {
 @Override public SourceVersion getSupportedSourceVersion() {
 return SourceVersion.latestSupported();
 }
 
 @Override public Set getSupportedAnnotationTypes() {
 return Collections.singleton(Example.class.getName());
 }
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 
 }
 }

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public class ExampleProcessor extends AbstractProcessor {
 // ...
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 ! ! ! ! ! 
 }
 }

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public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 
 
 
 
 
 }
 }

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public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element);
 }
 
 
 }
 }

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public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element);
 }
 
 return false;
 }
 }

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public class ExampleProcessor extends AbstractProcessor {
 @Override public SourceVersion getSupportedSourceVersion() {
 return SourceVersion.latestSupported();
 }
 
 @Override public Set getSupportedAnnotationTypes() {
 return Collections.singleton(Example.class.getName());
 }
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element);
 }
 return false;
 }
 }

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Execution

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Execution • Happens automatically when javac runs.

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Execution • Happens automatically when javac runs. • ServiceLoader finds and creates Processor instances.

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Service Loader

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Service Loader • META-­‐INF/services/

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Service Loader • META-­‐INF/services/ • File name of implemented fully-qualified class name.

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Service Loader • META-­‐INF/services/ • File name of implemented fully-qualified class name. • javax.annotation.processing.Processor

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Service Loader • META-­‐INF/services/ • File name of implemented fully-qualified class name. • javax.annotation.processing.Processor • Each line implementation fully-qualified class name.

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Service Loader • META-­‐INF/services/ • File name of implemented fully-qualified class name. • javax.annotation.processing.Processor • Each line implementation fully-qualified class name. • com.example.ExampleProcessor

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Execution • Happens automatically when javac runs. • ServiceLoader finds and creates Processor instances.

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Execution • Happens automatically when javac runs. • ServiceLoader finds and creates Processor instances. • Inside a full JVM.

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Execution • Happens automatically when javac runs. • ServiceLoader finds and creates Processor instances. • Inside a full JVM. • Compiled sources and its dependencies not available.

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Execution • Happens automatically when javac runs. • ServiceLoader finds and creates Processor instances. • Inside a full JVM. • Compiled sources and its dependencies not available. • Bring your own dependencies.

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Environment

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Environment interface Processor {
 Set getSupportedOptions();
 
 Set getSupportedAnnotationTypes();
 
 SourceVersion getSupportedSourceVersion();
 
 void init(ProcessingEnvironment processingEnv);
 
 boolean process(Set extends TypeElement> annotations,
 RoundEnvironment roundEnv);
 
 Iterable extends Completion> getCompletions(Element element,
 AnnotationMirror annotation,
 ExecutableElement member,
 String userText);
 }

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Environment interface Processor {
 Set getSupportedOptions();
 
 Set getSupportedAnnotationTypes();
 
 SourceVersion getSupportedSourceVersion();
 
 void init(ProcessingEnvironment processingEnv);
 
 boolean process(Set extends TypeElement> annotations,
 RoundEnvironment roundEnv);
 
 Iterable extends Completion> getCompletions(Element element,
 AnnotationMirror annotation,
 ExecutableElement member,
 String userText);
 }

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Environment interface Processor {
 Set getSupportedOptions();
 
 Set getSupportedAnnotationTypes();
 
 SourceVersion getSupportedSourceVersion();
 
 void init(ProcessingEnvironment processingEnv);
 
 boolean process(Set extends TypeElement> annotations,
 RoundEnvironment roundEnv);
 
 Iterable extends Completion> getCompletions(Element element,
 AnnotationMirror annotation,
 ExecutableElement member,
 String userText);
 }

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Environment interface Processor {
 Set getSupportedOptions();
 
 Set getSupportedAnnotationTypes();
 
 SourceVersion getSupportedSourceVersion();
 
 void init(ProcessingEnvironment processingEnv);
 
 boolean process(Set extends TypeElement> annotations,
 RoundEnvironment roundEnv);
 
 Iterable extends Completion> getCompletions(Element element,
 AnnotationMirror annotation,
 ExecutableElement member,
 String userText);
 }

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Environment interface Processor {
 Set getSupportedOptions();
 
 Set getSupportedAnnotationTypes();
 
 SourceVersion getSupportedSourceVersion();
 
 void init(ProcessingEnvironment processingEnv);
 
 boolean process(Set extends TypeElement> annotations,
 RoundEnvironment roundEnv);
 
 Iterable extends Completion> getCompletions(Element element,
 AnnotationMirror annotation,
 ExecutableElement member,
 String userText);
 }

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Processing Environment

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Processing Environment interface ProcessingEnvironment {
 Map getOptions(); 
 SourceVersion getSourceVersion();
 
 Locale getLocale();
 
 Messager getMessager();
 
 Filer getFiler();
 
 Elements getElementUtils();
 
 Types getTypeUtils();
 }

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Processing Environment interface ProcessingEnvironment {
 Map getOptions(); 
 SourceVersion getSourceVersion();
 
 Locale getLocale();
 
 Messager getMessager();
 
 Filer getFiler();
 
 Elements getElementUtils();
 
 Types getTypeUtils();
 }

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Processing Environment interface ProcessingEnvironment {
 Map getOptions(); 
 SourceVersion getSourceVersion();
 
 Locale getLocale();
 
 Messager getMessager();
 
 Filer getFiler();
 
 Elements getElementUtils();
 
 Types getTypeUtils();
 }

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Processing Environment interface ProcessingEnvironment {
 Map getOptions(); 
 SourceVersion getSourceVersion();
 
 Locale getLocale();
 
 Messager getMessager();
 
 Filer getFiler();
 
 Elements getElementUtils();
 
 Types getTypeUtils();
 }

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Processing Environment interface ProcessingEnvironment {
 Map getOptions(); 
 SourceVersion getSourceVersion();
 
 Locale getLocale();
 
 Messager getMessager();
 
 Filer getFiler();
 
 Elements getElementUtils();
 
 Types getTypeUtils();
 }

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Elements

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Elements @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 }

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Elements @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 } TypeElement

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Elements @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 } TypeElement VariableElement

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Elements @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 } TypeElement VariableElement ExecutableElement

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Elements @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 } TypeElement VariableElement ExecutableElement ExecutableElement

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Elements @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 } TypeElement VariableElement ExecutableElement ExecutableElement

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Elements @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 } TypeElement VariableElement ExecutableElement ExecutableElement

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Types @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 }

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Types @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 }

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Types @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 }

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Types @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 }

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Types @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 }

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Types @Example
 public class ExampleClass implements Runnable { 
 private final String name;
 
 public ExampleClass(String name) {
 this.name = name;
 }
 
 @Override public void run() {
 System.out.println("Hello, " + name);
 }
 }

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Environment

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Environment public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element
 }
 return false;
 }
 } 
 
 
 
 
 
 
 
 
 );
 
 
 


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Environment public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element
 }
 return false;
 }
 } 
 
 
 
 
 
 
 
 
 );
 
 
 


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Environment public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println( );
 }
 return false;
 }
 } 
 
 
 
 
 
 
 
 
 element.asType()
 
 
 


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Environment public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element.asType());
 }
 return false;
 }
 }

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Environment public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element.asType());
 }
 return false;
 }
 }

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Environment public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element.asType());
 }
 return false;
 }
 }

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Round Environment

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Round Environment public interface RoundEnvironment {
 boolean processingOver();
 
 boolean errorRaised();
 
 Set extends Element> getRootElements();
 
 Set extends Element> getElementsAnnotatedWith(
 TypeElement a);
 
 Set extends Element> getElementsAnnotatedWith(
 Class extends Annotation> a);
 }

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Round Environment public interface RoundEnvironment {
 boolean processingOver();
 
 boolean errorRaised();
 
 Set extends Element> getRootElements();
 
 Set extends Element> getElementsAnnotatedWith(
 TypeElement a);
 
 Set extends Element> getElementsAnnotatedWith(
 Class extends Annotation> a);
 }

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Processing Rounds

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Processing Rounds @Example
 public class RandomClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Example
 public class RandomClass {
 // ...
 } javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Example
 public class RandomClass {
 // ...
 } javac ExampleProcessor

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } @Example
 public class RandomClass {
 // ...
 } javac ExampleProcessor

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } @Example
 public class RandomClass {
 // ...
 } javac OtherProcessor

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } @Example
 public class RandomClass {
 // ...
 } javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } @Example
 public class RandomClass {
 // ...
 } javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } @Example
 public class RandomClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } @Example
 public class RandomClass {
 // ...
 } javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } @Example
 public class RandomClass {
 // ...
 } javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac ExampleProcessor

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac OtherProcessor

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac OtherProcessor public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac public class OtherGenClass {
 // ...
 } OtherGenClass.class public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac public class OtherGenClass {
 // ...
 } ExampleProcessor OtherGenClass.class public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac public class OtherGenClass {
 // ...
 } OtherProcessor OtherGenClass.class public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac public class OtherGenClass {
 // ...
 } OtherGenClass.class public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } javac public class OtherGenClass {
 // ...
 } OtherGenClass.class public class OtherGenClass {
 // ...
 }

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Processing Rounds @Example
 public class RandomClass {
 // ...
 } ExampleProcessor OtherProcessor javac RandomClass.class out/ @Other
 public class GeneratedClass {
 // ...
 } GeneratedClass.class @Example
 public class RandomClass {
 // ...
 } @Other
 public class GeneratedClass {
 // ...
 } public class OtherGenClass {
 // ...
 } OtherGenClass.class public class OtherGenClass {
 // ...
 }

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JavaCompiler

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ExampleProcessor JavaCompiler OtherProcessor

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ProcessingEnvironment ExampleProcessor JavaCompiler Filer OtherProcessor

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ProcessingEnvironment ExampleProcessor JavaCompiler Filer OtherProcessor init() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler Filer OtherProcessor init() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler Filer OtherProcessor init() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init() process()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init() process()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init() process()

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ProcessingEnvironment ExampleProcessor JavaCompiler RoundEnvironment Filer OtherProcessor init() process() init() process()

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Parsing and Generation

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Parsing and Generation public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 
 for (Element element : elements) {
 
 
 }
 return false;
 }
 }

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Parsing and Generation public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 
 for (Element element : elements) {
 
 
 }
 return false;
 }
 } 
 
 
 
 
 
 
 
 
 // Look at attributes of 'element'.
 
 
 
 


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Parsing and Generation public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 
 for (Element element : elements) {
 
 
 }
 return false;
 }
 } 
 
 
 
 
 
 
 
 
 // Look at attributes of 'element'.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 // Generate some code based on attributes.
 
 
 


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Parsing and Generation

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Parsing and Generation @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 
 
 
 
 return false;
 }


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Parsing and Generation @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 
 
 
 
 return false;
 }
 
 
 
 List models = parseExampleAnnotations(env);

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Parsing and Generation @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 
 
 
 
 return false;
 }
 
 
 
 List models = parseExampleAnnotations(env); 
 
 
 
 
 
 
 
 
 
 List parseExampleAnnotations(RoundEnvironment env) {
 // ...
 }

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Parsing and Generation @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 
 
 
 
 return false;
 }
 
 
 
 List models = parseExampleAnnotations(env); 
 
 
 
 for (ExampleModel model : models) {
 emitExampleCode(model);
 } 
 
 
 
 
 
 
 
 
 
 List parseExampleAnnotations(RoundEnvironment env) {
 // ...
 }

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Parsing and Generation @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 
 
 
 
 return false;
 }
 
 
 
 List models = parseExampleAnnotations(env); 
 
 
 
 for (ExampleModel model : models) {
 emitExampleCode(model);
 } 
 
 
 
 
 
 
 
 
 
 List parseExampleAnnotations(RoundEnvironment env) {
 // ...
 } 
 
 
 
 
 
 
 
 
 ! ! 
 
 void emitExampleCode(ExampleModel model) {
 // ...
 }

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Parsing and Generation

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Parsing and Generation Element

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Parsing and Generation Element

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Parsing and Generation Element ExampleModel ! name: “Foo” package: “com.example” public: true

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Parsing and Generation Element ExampleModel ! name: “Foo” package: “com.example” public: true

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Parsing and Generation Element ExampleModel ! name: “Foo” package: “com.example” public: true ExampleModel ! name: “Foo” package: “com.example” public: true element:

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Parsing and Generation Element ExampleModel ! name: “Foo” package: “com.example” public: true ExampleModel ! name: “Foo” package: “com.example” public: true element: GeneratedClass

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Parsing and Generation Element ExampleModel ! name: “Foo” package: “com.example” public: true ExampleModel ! name: “Foo” package: “com.example” public: true element: GeneratedClass

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Bring Your Own Dependencies

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Bring Your Own Dependencies • Guava, Guava, Guava!

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Bring Your Own Dependencies • Guava, Guava, Guava! • JavaWriter

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Bring Your Own Dependencies • Guava, Guava, Guava! • JavaWriter • google/auto ‘common’

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Bring Your Own Dependencies • Guava, Guava, Guava! • JavaWriter • google/auto ‘common’ • AutoService (google/auto)

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JavaWriter

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JavaWriter JavaFileObject sourceFile = filer.createSourceFile(name, element);

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JavaWriter JavaFileObject sourceFile = filer.createSourceFile(name, element); ! ! ! JavaWriter writer = new JavaWriter(sourceFile.openWriter());
 writer.emitPackage("com.example")
 .emitAnnotation(Other.class)
 .beginType("GeneratedClass", "class")
 .emitSingleLineComment("...")
 .endType();

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JavaWriter JavaFileObject sourceFile = filer.createSourceFile(name, element); ! ! @com.example.Other
 public class GeneratedClass {
 // ...
 } ! ! ! JavaWriter writer = new JavaWriter(sourceFile.openWriter());
 writer.emitPackage("com.example")
 .emitAnnotation(Other.class)
 .beginType("GeneratedClass", "class")
 .emitSingleLineComment("...")
 .endType();

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JavaWriter JavaFileObject sourceFile = filer.createSourceFile(name, element); import com.example.Other; ! @Other
 public class GeneratedClass {
 // ...
 } ! ! ! JavaWriter writer = new JavaWriter(sourceFile.openWriter());
 writer.emitPackage("com.example")
 .emitImports(Other.class)
 .emitAnnotation(Other.class)
 .beginType("GeneratedClass", "class")
 .emitSingleLineComment("...")
 .endType(); JavaFileObject sourceFile = filer.createSourceFile(name, element);

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AutoService

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AutoService • Remember?
 META-­‐INF/services/javax.annotation.processing.Processor

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AutoService • Remember?
 META-­‐INF/services/javax.annotation.processing.Processor • AutoService generates service files from annotations

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AutoService • Remember?
 META-­‐INF/services/javax.annotation.processing.Processor • AutoService generates service files from annotations ! public class ExampleProcessor extends AbstractProcessor { // ... }

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AutoService • Remember?
 META-­‐INF/services/javax.annotation.processing.Processor • AutoService generates service files from annotations ! public class ExampleProcessor extends AbstractProcessor { // ... } @AutoService(Processor.class)

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Testing and Debugging

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Testing and Debugging • Google to the rescue!

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Testing and Debugging • Google to the rescue! • Guava

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Testing and Debugging • Google to the rescue! • Guava • Guava

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Testing and Debugging • Google to the rescue! • Guava • Guava • compile-testing

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Testing and Debugging • Google to the rescue! • Guava • Guava • compile-testing • Truth

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final class TestProcessors {
 static Iterable extends Processor> exampleProcessors() {
 return Collections.singletonList(
 new ExampleProcessor()
 );
 }
 }

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String input = Joiner.on('\n').join(
 "package test;",
 "import com.example.Example;",
 "@Example",
 "public class ExampleClass {",
 "}"
 );

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String input = Joiner.on('\n').join(
 "package test;",
 "import com.example.Example;",
 "@Example",
 "public class ExampleClass {",
 "}"
 ); JavaFileObject inputFile =
 JavaFileObjects.forSourceString("test.Test", input);

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JavaFileObject inputFile =
 JavaFileObjects.forSourceString("test.Test", input); String input = """\
 package test; 
 import com.example.Example; 
 @Example
 public class ExampleClass {
 } """ .stripIndent()

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String expected = Joiner.on('\n').join(
 "package test;",
 "import com.example.Other;",
 "@Other",
 "public class GeneratedClass {",
 "}"
 );

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String expected = Joiner.on('\n').join(
 "package test;",
 "import com.example.Other;",
 "@Other",
 "public class GeneratedClass {",
 "}"
 ); JavaFileObject expectedFile =
 JavaFileObjects.forSourceString("test.GeneratedClass", expected);

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ASSERT.about(javaSource())
 .that(inputFile)
 .processedWith(exampleProcessors())
 .compilesWithoutError()
 .and()
 .generatesSources(expectedFile);

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ASSERT.about(javaSource())
 .that(inputFile)
 .processedWith(exampleProcessors())
 .compilesWithoutError()
 .and()
 .generatesSources(expectedFile);

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ASSERT.about(javaSource())
 .that(inputFile)
 .processedWith(exampleProcessors())
 .compilesWithoutError()
 .and()
 .generatesSources(expectedFile);

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ASSERT.about(javaSource())
 .that(inputFile)
 .processedWith(exampleProcessors())
 .compilesWithoutError()
 .and()
 .generatesSources(expectedFile); String input = Joiner.on('\n').join(
 "package test;",
 "import com.example.Example;",
 "@Example",
 "public class ExampleClass {",
 "}"
 );

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ASSERT.about(javaSource())
 .that(inputFile)
 .processedWith(exampleProcessors())
 .compilesWithoutError()
 .and()
 .generatesSources(expectedFile); String input = Joiner.on('\n').join(
 "package test;",
 "import com.example.Example;",
 "@Example",
 "public class ExampleClass {",
 "}"
 ); final class TestProcessors {
 static Iterable extends Processor> exampleProcessors() {
 return Collections.singletonList(
 new ExampleProcessor()
 );
 }
 }

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ASSERT.about(javaSource())
 .that(inputFile)
 .processedWith(exampleProcessors())
 .compilesWithoutError()
 .and()
 .generatesSources(expectedFile); String input = Joiner.on('\n').join(
 "package test;",
 "import com.example.Example;",
 "@Example",
 "public class ExampleClass {",
 "}"
 ); final class TestProcessors {
 static Iterable extends Processor> exampleProcessors() {
 return Collections.singletonList(
 new ExampleProcessor()
 );
 }
 } String expected = Joiner.on('\n').join(
 "package test;",
 "import com.example.Other;",
 "@Other",
 "public class GeneratedClass {",
 "}"
 );

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ASSERT.about(javaSource())
 .that(inputFile)
 .processedWith(exampleProcessors())
 .compilesWithoutError()
 .and()
 .generatesSources(expectedFile); String input = Joiner.on('\n').join(
 "package test;",
 "import com.example.Example;",
 "@Example",
 "public class ExampleClass {",
 "}"
 ); final class TestProcessors {
 static Iterable extends Processor> exampleProcessors() {
 return Collections.singletonList(
 new ExampleProcessor()
 );
 }
 } String expected = Joiner.on('\n').join(
 "package test;",
 "import com.example.Other;",
 "@Other",
 "public class GeneratedClass {",
 "}"
 );

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Debugging

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public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element
 }
 return false;
 }
 } Debugging

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public class ExampleProcessor extends AbstractProcessor {
 // ...
 
 @Override public boolean process(
 Set extends TypeElement> annotations,
 RoundEnvironment env) {
 Set extends Element> elements
 = env.getElementsAnnotatedWith(Example.class);
 for (Element element : elements) {
 System.out.println(element
 }
 return false;
 }
 } Debugging

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Now What?

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Questions?