A beginner's guide to annotation processing. In this talk that I gave at Droidcon Tel Aviv in 2016, I walk you through the process of building a custom annotation processor which mimics some of the behavior you may be familiar with from the popular Android library: Butter Knife.

1. Write code that writes code!
A beginner’s guide to annotation processing.

2. Obligatory Speaker Details
• Software Engineer for Bandcamp
• I’m from the US, but am living in Europe for now.
(working remotely)
• I have a dog named Watson. On weekends, we
walk across the Netherlands together.

3. Questions we ask ourselves in the
beginning.
• What is an annotation, and what is annotation
processing?
• Why would I want to process annotations?
• How do I make something cool? Maybe a
ButterKnife clone?

4. –http://docs.oracle.com/javase/1.5.0/docs/guide/language/annotations.html
“…an annotation is a form of syntactic
metadata…”
Annotations

5. –http://docs.oracle.com/javase/1.5.0/docs/guide/language/annotations.html
“Annotations do not directly affect program
semantics, but they do affect the way programs
are treated by tools and libraries, which can in
turn affect the semantics of the running
program.”
Annotations

6. Annotations
• You’ve seen them before (e.g. @Override, @Deprecated, etc.)
• They allow you to decorate code with information about the
code (ie: they are meta data)
• Kind of like comments, but they are more machine
readable than human readable.
• Annotations can be used by the JDK, third party libraries, or
custom tools.
• You can create your own annotations.

7. Custom annotations are
useless..
… until you use them.

8. Custom Annotations
• Useless

9. • Useless (until you actually use them…)
Custom Annotations
• Useless

10. • Useless
• Run-time - with reflection
• Compile-time “Annotation Processor”
• Useless (until you actually use them…)
Custom Annotations
• Useless

11. –Everyone
“Reflection is slow and you should never use it.”

12. –Smart People
“Reflection is slow and you should try to avoid
using it on the main thread.”

13. Annotation Processors
• Operate at build-time, rather than run-time.
• Are executed by the “annotation processing
tool” (apt)
• Must be part of a plain-old java library, without
direct dependencies on Android-specific stuff.
• Extend from
javax.annotation.processing.AbstractProcessor

14. Annotation Processing
List unprocessed
source files with
annotations.
Register
Annotation
Processors
Any
Processors
for them?
Run ProcessorsCompile
No* Yes

15. Annotation Processing
* If a processor was asked to process on a given round, it will be asked to process on
subsequent rounds, including the last round, even if there are no annotations for it to
process.
https://docs.oracle.com/javase/8/docs/api/javax/annotation/processing/Processor.html
List unprocessed
source files with
annotations.
Register
Annotation
Processors
Any
Processors
for them?
Run ProcessorsCompile
No* Yes

16. Why would you want to make one?
• Boilerplate Reduction
• Reducing Boilerplate
• Reduced Boilerplate
• ….
• It’s pretty cool.

17. Let’s make one.

18. “Soup Ladle”
• Wanted something that sounded like Butter
Knife, but was a different utensil.
• I like Soup.
• Ladles are big spoons.
• Big spoon = more soup in my face at once.

19. Soup Ladle Goals
• Allow for view binding with an annotation:
@Bind(R.id.some_id) View fieldName;
• Perform the binding easily using a one liner in
onCreate:
SoupLadle.bind(this);
• That’s it.. we are reinventing the wheel for
learning’s sake and don’t need to go all in.

20. Approach
1. Define the @Bind annotation.
2. Extend AbstractProcessor to create our
annotation processor for @Bind.
3. Within our processor: scan for all fields with
@Bind, keeping track of their parent classes.
4. Generate SoupLadle.java with .bind methods
for each parent class containing bound fields.

21. Approach
1. Define the @Bind annotation.
2. Extend AbstractProcessor to create our
annotation processor for @Bind.
3. Within our processor: scan for all fields with
@Bind, keeping track of their parent classes.
4. Generate SoupLadle.java with .bind methods
for each parent class containing bound fields.

22. Define @Bind
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.SOURCE)
public @interface Bind {
int value();
}

23. Define @Bind
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.SOURCE)
public @interface Bind {
int value();
}

24. Define @Bind
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.SOURCE)
public @interface Bind {
int value();
}

25. Define @Bind
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.SOURCE)
public @interface Bind {
int value();
}

26. Define @Bind
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.SOURCE)
public @interface Bind {
int value();
}

27. Approach
1. Define the @Bind annotation.
2. Extend AbstractProcessor to create our
annotation processor for @Bind.
3. Within our processor: scan for all fields with
@Bind, keeping track of their parent classes.
4. Generate SoupLadle.java with .bind methods
for each parent class containing bound fields.

28. Extending AbstractProcessor
public class AnnotationProcessor extends AbstractProcessor {
private Filer mFiler;
@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init(processingEnv);
mFiler = processingEnv.getFiler();
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public Set<String> getSupportedAnnotationTypes() {
HashSet<String> result = new HashSet<>();
result.add(Bind.class.getCanonicalName());
return result;
}
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// logic goes here
// as does the actual code generation
//
// we’ll get to this stuff in a little bit
}
}

29. Extending AbstractProcessor
public class AnnotationProcessor extends AbstractProcessor {
private Filer mFiler;
@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init(processingEnv);
mFiler = processingEnv.getFiler();
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public Set<String> getSupportedAnnotationTypes() {
HashSet<String> result = new HashSet<>();
result.add(Bind.class.getCanonicalName());
return result;
}
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// logic goes here
// as does the actual code generation
//
// we’ll get to this stuff in a little bit
}
}

30. Extending AbstractProcessor
public class AnnotationProcessor extends AbstractProcessor {
private Filer mFiler;
@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init(processingEnv);
mFiler = processingEnv.getFiler();
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public Set<String> getSupportedAnnotationTypes() {
HashSet<String> result = new HashSet<>();
result.add(Bind.class.getCanonicalName());
return result;
}
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// logic goes here
// as does the actual code generation
//
// we’ll get to this stuff in a little bit
}
}

31. Extending AbstractProcessor
public class AnnotationProcessor extends AbstractProcessor {
private Filer mFiler;
@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init(processingEnv);
mFiler = processingEnv.getFiler();
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public Set<String> getSupportedAnnotationTypes() {
HashSet<String> result = new HashSet<>();
result.add(Bind.class.getCanonicalName());
return result;
}
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// logic goes here
// as does the actual code generation
//
// we’ll get to this stuff in a little bit
}
}

32. Extending AbstractProcessor
public class AnnotationProcessor extends AbstractProcessor {
private Filer mFiler;
@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init(processingEnv);
mFiler = processingEnv.getFiler();
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public Set<String> getSupportedAnnotationTypes() {
HashSet<String> result = new HashSet<>();
result.add(Bind.class.getCanonicalName());
return result;
}
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// logic goes here
// as does the actual code generation
//
// we’ll get to this stuff in a little bit
}
}

33. Extending AbstractProcessor
public class AnnotationProcessor extends AbstractProcessor {
private Filer mFiler;
@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init(processingEnv);
mFiler = processingEnv.getFiler();
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public Set<String> getSupportedAnnotationTypes() {
HashSet<String> result = new HashSet<>();
result.add(Bind.class.getCanonicalName());
return result;
}
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// logic goes here
// as does the actual code generation
//
// we’ll get to this stuff in a little bit
}
}

34. Extending AbstractProcessor
public class AnnotationProcessor extends AbstractProcessor {
private Filer mFiler;
@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init(processingEnv);
mFiler = processingEnv.getFiler();
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public Set<String> getSupportedAnnotationTypes() {
HashSet<String> result = new HashSet<>();
result.add(Bind.class.getCanonicalName());
return result;
}
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// logic goes here
// as does the actual code generation
//
// we’ll get to this stuff in a little bit
}
}

35. Approach
1. Define the @Bind annotation.
2. Extend AbstractProcessor to create our
annotation processor for @Bind.
3. Within our processor: scan for all fields with
@Bind, keeping track of their parent classes.
4. Generate SoupLadle.java with .bind methods
for each parent class containing bound fields.

36. Processing…
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
if (annotations.isEmpty()) {
return true;
}
Map<TypeElement, List<VariableElement>> bindingClasses = new HashMap<>();
for (Element e : roundEnv.getElementsAnnotatedWith(Bind.class)) {
VariableElement variable = (VariableElement) e;
TypeElement parent = (TypeElement) variable.getEnclosingElement();
List<VariableElement> members;
if (bindingClasses.containsKey(parentClass)) {
members = bindingClasses.get(parentClass);
} else {
members = new ArrayList<>();
bindingClasses.put(parentClass, members);
}
members.add(variable);
}
// .. generate code ..
}

37. Processing…
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
if (annotations.isEmpty()) {
return true;
}
Map<TypeElement, List<VariableElement>> bindingClasses = new HashMap<>();
for (Element e : roundEnv.getElementsAnnotatedWith(Bind.class)) {
VariableElement variable = (VariableElement) e;
TypeElement parent = (TypeElement) variable.getEnclosingElement();
List<VariableElement> members;
if (bindingClasses.containsKey(parentClass)) {
members = bindingClasses.get(parentClass);
} else {
members = new ArrayList<>();
bindingClasses.put(parentClass, members);
}
members.add(variable);
}
// .. generate code ..
}

38. Processing…
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
if (annotations.isEmpty()) {
return true;
}
Map<TypeElement, List<VariableElement>> bindingClasses = new HashMap<>();
for (Element e : roundEnv.getElementsAnnotatedWith(Bind.class)) {
VariableElement variable = (VariableElement) e;
TypeElement parent = (TypeElement) variable.getEnclosingElement();
List<VariableElement> members;
if (bindingClasses.containsKey(parentClass)) {
members = bindingClasses.get(parentClass);
} else {
members = new ArrayList<>();
bindingClasses.put(parentClass, members);
}
members.add(variable);
}
// .. generate code ..
}

39. Processing…
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
if (annotations.isEmpty()) {
return true;
}
Map<TypeElement, List<VariableElement>> bindingClasses = new HashMap<>();
for (Element e : roundEnv.getElementsAnnotatedWith(Bind.class)) {
VariableElement variable = (VariableElement) e;
TypeElement parent = (TypeElement) variable.getEnclosingElement();
List<VariableElement> members;
if (bindingClasses.containsKey(parentClass)) {
members = bindingClasses.get(parentClass);
} else {
members = new ArrayList<>();
bindingClasses.put(parentClass, members);
}
members.add(variable);
}
// .. generate code ..
}

40. Approach
1. Define the @Bind annotation.
2. Extend AbstractProcessor to create our
annotation processor for @Bind.
3. Within our processor: scan for all fields with
@Bind, keeping track of their parent classes.
4. Generate SoupLadle.java with .bind methods
for each parent class containing bound fields.

41. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
} catch (IOException e) {
throw new RuntimeException(e);
}
}

42. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
} catch (IOException e) {
throw new RuntimeException(e);
}
}

43. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
} catch (IOException e) {
throw new RuntimeException(e);
}
}

44. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
} catch (IOException e) {
throw new RuntimeException(e);
}
}
😱

45. There has to be a better way!?

46. There is a better way.

47. Introducing: JavaPoet

48. Introducing: JavaPoet
By Square (Of Course)

49. JavaPoet
• Builder-pattern approach to programmatically
defining a class and its fields/methods.
• Automatically manages the classes needed for
import.
• When you’re ready, it will write clean & readable
Java source to an OutputStream/Writer.

50. JavaPoet - Hello World
TypeSpec.Builder helloWorld = TypeSpec.classBuilder("HelloWorld")
.addModifiers(Modifier.PUBLIC)
.addMethod(MethodSpec.methodBuilder("main")
.addModifiers(Modifier.PUBLIC, Modifier.STATIC)
.returns(void.class)
.addParameter(String[].class, "args")
.addStatement("System.out.println($S + args[0])", "Hello: ")
.build());
JavaFile.builder("jwf.soupladle", helloWorld.build()).build().writeTo(System.out);
package jwf.soupladle;
import java.lang.String;
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello: " + args[0]);
}
}

51. JavaPoet - Hello World
TypeSpec.Builder helloWorld = TypeSpec.classBuilder("HelloWorld")
.addModifiers(Modifier.PUBLIC)
.addMethod(MethodSpec.methodBuilder("main")
.addModifiers(Modifier.PUBLIC, Modifier.STATIC)
.returns(void.class)
.addParameter(String[].class, "args")
.addStatement("System.out.println($S + args[0])", "Hello: ")
.build());
JavaFile.builder("jwf.soupladle", helloWorld.build()).build().writeTo(System.out);
package jwf.soupladle;
import java.lang.String;
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello: " + args[0]);
}
}

52. JavaPoet - Hello World
TypeSpec.Builder helloWorld = TypeSpec.classBuilder("HelloWorld")
.addModifiers(Modifier.PUBLIC)
.addMethod(MethodSpec.methodBuilder("main")
.addModifiers(Modifier.PUBLIC, Modifier.STATIC)
.returns(void.class)
.addParameter(String[].class, "args")
.addStatement("System.out.println($S + args[0])", "Hello: ")
.build());
JavaFile.builder("jwf.soupladle", helloWorld.build()).build().writeTo(System.out);
package jwf.soupladle;
import java.lang.String;
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello: " + args[0]);
}
}

53. JavaPoet - Hello World
TypeSpec.Builder helloWorld = TypeSpec.classBuilder("HelloWorld")
.addModifiers(Modifier.PUBLIC)
.addMethod(MethodSpec.methodBuilder("main")
.addModifiers(Modifier.PUBLIC, Modifier.STATIC)
.returns(void.class)
.addParameter(String[].class, "args")
.addStatement("System.out.println($S + args[0])", "Hello: ")
.build());
JavaFile.builder("jwf.soupladle", helloWorld.build()).build().writeTo(System.out);
package jwf.soupladle;
import java.lang.String;
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello: " + args[0]);
}
}

54. JavaPoet - Hello World
👏
TypeSpec.Builder helloWorld = TypeSpec.classBuilder("HelloWorld")
.addModifiers(Modifier.PUBLIC)
.addMethod(MethodSpec.methodBuilder("main")
.addModifiers(Modifier.PUBLIC, Modifier.STATIC)
.returns(void.class)
.addParameter(String[].class, "args")
.addStatement("System.out.println($S + args[0])", "Hello: ")
.build());
JavaFile.builder("jwf.soupladle", helloWorld.build()).build().writeTo(System.out);
package jwf.soupladle;
import java.lang.String;
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello: " + args[0]);
}
}

55. Approach
1. Define the @Bind annotation.
2. Extend AbstractProcessor to create our
annotation processor for @Bind.
3. Within our processor: scan for all fields with
@Bind, keeping track of their parent classes.
4. Generate SoupLadle.java with .bind methods
for each parent class containing bound fields.

56. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

57. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

58. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

59. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

60. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

61. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

62. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}
"target.$L = ($T) target.findViewById($L)"

63. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}
"target.$L = ($T) target.findViewById($L)"

64. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}
"target.$L = ($T) target.findViewById($L)"

65. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}
"target.$L = ($T) target.findViewById($L)"

66. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

67. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

68. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

69. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}
👀

70. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

71. @Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// .. process annotations ..
try {
JavaFileObject jfo = mFiler.createSourceFile("jwf.soupladle.SoupLadle");
TypeSpec.Builder soupLadleBuilder = TypeSpec.classBuilder("SoupLadle")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
for (Map.Entry<TypeElement, List<VariableElement>> binding : bindingClasses.entrySet()) {
TypeName typeParameter = ClassName.get(binding.getKey());
MethodSpec.Builder bindingBuilder = MethodSpec.methodBuilder("bind")
.addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
.addParameter(typeParameter, "target");
List<VariableElement> members = binding.getValue();
for (VariableElement member : members) {
Bind annotation = member.getAnnotation(Bind.class);
TypeName castClass = ClassName.get(member.asType());
bindingBuilder.addStatement("target.$L = ($T) target.findViewById($L)",
member.getSimpleName().toString(),
castClass,
annotation.value());
}
soupLadleBuilder.addMethod(bindingBuilder.build());
}
AnnotationSpec suppressIdentifierWarningAnnotation = AnnotationSpec.builder(SuppressWarnings.class)
.addMember("value", "$S", "ResourceType").build();
soupLadleBuilder.addAnnotation(suppressIdentifierWarningAnnotation);
JavaFile file = JavaFile.builder("jwf.soupladle", soupLadleBuilder.build()).build();
Writer out = jfo.openWriter();
file.writeTo(out);
out.flush();
out.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return true;
}

72. We’ve got an annotation
processor now!

73. How do we tell the build
process about it?

74. Project/Module Config
• The annotation processor and binding
annotation class need to live in a “regular” java
module.
• Add the android-apt gradle plugin to your root
build.gradle.
• Add dependency records to your app’s
build.gradle.

75. Project/Module Config
• The annotation processor and binding
annotation class need to live in a “regular” java
module.
• Add the android-apt gradle plugin to your root
build.gradle.
• Add dependency records to your app’s
build.gradle.

76. SoupLadle Module

77. SoupLadle Module
apply plugin: 'java'
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.squareup:javapoet:1.7.0'
}

78. SoupLadle Module
jwf.soupladle.AnnotationProcessor

79. SoupLadle Module
include ':app', ':library'

80. Project/Module Config
• The annotation processor and binding
annotation class need to live in a “regular” java
module.
• Add the android-apt gradle plugin to your root
build.gradle.
• Add dependency records to your app’s
build.gradle.

81. Project build.gradle
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.1.3'
classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'
}
}
allprojects {
repositories {
jcenter()
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}

82. Project build.gradle
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.1.3'
classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'
}
}
allprojects {
repositories {
jcenter()
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}

83. Project/Module Config
• The annotation processor and binding
annotation class need to live in a “regular” java
module.
• Add the android-apt gradle plugin to your root
build.gradle.
• Add dependency records to your app’s
build.gradle.

84. App build.gradle
apply plugin: 'com.android.application'
apply plugin: 'com.neenbedankt.android-apt'
android {
compileSdkVersion 24
buildToolsVersion "24.0.2"
defaultConfig {
applicationId "jwf.soupladle.example"
minSdkVersion 16
targetSdkVersion 24
versionCode 1
versionName "1.0"
}
buildTypes {
// .. your build types ..
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:24.1.1'
apt project(':library')
provided project(':library')
}

85. App build.gradle
apply plugin: 'com.android.application'
apply plugin: 'com.neenbedankt.android-apt'
android {
compileSdkVersion 24
buildToolsVersion "24.0.2"
defaultConfig {
applicationId "jwf.soupladle.example"
minSdkVersion 16
targetSdkVersion 24
versionCode 1
versionName "1.0"
}
buildTypes {
// .. your build types ..
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:24.1.1'
apt project(':library')
provided project(':library')
}

86. App build.gradle
apply plugin: 'com.android.application'
apply plugin: 'com.neenbedankt.android-apt'
android {
compileSdkVersion 24
buildToolsVersion "24.0.2"
defaultConfig {
applicationId "jwf.soupladle.example"
minSdkVersion 16
targetSdkVersion 24
versionCode 1
versionName "1.0"
}
buildTypes {
// .. your build types ..
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:24.1.1'
apt project(':library')
provided project(':library')
}

87. Let’s try using it!

88. activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="jwf.soupladle.example.MainActivity">
<TextView
android:id="@+id/hello_world"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"/>
</RelativeLayout>

89. MainActivity.java
package jwf.soupladle.example;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import jwf.soupladle.Bind;
public class MainActivity extends AppCompatActivity {
@Bind(R.id.hello_world)
public TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}

90. MainActivity.java
package jwf.soupladle.example;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import jwf.soupladle.Bind;
public class MainActivity extends AppCompatActivity {
@Bind(R.id.hello_world)
public TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}

91. rebuild project…

92. A wild SoupLadle.java Appears!
package jwf.soupladle;
import android.widget.TextView;
import java.lang.SuppressWarnings;
import jwf.soupladle.example.MainActivity;
@SuppressWarnings("ResourceType")
public final class SoupLadle {
public static final void bind(MainActivity target) {
target.textView = (TextView) target.findViewById(2131427412);
}
}

93. MainActivity.java
package jwf.soupladle.example;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import jwf.soupladle.Bind;
import jwf.soupladle.SoupLadle;
public class MainActivity extends AppCompatActivity {
@Bind(R.id.hello_world)
public TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SoupLadle.bind(this);
textView.setText("The binding worked!");
}
}

96. Thank you! Questions?
Twitter: @jasonwyatt
github.com/jasonwyatt
bandcamp.com/jasonwyatt
Source Code available at:
github.com/jasonwyatt/Soup-Ladle