Created
April 30, 2018 21:09
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public class GenericNestedType { | |
@Retention(RetentionPolicy.RUNTIME) | |
@Target(ElementType.TYPE_USE) | |
@interface SampleTypeAnnotation { } | |
static class GenericNested<T> { | |
class Inner { } | |
} | |
@SampleTypeAnnotation GenericNested<?>. Inner foo; | |
GenericNested<?>.@SampleTypeAnnotation Inner bar; | |
public static void main(String[] args) throws Exception { | |
Field foo = GenericNestedTypeDemo.class.getDeclaredField("foo"); | |
System.out.println(foo.getAnnotatedType().getType().toString()); | |
System.out.println(foo.getAnnotatedType().getAnnotations().length); | |
System.out.println(foo.getAnnotatedType().getAnnotatedOwnerType().getType().toString()); | |
System.out.println(foo.getAnnotatedType().getAnnotatedOwnerType().getAnnotations().length); | |
Field bar = Foo.class.getDeclaredField("bar"); | |
System.out.println(bar.getAnnotatedType().getType().toString()); | |
System.out.println(bar.getAnnotatedType().getAnnotations().length); | |
System.out.println(bar.getAnnotatedType().getAnnotatedOwnerType().getType().toString()); | |
System.out.println(bar.getAnnotatedType().getAnnotatedOwnerType().getAnnotations().length); | |
} | |
} |
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public class GenericReceiverDemo<T> { | |
@Retention(RetentionPolicy.RUNTIME) | |
@Target(ElementType.TYPE_USE) | |
@interface SampleTypeVariable { } | |
void foo(Foo<@SampleTypeVariable T> this) { } | |
public static void main(String[] args) throws Exception { | |
Method foo = GenericReceiverDemo.class.getDeclaredMethod("foo"); | |
AnnotatedType receiverType = foo.getAnnotatedReceiverType(); | |
// No chance to find out that the parameter type T was annotated, despite the annotation being present in the class file. | |
System.out.println(receiverType.getType() instanceof ParameterizedType); | |
} | |
} |
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public class TypeVariableBoundDemo { | |
@Retention(RetentionPolicy.RUNTIME) | |
@Target(ElementType.TYPE_USE) | |
@interface SampleTypeVariable { } | |
<T, S extends @SampleTypeVariable T, U extends @SampleTypeVariable Object> void foo() { } | |
public static void main(String[] args) throws Exception { | |
Method foo = TypeVariableBoundDemo.class.getDeclaredMethod("foo"); | |
TypeVariable<Method>[] typeParameters = foo.getTypeParameters(); | |
TypeVariable<?> s = typeParameters[1]; | |
AnnotatedType[] annotatedBoundsOfS = s.getAnnotatedBounds(); | |
System.out.println(annotatedBoundsOfS[0].getDeclaredAnnotations().length); | |
TypeVariable<?> u = typeParameters[2]; | |
AnnotatedType[] annotatedBoundsOfU = u.getAnnotatedBounds(); | |
System.out.println(annotatedBoundsOfU[0].getDeclaredAnnotations().length); | |
} | |
} |
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public class TypeVariableBoundsDemo<T extends Callable<@Foo.SampleTypeAnnotation ?> & List<@Foo.SampleTypeAnnotation ?>> { | |
@Retention(RetentionPolicy.RUNTIME) | |
@Target(ElementType.TYPE_USE) | |
@interface SampleTypeAnnotation { } | |
public static void main(String[] args) throws Exception { | |
TypeVariable<Class<Foo>>[] variables = TypeVariableBoundsDemo.class.getTypeParameters(); | |
AnnotatedType[] bounds = variables[0].getAnnotatedBounds(); | |
System.out.println(bounds[0] instanceof AnnotatedParameterizedType); | |
AnnotatedParameterizedType callable = (AnnotatedParameterizedType) bounds[0]; | |
callable.getAnnotatedActualTypeArguments(); // throws exception | |
} | |
} |
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