java8-tutorial/src/com/winterbe/java8/Annotations1.java at master · ericwang1984/java8-tutorial

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package com.winterbe.java8;

import java.lang.annotation.ElementType;

import java.lang.annotation.Repeatable;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

/**

* @author Benjamin Winterberg

public class Annotations1 {

@Target({ElementType.TYPE_PARAMETER, ElementType.TYPE_USE})

@interface MyAnnotation {

}

@Retention(RetentionPolicy.RUNTIME)

@interface Hints {

Hint[] value();

}

@Repeatable(Hints.class)

@Retention(RetentionPolicy.RUNTIME)

@interface Hint {

String value();

}

@Hint("hint1")

@Hint("hint2")

class Person {

}

public static void main(String[] args) {

Hint hint = Person.class.getAnnotation(Hint.class);

System.out.println(hint); // null

Hints hints1 = Person.class.getAnnotation(Hints.class);

System.out.println(hints1.value().length); // 2

Hint[] hints2 = Person.class.getAnnotationsByType(Hint.class);

System.out.println(hints2.length); // 2

}