java 注释匿名内部类
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Annotate anonymous inner class
提问by Mark Pope
Is there a way to annotate an anonymous inner class in Java?
有没有办法在 Java 中注释匿名内部类？
In this example could you add a class level annotation to Class2?
在这个例子中，你可以给 Class2 添加一个类级别的注释吗？
public void method1() {
add(new Class2() {
public void method3() {}
});
}
采纳答案by dty
No. You'd need to promote it to a "proper" class. It can still be scoped within the outer class if necessary, so it doesn't need to be a top-level class, or public, or whatever. But it does need a proper class definition to attach the annotation to.
不，您需要将其提升为“适当”的课程。如有必要，它仍然可以在外部类内进行作用域，因此它不需要是顶级类、公共类或其他类。但它确实需要一个适当的类定义来附加注释。
回答by yegor256
回答by jan.supol
Yes, as mentioned by yegor256, it is possible, since JDK 8 adopted JSR 308 (type annotations).
是的，正如 yegor256 所提到的，这是可能的，因为JDK 8 采用了 JSR 308 (type annotations)。
So now whenever an annotation is decorated by @Target({ElementType.TYPE_USE}), it can be used for annotating an anonymous class at runtime. For instance:
所以现在每当一个注解被 修饰时@Target({ElementType.TYPE_USE})，它就可以用于在运行时注解匿名类。例如：
@Target({ ElementType.TYPE_USE })
@Retention(RetentionPolicy.RUNTIME)
@interface MyAnnotation {
String value();
}
Object o = new @MyAnnotation("Hello") Object() {};
The tricky part is how to access the annotation:
棘手的部分是如何访问注释：
Class<?> c = o.getClass();
AnnotatedType type = c.getAnnotatedSuperclass();
System.out.println(Arrays.toString(type.getAnnotations()));
