java – 为什么getAnnotation不接受Class <?扩展Annotation>

为什么后续行在Java中产生编译错误?或者我如何编写正确的泛型语法?

Class<? extends Annotation> annotation = annotations[i];
Class<? extends Annotation> anno = javaClass.getAnnotation(annotation);

该方法的签名是:

public <A extends Annotation> A getAnnotation(Class<A> annotationClass)

从Eclipse编译错误:

Type mismatch: cannot convert from capture#5-of ? extends Annotation to Class<? extends Annotation>

从javac编译错误:

incompatible types
    Class<? extends Annotation> anno = javaClass.getAnnotation(annotation);
                                                              ^
 required: Class<? extends Annotation>
 found:    CAP#1
 where CAP#1 is a fresh type-variable:
   CAP#1 extends Annotation from capture of ? extends Annotation

解决方法:

getAnnotation返回注释本身 – 而不是注释的类.我怀疑你可以使用:

Class<? extends Annotation> annotationClass = annotations[i];
Annotation annotation = javaClass.getAnnotation(annotationClass);
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