[英]Why does the List<? extends Foo> not accept an object of the Foo class?
[英]Why getAnnotation does not accept Class<? extends 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
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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