How to check if a parameter of the current method has an annotation and retrieve that parameter value in Java?

Question

Consider this code:

public example(String s, int i, @Foo Bar bar) {
  /* ... */
}

I want to check if the method has an annotation @Foo

Answer 1

getParameterAnnotations returns an array with the length equals to the amount of method parameters. Each element in that array contains an array of annotations on that parameter.
So getParameterAnnotations()[2][0] contains the first ([0]) annotation of the third ([2]) parameter.

If you only need to check if at least one parameter contains an annotation of a specific type, the method could look like this:

private boolean isAnyParameterAnnotated(Method method, Class annotationType) {
    final Annotation[][] paramAnnotations = method.getParameterAnnotations();    
    for (Annotation[] annotations : paramAnnotations) {
        for (Annotation an : annotations) {
            if(an.annotationType().equals(annotationType)) {
                return true;
            }
        }
    }
    return false;
}