Question

Let’s say I have a situation like this:

public String method(String s) {
    return stringForThisVisibility(s, EnumVisibility.PUBLIC);
}

and I want to replace it with an annotation like this:

@VisibilityLevel(value = EnumVisibility.PUBLIC)
public String method(String s) {
    return stringForThisVisibility(s);
}

This seems to be a better and more clear solution, but i need for stringForThisVisibility method to know value of @VisibilityLevel with some kind of reflection. Is that possible? Can I see the annotations on the method calling stringForThisVisibility?

Answer 1

You need to obtain the Method object that represents the method that called stringForThisVisibility. Unfortunately, Java doesn’t offer this functionality out of the box.

However, we can still obtain the Method via the information returned by Thread.currentThread().getStackTrace(). That method returns an array of StackTraceElement objects. Each StackTraceElement object tells us three things:

• The name of the class (getClassName())
• The name of the method (getMethodName())
• The line number (getLineNumber())

It may take some experimentation, but you should find which index in that array represents the method you’re interested in (it will probably be the first, second or third StackTraceElement in the array).

Once you have the desired StackTraceElement, you can obtain its corresponding Method object using the technique in my answer to the question entitled “Get caller’s method (java.lang.reflect.Method)”. That technique will still word, even if the class has more than one method with that method name. There are simpler techniques if you’re not worried about that scenario.

Once you have the Method object, it’s just a matter of calling method.getAnnotation(VisibilityLevel.class).