Invoking annotated methods without creating instances for all the annotated methods

Question

I have two annotations in a class say @annotation_1 and @annotation_2 which means that I have created two instances. ---Please correct this statement if there is any error!

Now, I find all the methods that are annotated with @annotation_1 or @annotation_2, now I need to measure time taken by each annotated method.

e.g.,

      @annotation_1
      Method1
      {
       ...
      }

      @annotation_2
      Method2
      {
       ...
      }

      @annotation_1
      Method3
      {
       ...
      }

      Method4
      {
       ...
      }

Now consider I need to measure nanoTime() for each and every method annotated only with @annotation_1. So I use system.nanotime() to measure the time taken the method before invoking by

startTime = System.nanoTime();

Then I invoke the annotated method using

 Object obj = null;
 try {
                    startTime = System.nanoTime();
                    m.invoke(obj);
                }finally{
                    stopTime = System.nanoTime();
                    runTime = BigDecimal.valueOf(stopTime - startTime);
                }

and then invoking using "m.invoke(obj)", I need to do this because I may be accessing even non-static methods which are annotated with @annotation_1. i.e., I need to invoke Method1 and then find runTime for it, then invoke Method3 and then find runTime for them seperately one after another.

But you could see this invocation creates two instances i.e., for @annotation_1 and @annotation_2, although I consider only "annotation_1" annotated methods.

How do I get rid of this invocation. Is there an alternate method to invoke the methods that are annotated with a specific annotation??

Thanks in advance....:)

Edit : 1

To retrieve the methods:

for(Class<?> currentClass: args){
            List < Method > methods = Arrays.asList(currentClass.getDeclaredMethods());
            for (Method m: methods) {

                Annotation[] annotations = m.getDeclaredAnnotations();

                for (Annotation annotation: annotations) {

                    if ((annotation instanceof annotation_1)) {
                   ... //code to find time by invoking method as given above
                    } else if ((annotation instanceof annotation_2)) {
                       ...//code to find time by invoking method as given above
                    } else
                    {
                        System.err.println("No. definition for annotation :  @"+annotation);
                    }

                }
            }
        }

Args take all the class names in run time.

@YazanJaber I've edited the question... Please take a look... — nt fury, Jul 20 '17 at 10:58
if you don't wish to create multiple instance of the target class, you can cache one instance of the object and use it for all later invocations? — Yazan Jaber, Jul 20 '17 at 11:19

Yazan Jaber · Answer 1 · 2017-07-20T11:27:17.133

0

You only need one instance of the Class that has those methods, after that you can use that object to invoke any of those methods.

edited Jul 20 '17 at 11:27

answered Jul 20 '17 at 10:59

Yazan Jaber

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actually the problem is when I need to call non-static methods I need to create an Instance.... which creates two instances i.e., for annotation_1 and annotation_2. So when I use m.invoke(obj) it invokes both the instances which I don't need because only the instance of the annotated annotation must be created and not both. – nt fury Jul 20 '17 at 11:04
actually grouping the method is not an issue for me. I need to invoke only the instance of the class of that particular annotated method and not all annotations. – nt fury Jul 20 '17 at 11:10
@manoj, when you annotate a method with different annotations, you are not creating any instances. When you use the new keyword or when you use Class.newInstance() method that is when you create an instance. It doesn't matter how many methods are annotated when you create an instance you are creating exactly one instance. – Yazan Jaber Jul 20 '17 at 11:15
if that class has two annotations and when I use Class.newInstance() method it creates an instance of both the annotations right? If this is the case then invoke(obj) with invoke both the instances right? Also I need to use Class.newInstance() because some classes are non-static.... Can you please help me on this? – nt fury Jul 20 '17 at 11:22
It creates a new instance of the target class, and you can use that instance to invoke any method in that class regardless what is it annotated with. – Yazan Jaber Jul 20 '17 at 11:24

Invoking annotated methods without creating instances for all the annotated methods

1 Answers1