Can a method figure out its own name using reflection in Java

Question

I know that you can use reflection in Java to get the name of class, methods, fields...etc at run time. I was wondering can a method figure out its own name while its inside it's self? Also, I don't want to pass the name of the method as a String parameter either.

For example

public void HelloMyNameIs() {
  String thisMethodNameIS = //Do something, so the variable equals the method name HelloMyNameIs. 
}

If it that is possible, I was thinking it would probably involve using reflection, but maybe it doesn't.

If anybody know, it would be greatly appreciated.

Not with reflection, no, answer here: http://stackoverflow.com/questions/442747/getting-the-name-of-the-current-executing-method-java — Affe, Aug 02 '11 at 23:19

score 9 · Accepted Answer · answered Aug 02 '11 at 23:18

9

Use:

public String getCurrentMethodName()
{
     StackTraceElement stackTraceElements[] = (new Throwable()).getStackTrace();
     return stackTraceElements[1].toString();
}

inside the method you want to get the name of.

public void HelloMyNameIs()
{
    String thisMethodNameIS = getCurrentMethodName();
}

(Not reflection, but I don't think it is possible.)

answered Aug 02 '11 at 23:18

Evan Mulawski

54,662
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3

There are performance implications with this technique, so use with caution. But it's the best solution you're going to get. – Kirk Woll Aug 02 '11 at 23:20
@Kirk Woll: Very true. And because of that, it really shouldn't be used in a release build, only for debugging purposes. – Evan Mulawski Aug 02 '11 at 23:22
Great advice about performance and the ability to find out a method name inside of itself. I guess, I will steer clear of using this technique because it would effect the speed of the build. – grebwerd Aug 02 '11 at 23:25
1

Why not use Thread.currentThread().getStackTrace() instead of new Throwable? – Andrejs Mar 25 '12 at 18:09
@Andrejs: If you read the documentation, both retrieve the stack trace from the current thread. – Evan Mulawski Mar 25 '12 at 18:21
1

But only one of them creates an extra Throwable object – Andrejs Mar 25 '12 at 18:37
1

Its possible to avoid this extra object creation, that's all – Andrejs Mar 25 '12 at 21:05

score 6 · Answer 2 · answered Mar 25 '12 at 18:04

6

This one-liner works using reflection:

public void HelloMyNameIs() {
  String thisMethodNameIS = new Object(){}.getClass().getEnclosingMethod().getName();
}

The downside is that the code can't be moved to a separate method.

answered Mar 25 '12 at 18:04

Andrejs

26,885
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score 3 · Answer 3 · answered Aug 03 '11 at 00:24

Using a Proxy all your methods (that override a method defined in an interface) can know their own names.

import java . lang . reflect . * ;

interface MyInterface
{
      void myfun ( ) ;
}

class MyClass implements MyInterface
{
      public void myfun ( ) { /* implementation */ }
}

class Main
{
      public static void main ( String [ ] args )
      {
            MyInterface m1 = new MyClass ( ) ;
            MyInterface m2 = ( MyInterface ) ( Proxy . newProxyInstance (
                  MyInterface . class() . getClassLoader ( ) ,
                  { MyInterface . class } ,
                  new InvocationHandler ( )
                  {
                        public Object invokeMethod ( Object proxy , Method method , Object [ ] args ) throws Throwable
                        {
                             System . out . println ( "Hello.  I am the method " + method . getName ( ) ) ;
                             method . invoke ( m1 , args ) ;
                        }
                  }
            ) ) ;
            m2 . fun ( ) ;
      }
}

score 0 · Answer 4 · answered Sep 12 '13 at 09:52

0

Stack trace from current thread also:

public void aMethod() {  
    System.out.println(Thread.currentThread().getStackTrace()[0].getMethodName()); 
}

answered Sep 12 '13 at 09:52

Nagaraja G Devadiga

397
2
6

Can a method figure out its own name using reflection in Java

4 Answers4