What is annotation processing in Java?

Question

Class names, 'HelloWorldApp', are only accepted if annotation processing is explicitly requested

What does it mean? And how to apply it?

https://docs.oracle.com/javase/tutorial/getStarted/problems/index.html — ROMANIA_engineer, Jan 08 '16 at 23:55

score 22 · Accepted Answer · edited Jul 02 '22 at 05:02

22

"Annotation Processing" is a hook into the compile process of the java compiler, to analyse the source code for user defined annotations and handle then (by producing compiler errors, compiler warning, emitting source code, byte code ...).

API reference: javax.annotation.processing (Java Platform SE 6).

edited Jul 02 '22 at 05:02

Sergey Vyacheslavovich Brunov

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answered Jan 27 '10 at 10:47

Arne Deutsch

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Paul Wagland · Answer 2 · 2018-11-15T12:44:53.610

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From the very next line of the page that you refer to:

Class names, 'HelloWorldApp', are only accepted if annotation processing is explicitly requested

If you receive this error, you forgot to include the .java suffix when compiling the program. Remember, the command is javac HelloWorldApp.java not javac HelloWorldApp.

That is, the string that you are referring to is a possible error that you might get when trying to compile the examples. The very next line in the document, tells you how to resolve the issue.

If you want to know more about annotations, what they are, and how to use them, then I would suggest to go through the Annotations tutorial.

edited Nov 15 '18 at 12:44

answered Jan 27 '10 at 10:53

Paul Wagland

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Question: "What is annotation processing in Java?" – Daniel Earwicker Jan 27 '10 at 10:55
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@Earwicker: That is the title of the question, now read the text of the question: this page says blah, what does that mean? – Paul Wagland Jan 27 '10 at 10:58
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Yeah, I read it. It doesn't say the OP has hit *any* kind of compile error they can't fix. It says (again) they want to know what annotation processing is. – Daniel Earwicker Jan 27 '10 at 11:02
@Earwicker: I have updated my answer to answer both interpretations of the question. – Paul Wagland Jan 27 '10 at 11:34
Link to 'Annotations tutorial' is not valid – Marek J. Oct 15 '18 at 07:55

score 2 · Answer 3 · answered Aug 04 '12 at 07:47

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This error is due to incorrect use of java compilation command i.e javac with file name w/o java extension (.java)

Use proper compilation command

javac HelloWorldApp.java

Command used foe execution

java HelloWorldApp

answered Aug 04 '12 at 07:47

jaibardhan

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What is annotation processing in Java?

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