Is there any way to judge whether a class has been loaded into jvm?

Question

Is there any way to judge whether a class has been loaded into jvm? In my opinion,I think the way is findClass ,is that right?

This depends on what you requirements are. Is it when the class is searched for, loaded via byte code and thus has a `.class` object, or when it's initialised? — Peter Lawrey, Apr 10 '17 at 06:51
May be it is loaded,and then is deleted .So I think I can not judge from the object class,such as aop mechanism. — flower, Apr 10 '17 at 06:58
The real question is probably: why do you think that matters? In other words: what is the problem you intend to solve by doing such a judgement? — GhostCat, Apr 10 '17 at 07:01

score 1 · Accepted Answer · answered Apr 10 '17 at 08:19

1

OK, so I have not done this. But it seems that it would be possible via getAllLoadedClasses() in the Instrumentation API.

But then you would still need to start the JVM with your agent.

answered Apr 10 '17 at 08:19

Eugene

Depending on the JVM, you may load agents after the start dynamically, e.g. via the Attach API. At the end of [this answer](http://stackoverflow.com/a/19912148/2711488) is an example program that attaches to its own JVM to load itself as agent to finally get hands on the `Instrumentation` API. – Holger Apr 24 '17 at 23:25

score 0 · Answer 2 · answered Apr 10 '17 at 08:14

0

Turn on class loader logging with -verbose:class and read the log.

answered Apr 10 '17 at 08:14

Joni

1

what if you have already started the JVM and it is running at the moment? – Eugene Apr 10 '17 at 08:14

score 0 · Answer 3 · answered Apr 10 '17 at 08:57

0

You can use jdk tool,such as JConsole.

answered Apr 10 '17 at 08:57

flower

3 Answers3