Is there any way to launch an “empty” JVM instance without giving it a Main class to run?

Question

For example, just to test that a given set of VM parameters "work" and are valid.

I could always make a class with an empty main method or something, but then I have to worry about the classpath and all that jazz, which it'd be nice to avoid.

Answer 1

If you don't want to specify a long classpath, just make an empty java program in whatever directory you're starting the VM from in terminal. You can do that from within the terminal with vi.

Answer 2

You can just execute java -version and add any set of VM parameters that you like. This will parse the parameters and instantiate a VM instance.

For example: java -version -Xmn64m .

You can also do java -Xmn64m abc where abc is a random string. This will report that it could not find the main class "abc" but it will still first parse the Java parameters and instantiate a VM instance. It actually is supposed to execute slightly more initialization tasks than the java -version does so it is good for testing.