which objects use heap space?

[Thomas Schatzl]

Hi Li,

On Mon, 2014-07-07 at 11:33 +0800, Li Li wrote:
> I have a class without any space allocation, but by using jmap -heap,
> I found about 400K space is used. is it allocated by jvm?
> 
> public class TestGc2 {
> public static void main(String[] args) throws Exception {
> waitEnter("waiting gc...");
> waitEnter("before exit");
> }
> public static void test() throws Exception{
> 
> }
> private static void waitEnter(String s) throws IOException{
> System.out.println(s);
> System.in.read();
> System.gc();
> }
> }

  as you thought, VM initialization creates a few objects for various
purposes. These includes instances of some system objects that always
need to be available, some metadata, or objects referenced by static
fields. Also the instance of your application class needs to be
allocated.

I cannot say whether 400k is about what you can expect.

Thomas