You can use the -XshowSettings flag in the Hotspot JVM version 1.7 and up (not supported in 1.6):

OpenJDK has had support for this flag since late 2010.

Seen in http://marxsoftware.blogspot.de/2016/02/hotspot-jvm-XshowSettings.html

The Oracle JVM ships with the tool jcmd which allows you to see the flags present in a running JVM. See:

https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr006.html

For this use case, you could use:

参考文献

Reading Java system properties from command line