JVM选项中XX的全名是什么？

Question

While reading the documentation of JDK1.8 , I'm very curious about the abbreviation XX.

Take -XX:ErrorFile=filename for example, no question about the usage, can any one tell me the full name of the abbreviation XX ?

Thanks

Answer 1

The best answer I could find is at http://www.ibm.com/support/knowledgecenter/SSYKE2_7.0.0/com.ibm.java.lnx.70.doc/diag/appendixes/cmdline/commands_jvm_xx.html . Quoting from the link :

Java VM command-line options that are specified with -XX: are not checked for validity. If the VM does not recognize the option, the option is ignored. These options can therefore be used across different VM versions without ensuring a particular level of the VM.

Answer 2

It's a long programming tradition to use "dash" or "double-dash" command-line parameters. Likewise, using the same letter twice means "even more so". So "-v" for verbose, "-vv" for even more verbose. "X" means "unknown" or "hidden" or even "dangerous".