Summary

java command's -Xdebug and -debug options will be deprecated for removal.

Problem

java command allows the -Xdebug and -debug options to be used during launch. The -debug option has been an alias for the -Xdebug option. -debug isn't documented but the -Xdebug is and as noted in the documentation (dating as far back as Java 8), this option is only there for backward compatibility and currently does nothing https://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html#BGBCIEFC

-Xdebug

Does nothing. Provided for backward compatibility.

There are applications which currently pass this option when launching java. Most of these usages are of the form:

-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=5005

These usages appear to be copy/pasted and are being used when launching java with debugging enabled. The use of -Xdebug and -debug plays no role in launching java in debug mode or any other functionality provided by java.

Solution

java launcher will start printing a warning message if -debug or -Xdebug is passed. The warning message will state that the option is deprecated and will be removed in a future release:

java -debug -version                                     
Warning: -debug option is deprecated and may be removed in a future release.
...

similarly:

java -Xdebug -version
OpenJDK 64-Bit Server VM warning: Option -Xdebug was deprecated in JDK 22 and will likely be removed in a future release.
...

Specification

There are no specification changes.