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Standard command-line options

The OpenJ9 virtual machine supports the standard Java™ options that are common to all Java virtual machine implementations, including Oracle's HotSpot VM. Some of the common options supported are summarised in the following table:

Standard option name Purpose
-classpath:<resource_name>[:<resource_name>] Sets the search path for application classes and resources (directories and compressed or .jar files). cp can be used instead of classpath.
-help, -? Prints a usage message.
-fullversion Prints the build and version information for a VM
-showversion Prints product version and continues.
-verbose:<option>[,<option>] Enables verbose output. Options include class, dynload, gc, init, jni, sizes and stack. (See Notes)
-version Prints the full build and version information a VM


  • -verbose:class: Writes an entry to stderr for each class that is loaded.
  • -verbose:dynload: Writes detailed class information to stderr as each bootstrap class is loaded by the VM:
  • -verbose:gc: Provides verbose garbage collection information.
  • -verbose:init: Writes information to stderr describing VM initialization and termination.
  • -verbose:jni: Writes information to stderr describing the JNI services called by the application and VM.
  • -verbose:sizes: Writes information to stderr describing the active memory usage settings.
  • -verbose:stack: Writes information to stderr describing the Java and C stack usage for each thread.

For more information about standard options, see Oracle Java SE Standard Options