Non-Standard Options of the Classic VM
The Java 2 Classic VM is included only in the Java 2 SDK. It is
not included in the Java 2 Runtime Environment.
- -Xbootclasspath:bootclasspath
- Specify a semicolon-separated list of directories, JAR
archives, and ZIP archives to search for boot class files.
These are used in place of the boot class files included in the
Java 2 SDK. Note: Applications that use this option for the
purpose of overriding a class in rt.jar should not be deployed
as doing so would contravene the Java 2 Runtime Environment
binary code license.
- -Xbootclasspath/a:path
- Specify a semicolon-separated path of directires, JAR
archives, and ZIP archives to append to the default bootstrap
class path.
- -Xbootclasspath/p:path
- Specify a semicolon-separated path of directires, JAR
archives, and ZIP archives to prepend in front of the default
bootstrap class path. Note: Applications that use this option
for the purpose of overriding a class in rt.jar should not be
deployed as doing so would contravene the Java 2 Runtime Environment
binary code license.
- -Xdebug
- Start with the debugger enabled. The Java interpereter
prints out a password for jdb's use. Refer to
jdb description for more
details and an example.
- -Xnoclassgc
- Disable class garbage collection
- -Xmsn
- Specify the initial size of the memory allocation pool.
This value must greather than 1000. To multiply the value by
1000, append the letter k. To multiply the value by 1
million, append the letter m. The default value is
1m
- -Xmxn
- Specify the maximum size of the memory allocation pool.
This value must greather than 1000. To multiply the value by
1000, append the letter k. To multiply the value by 1
million, append the letter m. The default value is
64m.
- -Xrunhprof[:help][:<suboption>=<value>,...]
- Enables cpu, heap, or monitor profiling. This option is typically
followed by a list of comma-separated "<suboption>=<value>" pairs.
Run the command java -Xrunhprof:help to obtain a
list of suboptions and their default values.
- -Xrs
- Reduce the use of operating system signals.
- -Xcheck:jni
- Perform additional checks for Java Native Interface
functions.
- -Xcheck:nabounds
- Perform additional checks for Java Native Interface array bounds.
- -Xfuture
- Perform strict class-file format checks. For purposes of backwards
compatibility, the default format checks performed by the
Java 2 SDK's virtual machine are no stricter than
the checks performed by 1.1.x versions of the JDK software. The
-Xfuture flag turns on stricter class-file format checks
that enforce closer conformance to the class-file format
specification. Developers are encouraged to use this flag
when developing new code because the stricter checks will
become the default in future releases of the Java application
launcher.