javah(1) javah(1)
javah - C header and stub file generator
javah [ options ] fully-qualified-classname ...
javah_g [ options ] fully-qualified-classname ...
The javah command generates C header and source files that are needed
to implement native methods. The generated header and source files are
used by C programs to reference instance variables of an object from
native source code. The .h file contains a structure definition whose
layout parallels that of the corresponding class. The fields in the
structure correspond to instance variables in the class.
The name of the header file and the structure declared within it are
derived from the name of the class. If the class passed to javah is
inside a package, the package name is prepended to both the header file
name and the structure name. Underscores ( _ ) are used as name delim-
iters.
By default, javah creates a header file for each class listed on the
command line and puts the files in the current directory. Use the
-stubs option to create source files. Use the -o option to concatenate
the results for all listed classes into a single file.
The new native method interface, Java Native Interface (JNI), does not
require header information or stub files. The javah command can still
be used to generate native method function prototypes needed for JNI-
style native methods. javah produces JNI-style output by default, and
places the result in the .h file.
The javah_g version is a non-optimized version of javah suitable for
use with debuggers like jdb.
The following options are supported:
-bootclasspath path
Specifies path from which to load bootstrap classes. By
default, the bootstrap classes are the classes imple-
menting the core Java platform located in jre/lib/rt.jar
and jre/lib/charsets.jar.
-classpath path
Specifies the path javah uses to look up classes. Over-
rides the default of the CLASSPATH environment variable
if it is set. Directories are separated by colons. Thus
the general format for path is:
.:<your_path>
For example:
.:/home/avh/classes:/usr/local/java/classes
-d directory Sets the directory where javah saves the header files or
the stub files.
-force Specifies that output files should always be written.
-help Prints help message for javah usage.
-jni Causes javah to create an output file containing JNI-
style native method function prototypes. This is the
default output, so use of -jni is optional.
-o outputfile Concatenates the resulting header or source files for
all the classes listed on the command line into output-
file. Only the -o or -d option may be used.
-old Specifies the old JDK1.0-style header files should be
generated.
-stubs Causes javah to generate C declarations from the Java
object file. Only the -o or -d option may be used.
-trace Tracing is no longer supported. Instead, use the -ver-
bose:jni option of the virtual machine.
-verbose Indicates verbose output and causes javah to print a
message to stdout concerning the status of the generated
files.
-version Prints build version.
J option Pass option to the Java virtual machine, where option is
one of the options described on the man page for the
java application launcher, java(1). For example, -J-
Xms48m sets the startup memory to 48 megabytes. It is a
common convention for -J to pass options to the underly-
ing virtual machine.
CLASSPATH Used to provide the system with a path to user-defined
classes. Directories are separated by colons, for exam-
ple,
.:/home/avh/classes:/usr/local/java/classes
java(1), javac(1), javadoc(1), javap(1), jdb(1)
13 June 2000 javah(1)