javah(1) javah(1)
NAME
javah - C header and stub file generator
SYNOPSIS
javah [ options ] fully-qualified-classname ...
javah_g [ options ] fully-qualified-classname ...
DESCRIPTION
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 delimiters.
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 concate-nate concatenate
nate 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.
OPTIONS
The following options are supported:
-o outputfile Concatenates the resulting header or source files for all the classes listed on the
command line into outputfile. Only the -o or -d option may be used.
-bootclasspath path
Specifies path from which to load bootstrap classes. By default, the bootstrap
classes are the classes implementing the core Java 2 platform located in
jre/lib/rt.jar and several other jar files.
-classpath path
Specifies the path javah uses to look up classes. Overrides the default of the CLASS-PATH CLASSPATH
PATH 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 pro-totypes. prototypes.
totypes. This is the default output, so use of -jni is optional.
-old Specifies the old JDK1.0-style header files should be generated.
-stubs Causes javah to generate C declarations from the Java object file.
-trace Tracing is no longer supported. Instead, use the -verbose: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 Print out javah version information.
-Joption 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 underlying virtual machine.
ENVIRONMENT VARIABLES
CLASSPATH Used to provide the system with a path to user-defined classes. Directories are sepa-rated separated
rated by colons, for example,
.:/home/avh/classes:/usr/local/java/classes
SEE ALSO
java(1), javac(1), javadoc(1), javap(1), jdb(1)
13 June 2000 javah(1)
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