javah(1)                   OpenBSD Reference Manual                   javah(1)



NAME
       javah - C Header and Stub File Generator

       javah produces C header files and C source files from a Java class.
       These files provide the connective glue that allow your Java and C code
       to interact.

SYNOPSIS
       javah [ options ] fully-qualified-classname. . .
       javah_g [ options ] fully-qualified-classname. . .


DESCRIPTION
       javah 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 an object's instance variables from native source
       code. The .h file contains a struct definition whose layout parallels
       the layout of the corresponding class. The fields in the struct
       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 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. javah can still be used to
       generate native method function proptotypes needed for JNI-style native
       methods. javah produces JNI-style output by default, and places the
       result in the .h file.

       javah_g is a non-optimized version of javah suitable for use with
       debuggers like jdb.

OPTIONS
       -o outputfile
          Concatenates the resulting header or source files for all the
          classes listed on the command line into outputfile. Only one of -o
          or -d may be used.

       -d directory
          Sets the directory where javah saves the header files or the stub
          files. Only one of -d or -o may be used.

       -stubs
          Causes javah to generate C declarations from the Java object file.

       -verbose
          Indicates verbose output and causes javah to print a message to
          stdout concerning the status of the generated files.

       -help
          Print help message for javah usage.

       -version
          Print out javah version information.

       -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.

       -classpath path
          Specifies the path javah uses to look up classes. Overrides the
          default or 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

       As a special convenience, a class path element containing a basename of
       * is considered equivalent to specifying a list of all the files in the
       directory with the extension .jar or .JAR (a java program cannot tell
       the difference between the two invocations).
       For example, if directory foo contains a.jar and b.JAR, then the class
       path element foo/* is expanded to a A.jar:b.JAR, except that the order
       of jar files is unspecified. All jar files in the specified directory,
       even hidden ones, are included in the list. A classpath entry
       consisting simply of * expands to a list of all the jar files in the
       current directory. The CLASSPATH environment variable, where defined,
       will be similarly expanded. Any classpath wildcard expansion occurs
       before the Java virtual machine is started -- no Java program will ever
       see unexpanded wildcards except by querying the environment. For
       example; by invoking System.getenv("CLASSPATH").

       -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.

       -old
          Specifies that old JDK1.0-style header files should be generated.

       -force
          Specifies that output files should always be written.

       -Joption
          Pass option to the Java virtual machine, where option is one of the
          options described on the reference page for the java application
          launcher. For example, -J-Xms48m sets the startup memory to 48
          megabytes.

ENVIRONMENT VARIABLES
       CLASSPATH
          Used to provide the system a path to user-defined classes.
          Directories are separated by colons, for example,


SEE ALSO
       javac, java, jdb, javap, javadoc

                                  05 Aug 2006                         javah(1)
