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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-

       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:

       -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.

       -bootclasspath path
                      Specifies path from which to load bootstrap classes.  By
                      default,  the  bootstrap  classes are the classes imple-
                      menting  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. 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:


                      For example:


       -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.

       -old           Specifies  the  old  JDK1.0-style header files should be

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

       -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

       -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 underly-
                      ing virtual machine.


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



       java(1), javac(1), javadoc(1), javap(1), jdb(1)

                                 13 June 2000                         javah(1)

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