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javah - Unix, Linux Command
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
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. OPTIONS
The following options are supported:
Tag | Description |
-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.
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-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.
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-classpath path |
Specifies the path
javah uses to look up classes. Overrides
the default of the
CLASSPATH environment variable if it is
set. Directories are separated by colons. Thus the general
format for path is:
Tag | Description |
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.:<your_path>
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For example:
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Tag | Description |
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.:/home/avh/classes:/usr/local/java/classes
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Tag | Description |
-d directory |
Sets the directory where
javah saves the header files or the
stub files.
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-force |
Specifies that output files should always be written.
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-help |
Prints help message for
javah usage.
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-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.
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-old |
Specifies the old JDK1.0-style header files should be
generated.
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-stubs |
Causes
javah to generate C declarations from the Java object
file.
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-trace |
Tracing is no longer supported.
Instead, use the
-verbose:jni option of the virtual machine.
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-verbose |
Indicates verbose output and causes
javah to print a message
to
stdout concerning the status of the generated files.
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-version |
Print out javah version information.
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-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 underlying virtual machine.
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ENVIRONMENT VARIABLES
Tag | Description |
CLASSPATH |
Used to provide the system with a path to user-defined classes.
Directories are separated by colons, for example,
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Tag | Description |
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.:/home/avh/classes:/usr/local/java/classes |
SEE ALSO
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