javah(1) Basic Tools javah(1)
NAME
javah - Generates C header and source files from a Java class.
SYNOPSIS
javah [ options ] fully-qualified-class-name ...
options
The command-line options. See Options.
fully-qualified-class-name
The fully qualified location of the classes to be converted to C header and source
files.
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 an
object's instance variables from native source code. The .h file contains a struct
definition with a layout that 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. When the class passed to the javah command is inside a package, the package
name is added to the beginning of both the header file name and the structure name.
Underscores (_) are used as name delimiters.
By default the javah command 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 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. The javah command produces JNI-style output by default and
places the result in the .h file.
OPTIONS
-o outputfile
Concatenates the resulting header or source files for all the classes listed on the
command line into an output file. Only one of -o or -d can be used.
-d directory
Sets the directory where the javah command saves the header files or the stub
files. Only one of -d or -o can be used.
-stubs
Causes the javah command to generate C declarations from the Java object file.
-verbose
Indicates verbose output and causes the javah command to print a message to stdout
about the status of the generated files.
-help
Prints a help message for javah usage.
-version
Prints javah command release information.
-jni
Causes the javah command to create an output file containing JNI-style native
method function prototypes. This is the default output; use of -jni is optional.
-classpath path
Specifies the path the javah command uses to look up classes. Overrides the default
or the CLASSPATH environment variable when it is set. Directories are separated by
colons on Oracle Solaris and semicolons on Windows. The general format for path is:
Oracle Solaris:
.:your-path
Example: .:/home/avh/classes:/usr/local/java/classes
Windows:
.;your-path
Example: .;C:\users\dac\classes;C:\tools\java\classes
As a special convenience, a class path element that contains a base name of * is
considered equivalent to specifying a list of all the files in the directory with
the extension .jar or .JAR.
For example, if directory mydir contains a.jar and b.JAR, then the class path
element mydir/* is expanded to a A.jar:b.JAR, except that the order of jar files is
unspecified. All JAR files in the specified directory, including hidden ones, are
included in the list. A class path entry that consists of * expands to a list of
all the JAR files in the current directory. The CLASSPATH environment variable,
where defined, is similarly expanded. Any class path wild card expansion occurs
before the Java Virtual Machine (JVM) is started. A Java program will never see
unexpanded wild cards except by querying the environment. For example, by calling
System.getenv("CLASSPATH").
-bootclasspath path
Specifies the path from which to load bootstrap classes. By default, the bootstrap
classes are the classes that implement the core Java platform located in
jre\lib\rt.jar and several other JAR files.
-old
Specifies that old JDK 1.0-style header files should be generated.
-force
Specifies that output files should always be written.
-Joption
Passes 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 MB. See java(1).
SEE ALSO
o javah(1)
o java(1)
o jdb(1)
o javap(1)
o javadoc(1)
JDK 8 21 November 2013 javah(1)
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