Java Reference
In-Depth Information
Notes
The syntax of the
jar
command is intentionally very similar to that of the Unix
tar
command. This similarity is the reason why
jar
uses command options, rather than
switches (as the other Java platform commands do).
When creating a
.jar
file, the
jar
tool will automatically add a directory called
META-INF
that contains a file called
MANIFEST.MF
—this is metadata in the form
of headers paired with values. By default,
MANIFEST.MF
contains just two headers:
Manifest-Version: 1.0
Created-By: 1.8.0 (Oracle Corporation)
By using the
m
option, additional metadata can be added into
MANIFEST.MF
at JAR
creation time. One frequently added piece is the
Main-Class:
attribute, which indi‐
cates the entry point into the application contained in the JAR. A JAR with a speci‐
fied
Main-Class:
can be directly executed by the JVM, via
java -jar
.
The addition of the
Main-Class:
attribute is so common that
jar
has the
e
option
to create it directly in
MANIFEST.MF
, rather than having to create a separate text
file for this purpose.
s
d
m
P
r
o
i
l
e
s
javadoc
Basic usage
javadoc some.package
Description
javadoc
produces documentation from Java source files. It does so by reading a spe‐
cial comment format (known as Javadoc comments) and parsing it into a standard
documentation format, which can then be output into a variety of document for‐
mats (although HTML is by far the most common).
For a full description of Javadoc syntax, refer to
Chapter 7
.
Common switches
-cp <classpath>
Define the classpath to use
-D <directory>
Tell
javadoc
where to output the generated docs
-quiet
Suppress output except for errors and warnings
Notes
The platform API docs are all written in Javadoc.
