SUN's Java distribution has an archive tool called jar. The jar tool is a Java application that combines multiple files into a single JAR archive file. The jar tool also compresses files. In addition, it allows individual entries in a file to be signed with a digital signature so that their origin can be authenticated. This is important for authors of Java applets and application which will be sent across a network. See Unix tool jarsigner for signing jar files.
The syntax for the jar tool is almost identical to the syntax for the Unix tar command. See the Unix man page.
% man jar
Here is a simple use of jar to archive all the .java files in a directory.
% jar cvf myJar.jar *.java
added manifest
adding: Bank.java(in = 1124) (out= 938)(deflated 16%)
adding: Customer.java(in = 2235) (out= 661)(deflated 70%)
%
To retrieve the files from a JAR archive, type the following:
% jar xvf myJar.jar
created: META-INF/
extracted: META-INF/MANIFEST.MF
extracted: Bank.java
extracted: Customer.java
Any file can be in a JAR archive such as images and a ReadMe file.
To create a .jar file which you can run, you need to create a manifest file (MyManifest) which has in it the line
Main-Class: classname
where "classname" is the name of your class with the "main" method.
Make sure a "Return" is entered after the line.
Then create the .jar file as
% jar cmf MyManifest myJar.jar *.class
where myJar.jar is name of the new .jar file and *.class is all the class
files in the current directory.
To run, type the following:
% java -jar myJar.jar
You may include images such as gifs and jpegs in the runnable file as
well. In that case, place all the gif, jpeg, and .class files in one
directory and jar that.