Java Reference
In-Depth Information
Table 9-3 ( continued )
Option
Description
-M
Do not create a manifest file.
-i
Generate index information for the specified JAR file. It creates an INDEX.LIST file in JAR file under the
META-INF directory.
-0
Do not compress the entries in the JAR file. Only store them. The option value is zero, which means
zero compression.
-e
Add the specified class name as the value for the Main-Class entry in the main section of the
manifest file.
-v
Generate verbose output on the standard output
-C
Change to the specified directory and include the following files in a JAR file. Note that the option is in
uppercase (C). The lowercase (c) is used to indicate the create JAR file option.
Creating a JAR File
Use the following command to create a test.jar JAR file with two class files called A.class and B.class :
jar cf test.jar A.class B.class
If you get an error such as “jar is not recognized as a command” when you run this command, you need to use
the full path of the jar command or add the directory containing the jar command in the PATH environment variable
on your machine. On Windows, if you install the JDK in the C:\java8 directory, the jar command is stored in the
C:\java8\bin directory.
In the above command, the option c indicates that you are creating a new JAR file and the option f indicates that
you are specifying a JAR file name, which is test.jar . At the end of the command, you can specify one or more file
names or directory names to include in the JAR file.
To view the contents of the test.jar file, you can execute the following command:
jar tf test.jar
The option t in this command indicates that you are interested in the table of contents of a JAR file. The option
f indicates that you are specifying the JAR file name, which is test.jar in this case. The above command will
generate the following output:
META-INF/
META-INF/MANIFEST.MF
A.class
B.class
Note that the jar command had automatically created two extra things for you: one directory called META-INF
and a file named MANIFEST.MF in the META-INF directory.
The following command will create a test.jar file by including everything in the current working directory. Note
the use of an asterisk as the wild-card character to denote everything in the current working directory.
jar cf test.jar *
 
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