Viewing the Contents of a JAR File

jar tf <jar file name>

The t option indicates that you want to view the table of contents of the JAR file.
The f option indicates that the JAR file whose contents are to be viewed is specified on the command line.

You could also use v option, which will give you additional information.

OperationCommand
To create a JAR filejar cf jar-file input-file(s)
To view the contents of a JAR filejar tf jar-file
To extract the contents of a JAR filejar xf jar-file
To extract specific files from a JAR filejar xf jar-file archived-file(s)
To run an application packaged as a JAR file (requires the Main-class manifest header)
java -jar app.jar
To invoke an applet packaged as a JAR file
<applet code=AppletClassName.class
        archive="JarFileName.jar"
        width=width height=height>
</applet>