jar.exe : Java Glossary

Usage:

jar {ctxu}[vfm0M] [jar-file] [manifest-file] [-C dir] files ...

REM Examine the contents of a jar, and test integrity
jar.exe -tf myjar.jar

REM For a sorted list, use my JarLook utility
REM available from http://mindprod.com/products1.html#JARLOOK
java.exe -jar jarlook.jar myjar.jar

REM With separate flags, jar.exe will NOT work.
jar.exe -t -f myjar.jar

Prepare a skeleton manifest main.mft file to define your main class that looks like this:

Main-Class com.mindprod.Bulk

Note that the following technique will not work. You will get NoClassDefFoundErrors.

Jar.exe has no intelligence or common sense. It will mindlessly create jars that have packages and member names out of sync that have no chance of working without even a warning message.

Avoid C:\ on the class files to be included, or the C:\ may be improperly included as part of the package name. WinZip will disguise the damage, but JarLook will show it to you.

The jar.exe file itself lives in 

forjar.list

You will waste hundreds of hours maintaining lists of files that need to go in each jar. If you do this manually, you will forever be forgetting some class or throwing in the kitchen sink needlessly. There is automated help do select just the class files needed called genjar which works with ant, but, unfortunately, there is no corresponding tool to help with resources. However, there are ways of reducing the number of resource files (see Cramfull), and once you have the classes right, adding the corresponding resources is fairly mechanical.

Unlike zip files, the timestamps in jars created by jar.exe do not reflect the time the corresponding element file was last updated, but rather the time the element was added to the jar file.

Starting in JDK 1.5, you can super-compress jar files using pack200.exe. This will optionally remove debug information, and compress the jar as a whole.

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