- In Java, it is common to combine several classes in one .jar ("java archive") file.
- Library classes are stored that way.
- jar files are created using the
jar.exe
utility program from JDK. You can make your jar file runnable by tellingjar.exe
which class hasmain
. To do that, you need to create a manifest file. A manifest is a one-line text file with a "Main-Class" directive. For example:
Main-Class: Craps
This line must end with a newline.
- You can create a manifest file in any text editor, or even by using the MS-DOS
echo
command. You can give your manifest file any name, but it's better to use something standard, such asmanifest.txt
. - Once you have a manifest and all your classes have been compiled, you need to run JDK's
jar.exe
utility. It is located in the JDK’sbin
folder, the same place wherejavac.exe
andjava.exe
are.jar.exe
takes command-line arguments; if you run it without any arguments, it will display the usage information and examples.You need
C\mywork> jar cvfm MyJarName.jar manifest.txt *.class
cvfm
means "create a jar; show verbose output; specify the output jar file name; specify the manifest file name." This is followed by the name you wish to give to your jar file, the name of your manifest file, and the list of.class
files that you want included in the jar.*.class
means all class files in the current directory.
- Actually, if your manifest contains only the Main-Class directive, you can specify the
main
class directly on thejar.exe
's command line, using thee
switch, instead ofm
. Then you do not need a separate manifest file;jar
will add the required manifest to your jar file for you. For example:
C\mywork> jar cvfe MyJarName.jar MyMainClass *.class
💜 The detailed steps for creating a jar file in command prompt :
'
1. Start Command Prompt.
2. Navigate to the folder that holds your class files:
C:\>cd \mywork
3. Set path to include JDK’s bin. For example:
C:\mywork> path c:\Program Files\Java\jdk1.7.0_25\bin
4. Compile your class(es):
C:\mywork> javac *.java
5. Create a manifest file and your jar file:
C:\mywork> echo Main-Class: Craps >manifest.txt
C:\mywork> jar cvfm Craps.jar manifest.txt *.class
C:\mywork> jar cvfm Craps.jar manifest.txt *.class
or
C:\mywork> jar cvfe Craps.jar Craps *.class
6. Test your jar:
C:\mywork> Craps.jar
or
C:\mywork> java -jar Craps.jar
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