Creating an Executable jar File
In Java, it is common to combine several
classes in one .jar ("java archive") file.
Library classes are stored that way.
Larger projects (such as the Case Study in the AP program) use jar files.
You can create your own jar file combining several classes, too.
jar files are created using the
jar.exe utility program from
You can make your jar file runnable by telling
To do that, you need to create a manifest file.
A manifest is a one-line text file with a "Main-Class" directive.
This line must end with a newline.
A jar file created with a main class manifest can be used both
as a library and a runnable jar.
If you use it as a library, you can edit and compile
any of the classes included in the jar, and add it to
Then it will override the one in the jar file.
You can create a manifest file in any text editor,
or even by using the MS-DOS
You can give your manifest file any name, but it's better
to use something standard, such as
Once you have a manifest and all your classes
have been compiled, you need to run JDK's
It is located in the JDK’s
bin folder, the same place
jar.exe takes command-line arguments;
if you run it without any arguments, it will
display the usage information and examples.
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
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 the
command line, using the
e switch, instead of
Then you do not need a separate manifest file;
add the required manifest to your jar file for you.
C\mywork> jar cvfe MyJarName.jar MyMainClass *.class
Below is a reference for creating a jar file in Eclipse
and the detailed steps for doing this
in Command Prompt and in JCreator.
Creating a jar File in Eclipse
In Eclipse Help contents, expand "Java development user guide" ==>
"Tasks" ==> "Creating JAR files."
Follow the instructions for "Creating a new JAR file"
or "Creating a new runnable JAR file."
JAR File and
Runnable JAR File commands
are for some reason located under the
Export... and expand the
Creating a jar File in JCreator
You can configure a "tool" that will automate the jar creation process.
You only need to do it once.
- Click on
- Click on
Tools in the left column.
New, and choose
Create Jar file.
- Click on the newly created entry
Create Jar File
in the left column under
- Edit the middle line labeled
it should have
cvfm $[PrjName].jar manifest.txt *.class
- Click OK.
Now set up a project for your program,
create a manifest file
manifest.txt or copy
and edit an existing one.
manifest.txt in the same folder
.class files go.
Click on the corresponding tool button or press
Ctrl-n if this is the n-th tool)
to run the
Create Jar File tool.
With Windows Explorer, go to the jar file
that you just created and double click on it to run.
Creating a jar File in Command Prompt
- Start Command Prompt.
- Navigate to the folder that holds your class files:
- Set path to include JDK’s bin.
C:\mywork> path c:\Program Files\Java\jdk1.7.0_25\bin;%path%
- Compile your class(es):
C:\mywork> javac *.java
- 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 cvfe Craps.jar Craps *.class
- Test your jar:
C:\mywork> java -jar Craps.jar