1. Executable Jars
Dan Fleck
Fall 2007
12/27/2018

2. Introduction
Executable Jars allow a program to be packaged and run more simply
Today’s Agenda
How to run Java Programs
How to Create Executable Jars
12/27/2018

3. How to Run Java Programs
Assume we are in directory:
C:\javacode\myprojects\cls
Contents of that directory are:
MyClass.class
Shape.class
Ball.class
edu\
Utils.class
Elephant.class
gmu\
Ball.jpg
Elephant.jpg
Sphere.gif
pack1\
pack2\
images\
12/27/2018

4. How to Run Java Programs
C:\javacode\myproject\cls\
edu
How to Run Java Programs
gmu
Run using the classes cd to directory C:\javacode\myprojects\cls java edu.gmu.pack1.MyClass
Run using the classpath java -cp c:/javacode/myproject/cls edu.gmu.pack1.MyClass
Run using the the Jar java -cp myjar.jar edu.gmu.pack1.MyClass
Run using an executable Jar java -jar myexecutablejar.jar
pack1
pack2
images
12/27/2018
Executable Jars are the easiest! (Less thinking!)

5. How to Create a Jar C:\javacode\myproject\cls\ edu gmu pack1
cd to the top level directory of your package. (c:\javacode\myproject\cls)
Create it jar cvf myjar.jar * c = create new archive v = verbose output f = archive file name
Check it! jar tvf myjar.jar t = display table of contents
pack2
images
12/27/2018

6. How to Create a Jar C:\javacode\myproject\cls\ edu gmu pack1
Try running it! java -cp myjar.jar edu.gmu.pack1.MyClass
pack2
images
12/27/2018

7. Question C:\javacode\myproject\cls\ edu gmu pack1
Question: What did java need to know in order to run the program?
java -cp myjar.jar edu.gmu.pack1.MyClass
Answer: Which class is the main-class! java -cp myjar.jar edu.gmu.pack1.MyClass
pack2
images
An executable Jar just needs to know the main-class in order to run!
12/27/2018

8. Creating the executable jar
C:\javacode\myproject\cls\
edu
Creating the executable jar
gmu
pack1
cd to the top level directory of your package. (c:\javacode\myproject\cls)
Create a manifest text file that holds the main-class: Notepad mymanifest Manifest-Version: 1.0 Main-Class: edu.gmu.pack1.MyClass
Create the jar with -m option: Jar cvfm myjar.jar mymanifest * m = use specified manifest
pack2
images
12/27/2018

9. Creating the executable jar
C:\javacode\myproject\cls\
edu
Creating the executable jar
gmu
pack1
Test it:
java -jar myjar.jar
pack2
images
12/27/2018

10. Advantages Jars make code more portable by keeping it all together
Executable jars make the code easier to run Note: On some systems (Windows, some Unix variants) Jar files are associated with the “java -jar” command, so simply double-clicking on an executable Jar will run it.
12/27/2018