Let us see how to create a
JAR file using
Java’s jar command as well as using
Eclipse IDE. The JAR file format is based on the popular ZIP file format. Usually these file are used for archiving and distribution the files and implementing various libraries, components and plug-ins in java applications. Compiler and JVMs (Java Virtual Machine) can understand and implement these formats for java application.
Create a JAR file
| jar cf JAR_FILE_NAME FILE_NAMES_OR_DIRECTORY_NAME
Eg:
jar cf MyApp1.jar C:\MyProject\MyApp
|
View contents of a JAR file
|
|
| jar tf JAR_FILE_NAME
e.g.
jar tf MyProject.jar
|
View contents with detail of a JAR file
| jar tvf JAR_FILE_NAME
e.g.
jar tvf MyProject.jar
|
Note that we have used
v (verbose) option to see the detail of JAR.
Extract content of JAR file
| jar xf JAR_FILE_NAME
e.g.
jar xf MyProject.jar
|
Extract specific file from JAR file
| jar xf JAR_FILE_NAME FILE_NAME(S)_FROM_JAR_FILE
e.g.
jar xf MyProject.jar Test1.class
|
Update a JAR file
| jar uf JAR_FILE_NAME FILE_NAMES_FROM_JAR_FILE
e.g.
jar uf MyProject.jar Test1.class
|
Executing a JAR file
| java -jar JAR_FILE_NAMEe.g.
java -jar MyProject.jar
|
Create an executable JAR file
In order to create an executable JAR, one of the classes that we include in our JAR must be a main class.
Create a text file called
MANIFEST.MF using any text editor and copy following content in it.
| Manifest-Version: 1.0
Main-Class: MyMainClass
|
Where MyMainClass is the name of the class that contents main method. Also note that you have to specify fully qualified class name here.
Use following command to create an executable JAR file.
| jar cvfm MyProject.jar MANIFEST.MF FILE_NAMES_OR_DIRECTORY_NAME
|
