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Introduction
JAR stands for Java ARchive, and its format is similar to that of zip files. The JAR file format is mainly used to combine a group of files into a single file. It's a single, cross-platform archive format for pictures, music, and class files.
It is backward compatible with the existing applet code. Jar files are written entirely in the Java programming language. We may obtain JAR files from the web or use the Eclipse IDE to create JAR files.
The JDK jar (Java Archive) tool allows you to build an executable jar file. When you double-click an executable jar file, it invokes the class's primary function. To build an executable jar file, you must first produce an a.mf file, also known as a manifest file.
How to Create a JAR File?
First make a .java file with a code in it, for example, we execute the following code: -
import javax.swing.*;
public class Classfile{
Classfile(){
JFrame f=new JFrame();
JButton b=new JButton("click");
b.setBounds(130,100,100, 40);
f.add(b);
f.setSize(300,400);
f.setLayout(null);
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new Classfile();
}}
You can also try this code with Online Java Compiler
Execute the code by opening the file, this in turn, results in formation of the class files in the same folder.
Make a text file and type the following and save it after pressing enter.
Main-Class: Classfile
Create a jar file using the instructions shown in the next section.
What is the Use of Jar Tools?
The Jar tools help in creating executable jar files using the jar tool.
The jar tool has many switches, for example,
-c: Heps in creating a new archive file.
-f Helps in specifying the archive file name.
-x Helps in extracting files from the archive file.
-v: Helps in generating verbose output and displays the included or extracted resource on the standard output.
-m includes manifest information from the given file.
Code to generate the executable jar file using CMD: -
It would be best if you wrote jar then switches then mf_file then jar_file then .classfile as given below:
jar -cvmf file_name.mf myjar.jar Classfile.class
What is the Importance of a JAR File?
A JAR (Java Archive) is a format for aggregating several Java class files and related information and resources (text, graphics, etc.) into a single file to distribute Java platform application software or libraries.
A JAR file is a compressed version.class files, audio files, picture files, or directories, in simple terms. A.jar file may be a compressed file (.zip) produced using WinZip software.
WinZip may also be used to extract the contents of the a.jar file. You may use them for lossless data compression, archiving, decompression, and archive unpacking, among other things.
Frequently Asked Questions
What is a JAR file?
JAR stands for Java ARchive, and its format is similar to that of zip files. The JAR file format is mainly used to combine a group of files into a single file. It's a single, cross-platform archive format for pictures, music, and class files. The JDK jar (Java Archive) tool allows you to build an executable jar file. When you double-click an executable jar file, it invokes the class's primary function.
How to Extract a JAR file?
Use the below-written code for extracting a JAR file:
jar xf jar_ filename
Where xf helps in extracting files from the jar files. For example, to extract the contents of a first.jar file, we can write: -
C:\> jar xf first.jar
This will create directories in C:\ META-INF
In this directory, we can see class_1.class and class_2.class.
How to update the JAR file content?
Use the code jar uf jar-file input-file(s) for updating a JAR file. Where 'uf' helps to update a jar file.
For example, to update the first.jar file, we can write: -
For example, to update the contents of our first.jar file, we can write: -
C:\>jar uf first.jar
How to run a JAR file?
Use the below-written code for running a JAR file: -
C:\>java -jar first.jar
What is the difference between a JAR file and a .exe file?
An .exe file is an executable file that may be run in the Microsoft Windows operating system. Jar files are containers for Java Class files and other project-related resources. Only the Java runtime environment is required to launch the Jar file. Multiple files can be bundled into a single file using the JavaTM Archive (JAR) file type.
Conclusion
In this article, we have extensively discussed Executable Jar Files in Java Swing and how to make them.
You can read Introduction to Java Swing for getting a good hold of the topic. After reading about the JAR files, are you not feeling excited to read/explore more articles on the topic of Programming in IoT and learning Ruby? Don't worry; Coding Ninjas has you covered. To learn, see more blogs on Ruby, Ruby Documentation, and Programming Language for IoT.
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