"jar --main-class" - Making JAR File Executable

This section provides a tutorial example on how to use 'jar --main-class ...' command option to specify the application main class to make a JAR file executable.

You can also make a JAR file "executable", if you:

Here is what I did to add my JAR file, herong.jar, executable using the "jar --update --main-class ..." command:

herong> jar --update --verbose --file herong.jar --main-class F2C

updated manifest

Now herong.jar contains a small stand-alone application. But how to execute this JAR file? That's easy. You can run a JAR file with the "java -jar" command like this:

herong> java -jar herong.jar 60.0
Fahrenheit = 60.0
Celsius = 15.555555555555555
My TempraturConvertorBean - Version 1.00

Cool. Right? But you can make it even better. You can register JAR files to be automatically opened by the "java -jar" command on Windows system to make JAR files "truly" executable. Here is what I did to make this happen.

Warning: this following tutorial modifies Windows registry database. Please do not follow it if you don't have enough knowledge about Windows system.

1. Go to Start > Run. And enter "regedit" followed by clicking OK. Registry Editor window shows up.

2. Go to [HKEY_CLASSES_ROOT\jarfile\shell\open\command]. You should see the current value like this: ("C:\Program Files\Java\jdk-17.0.1\bin\javaw.exe" -jar "%1" %*). This was added when you install JDK on your system.

3. Double click this value and change it to: ("C:\Program Files\java\jdk-17.0.1\bin\java.exe" -jar "%1" %*).

4. Open a command window and try this:

herong> herong.jar 50

Fahrenheit = 50.0
Celsius = 10.0
My TempraturConvertorBean - Version 1.00

Better. Right? You can run any JAR files by just typing their file names now.

You can also double click any JAR files on Window Explorer now. Try it and see what happens.

Table of Contents

 About This Book

 Java Tools Terminology

 Java Tools Included in JDK

 javac - The Java Program Compiler

 java - The Java Program Launcher

jar - The JAR File Tool

 JAR - Java Archive File Format

 jar - JAR File Tool Command and Options

 "jar --create" - Creating New JAR File

 "jar --list" - Listing Files in JAR File

 "jar --extract" - Extracting Files from JAR File

 Managing JAR Files with WinZIP



 "jar -C" - Changing Input Directory

 Using JAR Files in Java Class Paths

 "jar --update" - Updating Class Files in JAR

"jar --main-class" - Making JAR File Executable

 Creating Module JAR File

 "jar --module-version" - Updating Module Version in JAR

 jlink - The JRE Linker

 jmod - The JMOD File Tool

 jimage - The JIMAGE File Tool

 jpackage - Binary Package Builder

 javadoc - The Java Document Generator

 jdeps - The Java Class Dependency Analyzer

 jdeprscan - The Java Deprecated API Scanner

 jdb - The Java Debugger

 jcmd - The JVM Diagnostic Tool

 jconsole - Java Monitoring and Management Console

 jstat - JVM Statistics Monitoring Tool

 JVM Troubleshooting Tools

 jhsdb - The Java HotSpot Debugger

 jvisualvm (Java VisualVM) - JVM Visual Tool

 jmc - Java Mission Control

 javap - The Java Class File Disassembler

 keytool - Public Key Certificate Tool

 jarsigner - JAR File Signer

 jshell - Java Language Shell

 jrunscript - Script Code Shell

 Miscellaneous Tools

 native2ascii - Native-to-ASCII Encoding Converter

 JAB (Java Access Bridge) for Windows

 Archived Tutorials


 Full Version in PDF/EPUB