Try to invoke main class org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler manually

java -cp java-decompiler.jar org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler myclassfile.class .

Also you can find more about internal usage of Fernflower inside IDEA by query in source code https://github.com/JetBrains/intellij-community/search?utf8=%E2%9C%93&q=Fernflower

Answer from qwazer on Stack Overflow
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GitHub
github.com › fesh0r › fernflower
GitHub - fesh0r/fernflower: Unofficial mirror of FernFlower Java decompiler (All pulls should be submitted upstream)
java -jar fernflower.jar [-<option>=<value>]* [<source>]+ <destination>` ... <source>: file or directory with files to be decompiled. Directories are recursively scanned. Allowed file extensions are class, zip and jar.
Starred by 3.8K users
Forked by 699 users
Languages   Java
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Bytecode
the.bytecode.club › showthread.php
FernFlower - CLI Java Decompiler
java -jar fernflower.jar jarToDecompile.jar decomp/ With that fernflower will decompile jarToDecompile.jar and put the Java files into decomp/jarToDecompile.jar (Remember, jar is simply a .zip archive, so open it with any zip reader) If you run into the issue with people obfuscating as aa aA and you can't reobfuscate for some reason, fernflower has a neat ability that allows you to rename all of the classes/fields/methods to class1, class2, etc.
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YouTube
youtube.com › watch
How to create fernflower JAR and decompile Kotlin class to Java using a command line? - YouTube
fernflower is used internally by Intellij IDEA as a decompiler. If you have a use case to decompile Kotlin classes to Java using the command line, this video...
Published   April 21, 2021
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Jamie Tanna
jvt.me › posts › 2021 › 12 › 20 › java-decompile-command-line
Decompiling Java Class Files On the Command-Line · Jamie Tanna | Software Engineer
December 20, 2021 - You can either build it from the official IntelliJ repo or may find it more convenient to use the unofficial mirror of just the decompiler. This version includes the Main-Class attribute so you can execute it via: cd /path/to/source-repo # build the project java -jar build/libs/fernflower.jar <args>
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YouTube
youtube.com › wernerware
Fernflower Decompiler for Java - YouTube
Use Fernflower to decompile java code from .class and .jar files. This video shows you how to do it without IntelliJ Video notes: https://github.com/wernerwa...
Published   June 16, 2018
Views   5K
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Reddit
reddit.com › r/java › new open source java decompiler
r/java on Reddit: New open source Java decompiler
April 29, 2022 -

Hello! Today I'm happy to announce the release of a project that me and my friends have been working on over the course of the last year, Quiltflower! Originally intended just for use with the QuiltMC toolchain with Minecraft, Quiltflower quickly expanded to be a general purpose java decompiler aiming to create code that is as accurate and clean as possible. If the name sounds familiar it's because Quiltflower is a fork of Fernflower, the (in)famous decompiler that was developed by Stiver, maintained by Jetbrains, and became the default decompiler in Intellij IDEA. Fernflower also quickly found its way into many other tools. After many frustrations with it myself with its decompiled code structuring and quality I decided to do something about it, and here we are! Over the past year, Quiltflower has added support for features such as modern string concatenation, a code formatter, sealed classes, pattern matching, switch expressions, try-with-resources, and more. Quiltflower also focuses on the code quality of the decompiled output, and takes readability very seriously. We'd greatly appreciate it if you'd give it a try, with our Intellij Plugin, as a standalone jar, or on our maven. While it has come a long way it's still a work in progress, and feedback can be reported on our issue tracker.

Here's a comparison of Fernflower and Quiltflower's output.

I'd also like to thank the MinecraftForge Team for creating ForgeFlower, the fork that QuiltFlower was based on, and Lee Benfield for creating CFR and it's truly incredible test suite.

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Mkyong
mkyong.com › home › java › how to decompile class in java
How to decompile class in Java - Mkyong.com
July 1, 2021 - We no need to install or configure anything, just clicks on the Java class or method, clicks CTRL + B (declaration or usages) or CTRL + ALT + B (implementation), IntelliJ IDEA will automatically decompile the Java class.
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npm
npmjs.com › package › fernflower
fernflower - npm
Simple fernflower java decompiler wrapper. Latest version: 1.1.0, last published: 10 years ago. Start using fernflower in your project by running `npm i fernflower`. There are 1 other projects in the npm registry using fernflower.
      » npm install fernflower
    
Published   Apr 01, 2016
Version   1.1.0
Author   Romain Beaumont
Find elsewhere
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Eclipse Marketplace
marketplace.eclipse.org › category › free-tagging › fernflower
fernflower | Eclipse Plugins, Bundles and Products - Eclipse ...
Drag to your running Eclipse* workspace. *Requires Eclipse Marketplace Client ... Enhanced Class Decompiler integrates CFR, FernFlower, JD, Procyon, Vineflower seamlessly with Eclipse and allows Java developers to debug class files without source ...
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SoftTeco
softteco.com › home › java development › fernflower java decompiler
Fernflower Java Decompiler
July 3, 2025 - Fernflower is a really nice Java decompiler. It’s pretty convenient since you can decompile the whole JAR file.
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GitHub
github.com › JetBrains › fernflower
GitHub - JetBrains/fernflower: Decompiler from Java bytecode to Java, used in IntelliJ IDEA.
java -jar fernflower.jar -dgs=1 c:\Temp\binary\library.jar c:\Temp\binary\Boot.class c:\Temp\source\ Except for mpm and urc the value of 1 means the option is activated, 0 - deactivated. The default value, if any, is given between parentheses. Typically, the following options will be changed by user, if any: hes, hdc, dgs, mpm, ren, urc The rest of options can be left as they are: they are aimed at professional reverse engineers.
Starred by 4.1K users
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Languages   Java
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JetBrains
youtrack.jetbrains.com › issue › IDEA-175638 › Please-release-fernflower-decompiler-as-a-standalone-jar
Please release fernflower decompiler as a standalone jar
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CodingTechRoom
codingtechroom.com › question › ferflower-java-decompiler-guide
How to Utilize Fernflower Java Decompiler Effectively? - CodingTechRoom
Fernflower is a powerful open-source Java decompiler that converts compiled Java bytecode (.class files) back into human-readable Java source code. This guide provides a comprehensive overview of how to effectively utilize the Fernflower decompiler, as well as common issues and their solutions. ... // Example command to use Fernflower java -jar fernflower.jar input_class_file.class output_directory
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GitHub
github.com › MinecraftForge › FernFlower › issues › 1
How do you build the fernflower.jar? · Issue #1 · MinecraftForge/FernFlower
January 23, 2017 - You mention using the fernflower.jar, but I cannot seem to find it in this repo. I assume I have to build it, but again there are no instructions on how to do that. I am not a java developer so it ...
Published   Apr 27, 2017
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Fxis.ai
fxis.ai › home › how to use fernflower: the analytical decompiler for java
How to Use Fernflower: The Analytical Decompiler for Java fxis.ai
September 28, 2023 - This blog post will guide you through using Fernflower, including command-line operations, customizing options, and troubleshooting tips. Before diving into operation specifics, you’ll need to download Fernflower and ensure you have Java installed on your machine.
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GitHub
github.com › 6168218c › FernflowerUI
GitHub - 6168218c/FernflowerUI: The fernflower decompiler with GUI.
Search for some contents in Current Block,Current Document,All Open Documents,Current Package and The Whole Jar with the FindText dialog box.You can press Control to make the dialog box transparent.
Starred by 109 users
Forked by 21 users
Languages   C++ 82.6% | C 17.4%
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Studytonight
studytonight.com › java-examples › how-to-decompile-java-classes
How to Decompile Java Classes - Studytonight
Go to Window > Preferences > General > Editors > File Associations, and select the "*.class without source" option. Select Class Decompiler Viewer as the default for it, and apply the changes.