I suggest you to do this only it if it is your application or if you have the author's permission. 🙃 Procedure Warning: decompiling, or reverse engineering, a part of an application seems to fall into gray areas, depending of the jurisdiction. So, if you really want to protect your intellectual property, I suggest you choose another language and above all, host your application yourself. I tried one of them in the second part of this post, but the results seem to vary from project to project. Do you see any other differences? 🤨Ĭomparison of the source code with its decompiled version in IntelliJ IDEA.Įven if you don't have an IDE that can decompile a class file for you, other solutions allow you to achieve this goal. All comments have been removed along with some final keywords. If you look at the following images, you will see that there is not much difference between the source code and its decompiled version. If you look at the same file with your IDE, some of them, like Intellij IDEA, can even decompile this type of file for you! 😮 An example of the content of a class file. Ouch!, you weren't expecting to see these files, right? At least, they're still unusable, for now.

and the structure of your application with its files as *.class format.

the list of dependencies along with their respective version.

the framework and its version: Spring-Boot-Version: 2.4.4.

If you rename the file as APPLICATION.zip and extract the archive, you should see a few folders there, which contain a lot of interesting files. 😟 Effectively, the Jar file is in reality a simple Zip file with another extension. Unfortunately, if you think your source code is completely opaque, you are mistaken. 🤖 An example of the content of a Jar file. If you open this file, you will see that the file is incomprehensible to you, unless you are a robot. Once compiled, an executable Jar file is created (like APPLICATION.jar). With Gradle, one of the commands that do this is gradle assemble. If you write Java applications, you may already know that, to be able to easily use your application on another computer, you need to compile its source code.

Simple java projects with source code