Minecraft: Java Edition has been obfuscated since its release. This obfuscation meant that people couldn’t see our source code. Instead, everything was scrambled – and those who wanted to mod Java Edition had to try and piece together what every class and function in the code did.
Modding is at the heart of Java Edition – and obfuscation makes modding harder. We’re excited about this change to remove obfuscation, as it should make it quicker and easier for modders to create and improve mods. Now you won’t have to untangle tricky code or deal with unclear names. What’s more, de-bugging will become more straightforward, and crash logs will actually be readable!
surprisingly fantastic and consumer friendly move from mojang, good on them
You can use tools like FernFlower to help turn that bytecode into actual Java.
Indeed - most Java IDEs have FernFlower built in, so it’s dead easy.
Decompiled Java is surprisingly close to the original, especially compared to eg. decompiled C++; good luck with that. You get all the class, function and variable names back on the original line numbers.
What you do not get back is any comments. So you can see what and how, but not why. Admittedly, most comments are kind of useless and do not explain ‘why’ very well, but for weird-but-critical code they can be essential.