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Decompiling Java Class Files

Anu Pillai

Joined: Oct 09, 2006
Posts: 28
Is there any way to decompile a class file to get the Java code without using any software like DJ Decompiler etc.
Jim Yingst

Joined: Jan 30, 2000
Posts: 18671
Well, I'm not sure how you'd even read the bytes of the class file without some sort of "software". It's tempting to start to list hopelessly impractical and silly low-level procedures for doing this. But to save time, I'll assume you're willing to at least use basic tools provided with Sun's own JDK - namely, javap. You can use this to convert a class file to a sort of assembly language for the JVM, which is described in the JVM Specification. It's possible to look through this carefully and, using your own brain, figure out what a program is doing. Unfortunately it's also slow and tedious, and error-prone for most of us. Which is why people developed programs like JAD. So I'd say yes, it's possible - though I'm not sure why anyone would want to.

"I'm not back." - Bill Harding, Twister
Anu Pillai

Joined: Oct 09, 2006
Posts: 28
Thanks Jim,

The thing is that I need to look at the source code of a class to debug a partcular issue and I dont have the Java File. And I am unable to download anything from the internet. Thats why I insisted on getting the class file without using any software. I thought that there would be something available in the JDK. Thanks for the info.
Stephen Foy
Ranch Hand

Joined: Oct 17, 2005
Posts: 143

Seems to decompile class files. However, if you want to decompile exe files, the only source code you will get is in assembler.

Stephen Foy - Microsoft Application Development Consultant
I agree. Here's the link:
subject: Decompiling Java Class Files
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