How is GCJ different from Sun Java?

Rui Wang
Tue Nov 8 16:39:00 GMT 2005

Hi Ernesto, 

I am not GCC expert in fact I just got into GCJ. But I will try my best to answer your questions. 
If any GCC guru is listening, feel free to correct me if I am wrong. 

The answer to your first question depends on what you really were asking. If you are asking about GCJ package including libgcj, then gcj is GNU version of JVM. libgcj is like SUN's sdk. The differences are GNU is free and open source but sun's JVM is not. you can use it to compile your regular java applications for sure. However, the downside is that there are a few areas need improvements and need to update from time to time. From my own experience, RMI is certainly not working that smooth. If you are asking about gcj compiler is self, then you can do many different cool things with it, not only just compile your .java files to .class file, but also compile your .java files to native code(.exe files on windows) and compile .class file to native code. 

I don't think you can "mix and match" sun's libraries with GUN's. But gcj cetainly support swing utils (there might be bugs need fix, but I would say it's in a reasonable state). 

Not entirely sure I understand what you are asking in your third question. 


-----Original Message-----
From: on behalf of Ernest L. Williams Jr.
Sent: Tue 11/8/2005 4:27 PM
To: GCC-Help
Subject: How is GCJ different from Sun Java?

Can someone explain what is the gcj in the GCC software?
How is it different from Sun Java?

Does gcj need a jvm? Does the jvm come from GNU?

Can we mix and match java libraries from SUN and GNU?
Does gcj have a good graphics library (e.g. swing)?

Is gcj completely compliant with SUN's definition of java?

All of these questions were generated when I started running "Native
Eclipse" on Fedora Core 4.


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