Is Java a compiled language? How does the Java Runtime Evrionment do anything then, since if Java is compiled, there will be binary files. Right?

Also, whats the relation between Java and Javascript?

Java is compiled into byte code, which is then interpreted by the Java Virtual Machine (JVM).

There are also "Just in Time" compilers which, instead of interpreting and executing the byte code, compile the byte code into native code and pass it to the OS for execution.

In addition to the byte code from your own classes, Java also provides its own built-in classes. You can consider the combination of JVM (byte code interpreter) + all the standard runtime classes as the "Java Runtime Environment" (JRE).

When someone executes your Java program, they need a (JRE == ((JVM || JIT) + standard run-time classes)).

All of the above, of course, is also pretty much 100% applicable to .NET.

And none of it's applicable to JavaScript. Netscape changed the name from "LiveScript" to "JavaScript" at the last minute, for purely marketing reasons. Java and Javascript have little or nothing in common, except the name and except for somewhat C-like syntax.

what is byte code? is it programmer readable? Why would one do programming this way as opposed to straight binary code(a la C, C++)?

"Portability" is the big reason.

Other benefits include the ability to dynamically load at the class-level (instead of just at the library level), the possiblity of real-time ("Hotspot") performance optimization and (another biggie) automatic memory management/garbage collection. Compactness (especially important for distributed/web based apps), security (ditto) and flexibility (another variation of the "dynamic loading" argument) come to mind.

Again, the pros/cons for Java are almost indistinguishable from the pros/cons of .NET.

Here are some links that might help:

http://en.wikipedia.org/wiki/Bytecode

http://cem.colorado.edu/archives/fl1997/matt.html

http://docs.msdnaa.net/ark/Webfiles/WhitePapers/CLR.pdf

http://www.unix.org.ua/orelly/java-ent/jnut/ch01_02.htm

Byte code is machine readable, not human readable. One of the main reasons for doing it is to abstract away the OS specific stuff so that code compiled on one platform, can run on any platform that the JVM will run on. Because the JVM takes care of memory management, it also removes the need for things like pointer manipulation.

I'm generalising - of course there are exceptions and disadvantages in the real world, but it has worked well on many of the projects I've been involved in.

Java bytecode is instructions for the Java virtual machine, which is kind of like machine code, but more abstract. It has the advantages that it is compiled, so that it only represents the instructions and so many languages can be compiled to it; while at the same time it is not specific to any specific processor or machine architecture, but can easily and quickly be run on any processor architecture using the Java virtual machine.

so Java is compiled though(or at least, kind of compiled)? Are there open-source "compilers" for linux? or do we have to use Suns'?

Yes, there are:
* GCJ
* Jikes
But some new Java features might not be supported

And don't forget the Kaffee JVM:
http://www.kaffe.org/

or the Blackdown compiler:
http://www.blackdown.org/

I would argue that Sun has done a pretty decent job of balancing making Java an "open" standard, yet keeping it stable and well managed.

Ok, thanks. I was mostly curious, seeing as I'm planning on being a CS major, and Java is pretty prevalent.

Here are two links you might want to check out:

http://www.tiobe.com/tpci.htm

http://www.dedasys.com/articles/lang...opularity.html

Neither of these sites necessarily *mean* anything in terms of the question "which programming language will be of most use to me five years from now?", or even "should I be a CS major ... or go into Business ... or French Literature?" But they're definitely both interesting reading ;-)

Happy New Year .. PSM