Can't get Java to work and don't know if I should persue it.

Travis86 · 12-10-2003, 11:19 AM

I don't know if this should be two threads or not, but I'm making it one.

First I got the Java SDK 1.4.2 and installed it (on Windows, BTW) and now I'm trying to get my first program to work. I copied it right out of my book, Learning Java (from O'Reilly), and it is as follows:

Code:

public class Pre {
    public static void main( String[] args ) {
	System.out.println("Hi, everyone.");
    }
}

I run "C:\j2sdk1.4.2_02\bin\javac Pre.java" and it works (I haven't bothered to set the path to include the Java bin directory). When I run "C:\j2sdk1.4.2_02\bin\java Pre" it thinks for a while and says "Exception in thread "main" java.lang.NoClassDefFoundError: Pre/Java". Can anyone tell me what's going wrong here?

Also, in Learning Java, the author seems to think that Java is the greatest thing ever. I assume he's a bit biased, but I figured I'd find out whether this was true on my own.

I was using NetBeans, which was written entirely in Java, and I don't think I've ever used a slower program in my life. From what I understand of Java, the JVM code is being compiled "Just In Time." My diagnosis for NetBeans is that it's a decent program in need of good, old-fashioned compiling. I know I don't have a fast computer, but Photoshop runs twice as fast as NetBeans. Every time that I would go to another program and come back to NetBeans the hard drive would go into overdrive and it would freeze. Even during normal use the hard drive hardly ever stopped cranking. And nothing ran smoothly.

Is Java really all its supposed to be?

deiussum · 12-10-2003, 01:55 PM

You might have to add the current directory to your CLASSPATH. Try either adding ./ to your CLASSPATH environment variable, or find out what the command-line option is to add a CLASSPATH directory. I believe the parameter for that was -cp...

About the slowness of the IDE. I've noticed that myself. Not only with the NetBeans IDE, but also with Borland's IDE, which is also written in Java. That's just one of the reasons I generally don't develop stuff in Java myself.

Travis86 · 12-10-2003, 09:48 PM

That was the problem, alright! Works like a charm now. Well, like a slow charm, anyway.

I found that the Java part of the GCC will compile Java right into machine code (see http://gcc.gnu.org/java/). I think that's probably the way to go, although it's against almost everything Sun wants Java to be. I guess they'll have to get over it.

memory_leak · 12-11-2003, 09:49 AM

Code:

That was the problem, alright! Works like a charm now. Well, like a slow charm, anyway.

I found that the Java part of the GCC will compile Java right into machine code (see http://gcc.gnu.org/java/). I think that's probably the way to go, although it's against almost everything Sun wants Java to be. I guess they'll have to get over it.

oh man - let's be hones: you can't see speed difference in byte compiled code and machine code when you run THAT program

ofcourse is java slower than machine code - but you need a way muuuuch more compilacated applications to see that difference