Re: WTF: All those eclipse packages (and som gcj questions)
On 17.12.05 13:28:27, Michael Koch wrote:
> On Sat, Dec 17, 2005 at 12:09:08PM +0100, Andreas Pakulat wrote:
> > On 17.12.05 12:20:53, Michael Koch wrote:
> > > On Sat, Dec 17, 2005 at 01:59:54AM +0100, Andreas Pakulat wrote:
> > > > Hi,
> > > >
> > > > I do find it really great to have eclipse in debian (finally). Only I'm
> > > > a little confused by all those new packages. So here come my questions,
> > > > please someone shed some light on this:
> > > >
> > > > 1. Do I understand correctly that the "ecj" is a java 1.3/1.4 compiler
> > > > that I can get either as "pure-java-version" (via eclipse-ecj) or as
> > > > native binary (via eclipse-ecj-gcj). What benefits has ecj above gcj?
> > >
> > > ECJ from Eclipse 3.1.x is a Java 5.0 compliant compiler. It can handle
> > > all language enhancements of Java 5.0. GCJ 4.0 and the upcoming 4.1
> > > cannot handle Java 5.0 stuff. They are more or less Java 1.4 compliant
> > > with support for some classes from 5.0 but no language extensions.
> > > GCJ can produce bytecode OR native code. ECJ can only produce bytecode.
> > > A natively compiled ECJ is mostly faster in producing byecode than GCJ.
> > Hmm, how could I benefit from ecj from within eclipse? I mean, what do I
> > need to change in the preferences so that Eclipse uses ecj-gcj to
> > compile java classes?
> Only when using GCJ to run Eclipse and eclipse-ecj-gcj is installed.
Ok, got that installed.
> Eclipse just calls the main ECJ class inside itself and SUN is not
> capable of using the native jars.
Hmm, so when running eclipse with gcj it automatically uses ecj-gcj when
the eclipse-ecj-gcj package is installed?
I just want to be sure I get this right.
> > > > 2. Those eclipse-* packages that have a eclipse-*-gcj counterpart: Is
> > > > the gcj-version (i.e. natively compiled plugins) faster? What are their
> > > > benefit above the normal variant?
> > >
> > > When running eclipse with GCJ eclipse is much faster when the
> > > eclipse-*-gcj packages are installed because GCJ only integrates a
> > > simple interpreter, no JIT, and it can run the native code then.
> > Hmm, that raises another question: How to do that? I can of course
> > changed the java/javac alternatives to gcj but I'd like to leave the
> > default java to be SUN's. Now specifying JAVA_HOME to be /usr doesn't
> > work either, eclipse still uses "java" to execute. Using /usr/lib/jvm as
> > JAVA_HOME gives an error message from eclipse telling me it's missing a
> > binary.
> You can use /usr/lib/jvm/java-gcj as JAVA_HOME. When java-gcj-compat is
> install there is a complete JRE. When java-gcj-compat-dev is installed
> too there is a complete SDK.
Thanks, that works very well...
Give him an evasive answer.