[2283] in java-interest
java-interest-digest V1 #191
daemon@ATHENA.MIT.EDU (owner-java-interest-digest@java.su)
Wed Sep 27 22:49:03 1995
From: owner-java-interest-digest@java.sun.com
Date: Tue, 26 Sep 1995 23:30:10 -0700
To: java-interest-digest@java.sun.com
Reply-To: java-interest@java.sun.com
java-interest-digest Wednesday, 27 September 1995 Volume 01 : Number 191
In this issue:
problems with animator applet
Re: Java SIG in NYC
Sending an object across the net...
IMPORTANT: Registration information for Java Courses
Re: JDK : layout : is something wrong ?
Re: Ready or not, here it comes...
Re: throws declataration in Java/beta
Resend: Re: Debugging Java
Re: Setting Boundaries (was Re: JDK Question)
Re: regular expressions in Java
Java Progress and the Java team
Java Grammar
Re: throws declataration in Java/beta
Re: throws declataration in Java/beta
Re: Sending an object across the net...
Java VM clarifications
Re: GUI design
----------------------------------------------------------------------
From: Dorian Winterfeld <dorian@Glue.umd.edu>
Date: Tue, 26 Sep 1995 19:49:49 -0400 (EDT)
Subject: problems with animator applet
Dear Java Gurus.
I am a novice Java programmer who is struggling to get the new
Animator class to work. I incorporated the following code into my html:
<app class="Animator" img="gifs" pause=0 repeat=true audioloops=true
audio="spacemusic.au">
And tried to view it via HotJava but it doesn't work! Nothing happens.
I created a directory called classes and put Animator.class in it. I
renamed my gifs to T1.gif to T9.gif and placed them in a directory
called gifs. I put the .au file in the same directory as my html.
Am I doing something wrong ? BTW, I compiled Animator.java on ver 1
Alpha3 of HotJava under Win95. Can anyone help me out?
my URL is http://www.wam.umd.edu/~dorian/index.html.
------------------------------
From: Andrew Zolli <sgint2@interport.net>
Date: Tue, 26 Sep 1995 19:50:37 -0400 (EDT)
Subject: Re: Java SIG in NYC
On Tue, 19 Sep 1995, Timothy Arnold wrote:
> Hi java programmers,
>
> Well its happening. After getting a very positive response about starting a
> java programming Special Interest Group here in New York City, I'm going to
> proceed on and try to schedule a meeting within a week or so. I'll replay
> the message I posted at wwwac in NYC and let me know if you are interested.
> _______________________________________________________________________________
> Hello wwwac members,
>
> I'd like to start a SIG group centered on programming in Java. In order to
> benefit developers I'd also like to keep it focussed on programming issues
> to help current programmers troubleshoot, figure out semantics, or just get
> started in this new language. My motivation for this is to speed up the
> learning curve and to at least start a network of fellow java programmers in
> NYC which would benifit all of us. If you think you might be interested
> please let me know and I will repost within a week so we can get the ball
> rolling.
>
> Best Regards,
> Tim Arnold
> yimmit@well.com
> ____________________________________________________________________________
> ____
>
> -
> Note to Sun employees: this is an EXTERNAL mailing list!
> Info: send 'help' to java-interest-request@java.sun.com
>
There already IS a Java Users Group in NYC... its first meeting was
announced by Olivia Whiteman at Java Day... If anyone needs info, please
get in touch.
Andrew Zolli
Webmaster,
Siegel & Gale
NYC
------------------------------
From: Derek Hamner <dhamner@email.unc.edu>
Date: Fri, 22 Sep 1995 14:34:54 -0400 (EDT)
Subject: Sending an object across the net...
I have written simple client & server based on the sun.net classes and I
would like to know if it would be possible to extend the
DataInput/OutputStream classes to accommodate more complex types. I
would like to be able to send any simple object across the network, and
then reconstruct it on the other side. Is this possible?
Any help or pointers to past discussions on this topic would be greatly
appreciated.
Derek Hamner
UNC-Chapel Hill
------------------------------
From: tmcg@blueline.East.Sun.COM (Tom McGinn - SunService Education)
Date: Fri, 22 Sep 1995 15:39:56 -0400
Subject: IMPORTANT: Registration information for Java Courses
***** FOR FURTHER INFORMATION ABOUT REGISTERING FOR JAVA TRAINING: *****
Folks -
Sorry for the confusion. There are two registration phone numbers;
one for International students and one for US students.
International students (Outside of the US) please use call:
(408) 276-3630 for registration information (8 am to 5 pm PST).
or send e-mail with a request for information to: registrars@sun.com
In the US, please call:
(800) 422-8020 for registration information (8 am to 5 pm PST).
Sun Microsystems students should register using e-mail. Please send
e-mail to (no subject required): education@sun.com
------------------------------
From: reast@esri.com (Russell East [ESRI-Redlands])
Date: Tue, 26 Sep 95 15:52:23 PDT
Subject: Re: JDK : layout : is something wrong ?
: Hi Jean-Claude,
:
: > I cannot get anything deterministic out of the various
: > layoutManagers. Is something wrong, or is it just me ?
:
: I hope it is just you. If you have a particular problem you'll have
: to attached a simple example. Random muttering doesn't help.
:
: Arthur van Hoff
Maybe you are having the same problem that I am experiencing?
I am using a Solaris 1 machine operating as an X-terminal onto
a Solaris 2 system where all the java work is done. When running
appletviewer (Beta1) or hotjava (Alpha3) on my Sol1 system, if I
drag any window corner out, the layout does not correctly
compensate for the window resize, and the graphics moves all over
the place - if I drag the window size far enough, the graphics
completely disappears.
I don`t get this problem when running on a Sol2 X console, nor on
my NT box operating as an Xterminal. I guess it's time for an
upgrade for me.... :)
Russell.
- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
ESRI| | Russell East,
| | Development Programmer E-mail: reast@esri.com
----|---| Environmental Systems Research Institute
| | 380 New York Street Voice : +1 (909) 793 2853
____|___| Redlands, Ca, 92373, USA Fax : +1 (909) 793 5953
- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
------------------------------
From: Sami.Shaio@Eng.Sun.COM (Sami Shaio)
Date: Fri, 22 Sep 1995 11:14:34 -0700
Subject: Re: Ready or not, here it comes...
A number of us in the Java group have been involved with helping
Netscape do the Java integration. As a result we know exactly what's
going on. To restate what has been said by arthur: *only* the java
applet support has any relation to Java, everything else including
their scripting language has *no* relation. Trust me.
- --sami
|From phil@bolthole.com Wed Sep 20 18:45:13 1995
|Subject: Re: Ready or not, here it comes...
|To: java-interest@java
|Date: Wed, 20 Sep 1995 11:18:44 -0700 (PDT)
|From: phil@bolthole.com (Philip Brown)
|Mime-Version: 1.0
|Content-Transfer-Encoding: 7bit
|X-Info: To unsubscribe, send 'unsubscribe' to java-interest-request@java.sun.com
|
|[ Glen C. Perkins writes ]
|>
|>
|> I wasn't guessing that the plug-ins were *written* in Java, I was guessing
|> that they could be *driven* from Java. I know they're not written in Java.
|
|You KNOW they are not?
|
|Personally, I was hoping that netscape had put a layer on top of java, to
|create their own "java for idiots" language, that is a cross between java,
|perl, and logo. It would then have hooks to call plugins.
|The plugins would presumably be standalong C-compiled things. Although if
|they are being nice, plugins should also be ALLOWED to be java code as well.
|
|Access to plugins could be done through some security module, like file and
|host access is handled with hotjava.
|-
|Note to Sun employees: this is an EXTERNAL mailing list!
|Info: send 'help' to java-interest-request@java.sun.com
|
------------------------------
From: arnold@cocolat.East.Sun.COM (Ken Arnold - Sun Labs)
Date: Fri, 22 Sep 1995 16:04:34 -0400
Subject: Re: throws declataration in Java/beta
>From: Christopher Lindblad <cjl@Eng.Sun.COM>:
> From: arnold@cocolat.East.Sun.COM (Ken Arnold - Sun Labs)
>
> A method cannot throw an exception type not declared in its throws
> clause. This is good. You now know which exceptions can be thrown by
> a method.
>
>Then shouldn't any method that uses the "new" operator be required to either
>catch java.lang.OutOfMemoryError or declare it in its throws clause?...
>
>Also, shouldn't any method that uses arrays or accesses an instance variable
>or method on another object either catch java.lang.NullPointerException or
>declare it in its throws clause?...
>
>Perhaps these should be considered "universal" exceptions, in that one should
>assume that all methods throw them. In that case, shouldn't
>InterruptedException be counted as a "universal" exception too?
You are absolutely correct. In fact, Java has such "universal"
exceptions, such as NullPointerException and OutOfMemoryError. And you
don't have to declare them, since they can happen anytime to any code.
These are all extensions of the RuntimeException class, which do not
have to be declared in signatures.
And, no, InterruptedException is not and should not be one of them,
since it is only of interest to the thread involved. Otherewise
InterruptedException would cause thread death, since an unhandled
exception in run() will result in run() terminating, which stops the
thread. This is probably not the expected behavior.
Ken Arnold
------------------------------
From: Thomas.Ball@Eng.Sun.COM (Thomas Ball)
Date: Tue, 26 Sep 1995 16:31:54 -0700
Subject: Resend: Re: Debugging Java
The "use" command (like in dbx) shows the list of directories which
will be searched to find a source file. By default, it uses your
classpath -- that's a poor choice for source files, but it's the only
clue I have (it's been said that Californian==clueless, but that's off
the subject). If you specify a colon-deliminated list of source
directory roots with the "use" command, jdb should have no trouble
looking up source files. Here's part of the path I use:
main[1] use .:/home/tball/java/src/share/java
Note that you only need the top of the source tree if it matches the
class hierarchy, that is, if the package name can be used as part of the
path. For example, jdb would lookup java.lang.String by taking each
path, appending the package, and then adding the source file name
(stored in the class file), so it would try (using the above path):
./java/lang/String.java (not there...)
/home/tball/java/src/share/java/java/lang/String.java (a winner!)
Note: if you are doing remote debugging, specify the source file paths
used on the remote machine. The source files are actually copied down,
so you have some assurance that those are the actual source files.
I'll be adding a way to store the initial jdb setup commands, so you
won't need to always enter them anymore.
Your second problem points to missing features (though soon to be
added). Although you can set breakpoints either by line number or
method name, you can currently only clear them by line number. To make
things more painful, there's no way today to list the current
breakpoints.
The good news is that when you hit a breakpoint in a class which has
line number information (the default), the source file and the line
number of the breakpoint will be displayed in the breakpoint event
message. Here's an example:
running ...
main[1] stop in TicTacToe.mouseUp
Breakpoint set in TicTacToe.mouseUp
Breakpoint hit: TicTacToe.mouseUp (TicTacToe.java:235)
AWT-Motif[1] clear TicTacToe.mouseUp
"TicTacToe.mouseUp" is not a valid id or class name. <== to be fixed
AWT-Motif[1] clear TicTacToe:235
Breakpoint cleared at TicTacToe: 235
AWT-Motif[1] cont
Fixed in the next release, as they say.
Tom
> Hi Thomas ,
>
> I decided to try out some of the java debugging commands using TicTacTac .
> Everytime I do a list to try and see the source code I get a message saying
> "Unable to find $JAVAHOME/demo/TicTacToe/TicTacToe.java" . I am also having
> problems with clearing breakpoints .
> Maybe I'm doing something wrong . Please can you clarify the usage of these 2
> commands . Your help will be most appreciated .
>
> Many Thanks ,
>
> Mushtaq
------------------------------
From: James C Deikun <jcdst10+@pitt.edu>
Date: Tue, 26 Sep 1995 20:44:24 -0400 (EDT)
Subject: Re: Setting Boundaries (was Re: JDK Question)
On Fri, 22 Sep 1995, Chuck McManis wrote:
>
> Actually, adding more java files doesn't impact portability since they
> just work. There are currently 28 classes in the java.* hierarchy that
> have native methods (and thus require porting). Pure java code works the
> same where ever it runs.
I wonder how many of those native method classes are in java.awt.*.
In any case, a third-party implementation still has to duplicate the
library code unless it wants to work only in conjunction with the Sun
distribution, so the libraries still add work that could have an especial
impact on producers with low budgets.
- --
James "impacted?!" Deikun
------------------------------
From: cmcmanis@scndprsn.Eng.Sun.COM (Chuck McManis)
Date: Tue, 26 Sep 1995 17:49:41 -0700
Subject: Re: regular expressions in Java
>Several people have pointed out how valuable unicode-savvy regular
>expressions would be to Java, but the Java team never responds to this
>question. I wish they would.
Ok, I'm on the Java team, I don't have a *CLUE* how one could express
a regular expression that would cull Thai and Korean strings from
a generic set of unicode strings.
>Or maybe the answer is, "Not now, not ever, and this is why...." There
>could be a lot of very good reasons. You haven't hesitated to share your
>reasons for not including various other language features.
I think the folks should take silence to mean "Gee, that's an idea amongst
the eight bazillion that we can't just pop off an answer to." It neither
endorses nor condemns the idea. I can also say that it would be MUCH
more productive to have the dialog start with "These are my ideas for
a regular expression syntax to deal with unicode." UNICODE hacking is
an art that, when jumped into lightly, bites one in the more sensistive
parts.
We would LOVE to have an RE languge for UNICODE, but its down somewhere
below the Mac port I believe in priority. (No, I can't tell you when you
can get the Mac port either :-()
- --Chuck
------------------------------
From: MikeDacon@aol.com
Date: Tue, 26 Sep 1995 23:24:01 -0400
Subject: Java Progress and the Java team
Chuck McManis writes:
>>>
I think the folks should take silence to mean "Gee, that's an idea amongst
the eight bazillion that we can't just pop off an answer to." It neither
endorses nor condemns the idea. I can also say that it would be MUCH
more productive to have the dialog start with "These are my ideas for
a regular expression syntax to deal with unicode." UNICODE hacking is
an art that, when jumped into lightly, bites one in the more sensistive
parts.
We would LOVE to have an RE languge for UNICODE, but its down somewhere
below the Mac port I believe in priority. (No, I can't tell you when you
can get the Mac port either :-()
<<<
I'd just like to thank Chuck and the Java team for responding to posts on
this list. I've have seen alot of posts from them lately and appreciate it.
I'd also like to recommend that we all give the Java team a little slack. We
all know that Java has the potential to be something really special. They
know it too and are trying to pull it off. Constructive criticism and
assistance is much more in need now then feature bashing.
When I was in the Army, a golden rule for briefing the commander was that you
never present a problem without giving him three solutions. If we could
follow that, Java development could precede faster.
- Mike Daconta
Mystech Associates, Inc.
------------------------------
From: "John D. Mitchell" <johnm@mitchell.org>
Date: Tue, 26 Sep 1995 20:44:40 -0700
Subject: Java Grammar
Proposed Standard
Java Programming Language
Grammar Specification
September 26, 1994
AUTHORS:
Terence J. Parr parrt@parr-research.com
John D. Mitchell johnm@mitchell.org
Gary Funck gary@intrepid.com
OWNERSHIP:
For the moment, we maintain the copyright on this grammar.
REVISION:
1.00 Initial proposal
LOCATION:
This file is located at:
ftp://ftp.parr-research.com/pub/Java/java.g.proposed
NOTES:
This grammar is designed for language specification purposes and is
*not* executable. Its purpose is to define the syntactic structure of
the Java language. Neither PCCTS nor YACC will accept this file as
input. It is most certainly non-LL(k) for any k and probably not
LALR(1) due to context-sensitivity (must use symbol table info to
parse, but due to forward references, one doesn't have that
information). The grammar is much tighter than you'd probably use in
practice; for example, we differentiate between lvalues and rvalues
rather than letting it slide to the semantic analysis phase.
No semantic information is used in this grammar; i.e., we have not
predicated any productions on symbol table information.
It is built from our experience in writing an initial Java front end
using PCCTS. The front end is not yet available. Stay tuned for more
information.
We hope this will facilitate the open discussion of and eventual
standardization of the Java programming language so that we can
all move forward from a safe and sane base and write lots of
truly cool software.
....
------------------------------
From: garya@village.org (Gary Aitken)
Date: Tue, 26 Sep 1995 22:09:47 -0700
Subject: Re: throws declataration in Java/beta
>It is very important to realize that a Java class is a guaranteed interface.
>If an method is declared to throw a certain set of exceptions than there is no
>way a sub class can change that. At first this may seem restrictive, but after
>a while you will realize that it is wonderful to have this guarantee.
It's not clear to me what's so wonderful about this guarantee.
There is no similar guarantee that a subclass will not compromise the intended
behavior of its base in numerous other ways. What makes exceptions special?
Gary Aitken garya@village.org
------------------------------
From: Arthur.Vanhoff@Eng.Sun.COM (Arthur van Hoff)
Date: Tue, 26 Sep 1995 21:27:49 -0800 (PDT)
Subject: Re: throws declataration in Java/beta
Hi Gary,
> >It is very important to realize that a Java class is a guaranteed interface.
> >If an method is declared to throw a certain set of exceptions than there is no
> >way a sub class can change that. At first this may seem restrictive, but after
> >a while you will realize that it is wonderful to have this guarantee.
>
> It's not clear to me what's so wonderful about this guarantee.
> There is no similar guarantee that a subclass will not compromise the intended
> behavior of its base in numerous other ways. What makes exceptions special?
Exceptions affect the control flow of the caller. While implementing
this feature we found a number of bugs in HotJava were we simply didn't
realize that a certain exception could thrown.
Have fun,
Arthur van Hoff (avh@eng.sun.com)
http://java.sun.com/people/avh/
Sun Microsystems Inc, M/S UPAL02-301,
100 Hamilton Avenue, Palo Alto CA 94301, USA
Tel: +1 415 473 7242, Fax: +1 415 473 7104
------------------------------
From: Simon Spero <ses@tipper.oit.unc.edu>
Date: Tue, 26 Sep 1995 21:50:47 -0700 (PDT)
Subject: Re: Sending an object across the net...
On Fri, 22 Sep 1995, Derek Hamner wrote:
> I have written simple client & server based on the sun.net classes and I
> would like to know if it would be possible to extend the
> DataInput/OutputStream classes to accommodate more complex types. I
> would like to be able to send any simple object across the network, and
> then reconstruct it on the other side. Is this possible?
>
> Any help or pointers to past discussions on this topic would be greatly
> appreciated.
>
Not using datainput/output, but... I'm currently working on a compiler
for a subset of ASN.1 generating encoders for the PER and BER. This will
generate objects that can encode and decode themselves, as opposed to
taking arbitrary objects and serialising them (java's reflective
operators are too weak to do this)
Simon
------------------------------
From: Nathan Loofbourrow <loofbour@cis.ohio-state.edu>
Date: Wed, 27 Sep 1995 01:16:29 -0400
Subject: Java VM clarifications
Thanks to all for their help in parsing the Java class file format,
esp. C. McManis for his Java-based parser.
I'm seeing a few opcodes for which the alpha3 Java VM docs aren't
adequate. To wit:
1. Opcodes 135 and 255 appear in compiled code (such as the Java
contest winners :-), but isn't mentioned anywhere in the VM spec,
from what I can tell.
2. Opcode 132 is mentioned twice in the spec, once as the i2l type
conversion instruction and once as the iinc increment
instruction. I imagine this relates to #1 above.
Any pointers/corrections?
nathan
------------------------------
From: Sami.Shaio@Eng.Sun.COM (Sami Shaio)
Date: Tue, 26 Sep 1995 22:42:37 -0700
Subject: Re: GUI design
Using absolute positioning is not a good idea since different native
implementations will have different sizes for things. You should use
layout objects since they will behave properly when the size of
the widgets varies.
- --sami
------------------------------
End of java-interest-digest V1 #191
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