Re: ZoneView or ways of dealing with large objects?

From:

"Oliver Wong" <owong@castortech.com>

Newsgroups:

comp.lang.java.help

Date:

Thu, 29 Jun 2006 14:16:27 GMT

Message-ID:

<%gRog.89328$A8.81419@clgrps12>

"Mark Space" <markspace@sbcglobal.net> wrote in message
news:44A372C3.4040201@sbcglobal.net...

Oliver Wong wrote:

"Mark Space" <markspace@sbcglobal.net> wrote in message
news:FUAng.28746$VE1.18652@newssvr14.news.prodigy.com...

Hi all.

I've got a program which displays potentially very large files. Files
larger than 250k or so cause Java to run out of memory. I'm building a
bigger view based on the file (converting binary to hex) so this view
object just over one megabyte when the JVM poops out.

Is there some standard way of dealing with this? I'm looking at
ZoneView, but there are really no instructions or examples available.
Does anyone have a pointer to one? What about any kind of View, I
haven't been able to locate any of those either.

I'm probably going to implement this manually because I only have one
scrollbar to worry about, but I'd like to extend my knowledge of Java so
any help you can give would be great.

Are you sure this is where the problem lies? I've written Java
programs which load text files in the hundreds of megabytes into memory
without too much trouble (assuming I give Java enough memory, e.g. with
"-vmargs -Xms256m -Xmx512m"). Are you developing on a memory constrained
device?

Well, not 100% sure, but it works for small files, and generates a OOM
error for large ones. I'm working on a PC, under Netbeans 5.x, and it's
not particularily memory constrained. I only have 256Mb of memory, but I
don't think that's holding the JVM back.

By memory-constrained device, I meant like embedded processors with 256Kb of
RAM.

I'm also doing a LOT of string manipulation. I'm building a JTextArea
object basically one and two characters at a time. So the heap is likely
about as full of garbage as it is likely to get.

Are you using the StringBuilder or StringBuffer classes for your string
manipulations?

I thought about asking the JVM to increase it's memory size, but that
didn't seem like a scalable solution. Plus I might have to ask users to
do the same. So I'm looking for something scalable, something that'll
work even when I point it at a 10 Gb file.

Have you considered memory-mapped files?

- Oliver