[ The Java FAQ Daily Tips, weekly publication ]
Foreword: Excuse me for
possible mistakes. English is not native language for me.
In this issue:
Hello dear friends!
Question: What are additional types of GC do exist in the J2SE
platform, version 1.4.2?
1. The throughput collector: this collector uses a parallel version of the young
generation collector. It is used if the -XX:+UseParallelGC option is passed on
the command line. The tenured generation collector is the same as the default
2. The concurrent low
pause collector: this collector is used if the -XX:+UseConcMarkSweepGC is passed
on the command line. The concurrent collector is used to collect the tenured
generation and does most of the collection concurrently with the execution of
the application. The application is paused for short periods during the
collection. A parallel version of the young generation copying collector is used
with the concurrent collector if the combination -XX:+UseConcMarkSweepGC
-XX:+UseParNewGC is passed on the command line.
This kind is also known as concurrent GC.
3. The incremental
(sometimes called train) low pause collector: this collector is used only if
-Xincgc is passed on the command line. By careful bookkeeping, the incremental
garbage collector collects just a portion of the tenured generation at each
minor collection, trying to spread the large pause of a major collection over
many minor collections. However, it is even slower than the default tenured
generation collector when considering overall throughput.
-XX:+UseParallelGC should not be used with -XX:+UseConcMarkSweepGC. The argument
parsing in the J2SE platform, version 1.4.2 should only allow legal combinations
of command line options for garbage collectors, but earlier releases may not
detect all illegal combinations and the results for illegal combinations are
Also important to
remember: always try default GC before using additional GCs!
pop-up ads driving you crazy???
Your computer may be infected with a parasite!
Click here to scan your computer now
Question: With 1.3.1 we got 4GB heaps on Solaris, why can't I get
this to work on Windows?
Answer: It's due to fragmentation of the address space. After Windows
has loaded all its stuff, plus the java dlls, the largest available continuous
chunk of addresses for the heap is about 1.4-1.6G on Win/NT. Might be smaller on
If you really need more
space they can try rebasing java.exe and the JDK dlls higher. But that won't buy
you much (maybe a couple hundred meg).
from the Java Hotspot Virtual Machine FAQ:
Latest posts on our message
Compositing(image and movie) in Java
I would like to
do some compositing in Java. Currently I'm using QuickTime for Java
to do it. It is very easy. However I always get some runtime
exception when I execute the program. So I want to switch to pure
Java. I want to play a movie as the background, probably using JMF.
Then do some animation with some images and text in front of the
movie. Is this possible? Any advice or sample program?
please help here
JTabbedPane and focus issue
Maybe I'm just
doing things a bit different than anyone else and I'm wrong. Here's
the deal: I have a focus traversal policy for each frame in my app.
When I used a personally-created subclass of JTabbedPane it was
trying to set focus on a component on a non-visible tab. So I fixed
that problem by not allowing focus to go to non-visible tab panels.
Now I want, on a tab change, to set focus on the first focusable
component of the new tab. But at the time I get a change event to
hook this call the old tab is still visible and the second one
So my first fix...
thread continues here
How to realize my project
I’m new on java and i should do a project to create an application
to design Workflow on thin client (IE6) or a software and use Java
Web Start. The design is base on the state-chart diagram. All the
information concerning items (position, size) will be store under
lotus Notes Documents.
Each item (state, chart relations) will have different values
selected from list. Each list will be fill in with informations
descended from data contains under Lotus Notes documents.
thread continues here
39 comments | | Java Newsletters | Score: 5