Marinol posted:

I'm working with probabilities and designing a network simulator that drops packets with probability p. I've never dealt with probabilities before in Java, and google wasn't of much help, so this is why I ask in this thread: How do I make sure stuff happens with probability p? I was thinking of having a double p, and using Math.random(), but I don't know exactly how to use these two things to come up with the answer.

Any help would be appreciated! Sorry if this is a really stupid question.

Paolomania posted:

If you take a look at java.util.Arrays, this is exactly the kind of functionality that this class's static methods handle. The lack of shuffling functionality for primitives could be considered a hole in this class's functionality.

zootm posted:

There's no Arrays.shuffle for primitive arrays which seems like a particularly annoying omission; no idea what's going on there.

KuruMonkey posted:

So; the array of chars is a subclass of Object, but the chars in it aren't. And the function definition I was reading was actually wanting a collection of Object subclasses, not primitives.

Paolomania posted:

So it looks like draw performance. A few things to try:

- look into whether or not the shared memory extension is turned on. If not, your application is doing extra buffer copies to the X server.

- use GraphicsConfiguration.getImageBufferCapabilities() to see if you have access to all the hardware acceleration that you think you do. Try turning off transparency to see if that one rendering option is the culprit.

- perhaps that image processing you are doing to create the alpha values is causing the JVM to treat your images as unaccelerated buffers that need to be kept both in the heap as well as in video RAM. You could maybe try some tricks to try to force the JVM to store your images in video RAM (see here).

Elos posted:

I'm already using GraphicsConfiguration.createCompatibleImage for my images and I just tried emoving anything transparceny or alpha compositing related but still getting horrible performance. How can I find out wether shared memory extension is turned on?

getImageCapabilities().isAccelerated() returns false which I presume is a bad sing.

Elos posted:

That method just loops trough an array asking the tiles to draw themselves. I don't have any real reason for drawing it constantly besides wanting to see how it's done and hell, I might want to make it a pseudo-realtime like Diablo or something.

I'm doing all the transparency and color mask stuff before the gameloop so it just draws simple 16x16 images on the screen and checks for key events. There must be something strange going on in the linux JRE.

EDIT: Is there an easy way to find out which method is hogging all the CPU?

Elos posted:

getImageCapabilities().isAccelerated() returns false which I presume is a bad sing.

magicalblender posted:

Is it possible to make a decorator class that doesn't call super() on its superclass?

TRex EaterofCars posted:

In order to answer your general question, what kind of monitoring do you need to perform?

magicalblender posted:

Widget is actually a PacketHandler class, and the methods I'm interested in are actually

code:

void receive(PacketTypeA p);
void receive(PacketTypeB p);
void receive(PacketTypeC p);
//etc. 

One kind of packet handles chat messages, and I want to record those messages in a log file. So essentially, I wanted to do this;

code:

public class NoisyPacketHandler{
 void receive(PacketTypeC p){
  log("message from user " + p.sender + ": " + p.message);
  parent.receive(p);
 }
}

chippy posted:

That should do it. Set up a user account via whatever you're using to admin your database, use the login details for that for userName and password and the url will be, as you said, jdbc:mysql://yourdomainhere.com. You'll need to install the MySQL Connector (http://www.mysql.com/products/connector/) and install it/add it to your build path as well. If you're using Eclipse you can do it from within that. What's happening when you try to run it?

Internet Janitor posted:

Jo: Spiffy. Is that lighting baked into your maps, or calculated on the fly? I think your perspective is slightly off. If those walls are one square high, this shadow line should be moved down, so the shadow begins where the back of that wall would touch the ground:

Aleksei Vasiliev posted:

Got a problem.
I'm trying to grab the videocard name (in Windows) by executing dxdiag then reading the log file.

But:

code:

File report = File.createTempFile("dxdiag", ".txt");
ProcessBuilder procbuild = new ProcessBuilder("dxdiag", "/t", report.toString());
Process proc = procbuild.start();
proc.waitFor()

^{pastebin of incomplete code}
The process returns 0 immediately because dxdiag spawns a new process to do all its processing, which takes a few seconds. How do I reliably wait until the log file is written before trying to read it? (Is it possible?)

Paolomania posted:

Since the additional process fork leaves you with no connection to the process that actually does the work there is no way to get a notification of its exit from within Java. You would have to just wait a reasonable amount of time or poll the file status (which also involves waiting). Since you know that this is Windows-specific I would wrap the call to dxdiag in a shell script and run (and wait on) the script from Java instead.

TRex EaterofCars posted:

You can spin. Basically a thread with a sleep() in it and a timeout in case the file never gets produced.

Aleksei Vasiliev posted:

Okay, what's different between cmd and a batch file? Running dxdiag from cmd returns immediately, just like Java, but a batch file waits for it to finish. why are batch files magic
What happens if it wakes up while the file is being written (since it now exists) and starts reading?

Aleksei Vasiliev posted:

Okay, what's different between cmd and a batch file? Running dxdiag from cmd returns immediately, just like Java, but a batch file waits for it to finish. why are batch files magic

Paolomania posted:

http://blogs.msdn.com/b/powershell/archive/2007/01/16/managing-processes-in-powershell.aspx

My guess is it has something to do with automatic piping.

quote:

But what if I do want to wait for the Win32 process? In cmd.exe, you'd do this with "start /wait" but this command is not (directly) available in PowerShell. So what do we do?

Paolomania posted:

Yeah, if what you are trying to do is so windows-graphics-specific, why are you trying to do it in a Java app?

Revitalized posted:

So I'm reviewing my notes for my midterm tomorrow, and I noticed I'm missing something.

What are the pros and cons of Singly Linked Lists and Doubly Linked Lists?

As far as Arrays and LinkedLists go, I know there's a difference in memory space usage, but as far as Singly and Doubly linked list, I'm not sure what's the drawback on a doubly as opposed to a singly. Is there one?

baquerd posted:

Does anyone have any idea what the hell?

Keyboard Kid posted: