Home/ Questions/Q 69631
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-10T19:36:15+00:00

I have been working on a childish little program: there are a bunch of

  • 0

I have been working on a childish little program: there are a bunch of little circles on the screen, of different colors and sizes. When a larger circle encounters a smaller circle it eats the smaller circle, and when a circle has eaten enough other circles it reproduces. It’s kind of neat!

However, the way I have it implemented, the process of detecting nearby circles and checking them for edibility is done with a for loop that cycles through the entire living population of circles… which takes longer and longer as the population tends to spike into the 3000 before it starts to drop. The process doesn’t slow my computer down, I can go off and play Dawn of War or whatever and there isn’t any slow down: it’s just the process of checking every circle to see if it has collided with every other circle…

So what occurred to me, is that I could try to separate the application window into four quadrants, and have the circles in the quadrants do their checks simultaneously, since they would have almost no chance of interfering with each other: or something to that effect!

My question, then, is: how does one make for loops that run side by side? In Java, say.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Computers are usually single tasked, this means they can usually execute one instruction at a time per CPU or core.

    However, as you have noticed, your operation system (and other programs) appear to run many tasks at the same time.

    This is accomplished by splitting the work into processes, and each process can further implement concurrency by spawning threads. The operation system then switches between each process and thread very quickly to give the illusion of multitasking.

    In your situation,your java program is a single process, and you would need to create 4 threads each running their own loop. It can get tricky, because threads need to synchronize their access to local variables, to prevent one thread editing a variable while another thread is trying to access it.

    Because threading is a complex subject it would take far more explaining than I can do here.

    However, you can read Suns excellent tutorial on Concurrency, which covers everything you need to know:

    http://java.sun.com/docs/books/tutorial/essential/concurrency/

    • 0