I need to generate a random integer for a process that I'm working on. I know I could use Math.Random() to do this, however here is where I'm stuck. I've got a list of Integers...they aren't necessarily in any order or within any range of numbers. Basically I need to re-order the list so it is completely random. I'm not sure how to go about doing this...it needs to be very efficient. The only thing I've thought of so far is getting a random number from Math.Random, checking to see if it is in my list, if it is remove it from my list and add it to a new list...and repeat until my old list is empty...it seems like i will potentially generate a lot of extra random numbers that will not be in my list. Any ideas of an efficient way to put a list into a random order?

One thing I have considered is putting each value into a HashMap and looping through the HashMap key by key....but I'm not sure how random that would be since I'd be putting them into the HashMap sequentially and pulling them out sequentially...


This post has been edited by fahlyn: 7 Feb, 2008 - 12:05 PM

yeah , thats an excessive way to do it.

you could just build an array of the numbers you have,

and then randomly pick which spot in the array to use.

so if your array has numbers :

5, 13, 29, 55

then your math random picks an int < 4.

and it will randomly pick one of those

Yeah, I'm a dork. I literally had that same thought 30 seconds after I posted this. Here's what I'm doing, and it seems to work fine. Sorry to waist your time, thanks.