I have this list: and I want to get 4 random letters from it, but including repetition. Running this will only give me 4 unique letters, but never any repeating letters: How do I get a list of 4 colors, with repeating letters possible?
Compute the discrete cumulative density function (CDF) of your list — or in simple terms the array of cumulative sums of the weights. Then generate a random number in the range between 0 and the sum of all weights (might be 1 in your case), do a binary search to find this random number in … Read more
Here you can use my method for generating Random String The above method from my bag using to generate a salt string for login purpose.
There’s a very interesting discussion of this type of issue here: http://www.titov.net/2005/09/21/do-not-use-order-by-rand-or-how-to-get-random-rows-from-table/ I think with absolutely no assumptions about the table that your O(n lg n) solution is the best. Though actually with a good optimizer or a slightly different technique the query you list may be a bit better, O(m*n) where m is the number … Read more
Using Collections to shuffle an array of primitive types is a bit of an overkill… It is simple enough to implement the function yourself, using for example the Fisher–Yates shuffle:
You could use e.g. r.nextInt(101) For a more generic “in between two numbers” use: This gives you a random number in between 10 (inclusive) and 100 (exclusive)
That’s because a long is 64 bits and an int is 32 bits, not to mention you’re going from floating-point to integer. To go from long to int, you’re going to have to discard some information, and the compiler can’t/won’t do that automatically. You’re going to have to explicitly say so through a cast: Alternatively, you can use java.util.Random:
To generate a random value between rangeMin and rangeMax: