Generate random number from the set {1, 3, 100}

Question

I already know how to generate a random number within a range; but my question is about possibility of generating a number from a set of 2 or more specified numbers. for example: the output must be randomly chosen between exactly "1" or "3" or "100"

Another way to put it is: The value obtained will be any of the three numbers: 1, 3 or 100 (without any of the numbers in between).

How would that work? I don't really see how that's different than 1-100. — hichris123, Dec 14 '13 at 16:47
There is no 'hurry' about it, but I'd noted A) You were new & B) You addressed that thanks to 'everyone' whereas 'no-one' would have been notified of the new comment. ;) — Andrew Thompson, Dec 14 '13 at 17:04
Wow. I've been called a lot of things recently, and 'kind' surely was *not* one of them. ;) — Andrew Thompson, Dec 14 '13 at 17:14

score 6 · Accepted Answer · answered Dec 14 '13 at 16:47

6

Put the numbers in an int[3]
Choose a random number between 0 & 2.
Use that random number as the index of the array.

..is one of many ways.

answered Dec 14 '13 at 16:47

Andrew Thompson

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simple and true; probably the best, tnx – Shervin4030 Dec 14 '13 at 16:58
Best solution if you want the outcomes with equal probabilities. – pjs Dec 14 '13 at 16:58
@pjs you dont mean that salihrkc's solution is not? given that the numbers are divided correctly. – Shervin4030 Dec 14 '13 at 17:03
1

@Shervin4030 salihrkc's solution gives probabilities .33, .33, and .34, i.e., not quite uniformly distributed. Having said that, if you want unequal probabilities then that answer is one way to do it. For instance, change the tests to .25 and .25 if you want to get 100 twice as often as the other two outcomes. – pjs Dec 14 '13 at 17:05
Doh! Make that .25 and .5 if you want to get 100 twice as often and do it correctly. ;) – pjs Dec 15 '13 at 19:12

Zaheer Ahmed · Answer 2 · 2013-12-14T16:54:07.390

1

Random is your solution for it:

public static int generateRandomNumber(int[] availableCollection) {
   Random rand = new Random();
   return availableCollection[rand.nextInt(availableCollection.length)];
}

edited Dec 14 '13 at 16:54

answered Dec 14 '13 at 16:48

Zaheer Ahmed

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score 0 · Answer 3 · answered Dec 14 '13 at 16:48

0

 {1,3,100}

Store them in an array and then select a random element from there. To select random element, see this: http://answers.yahoo.com/question/index?qid=20081025124826AAR8rmY

answered Dec 14 '13 at 16:48

Eisa Adil

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believe me; If I had enough reps; I wouldn't hesitate; sorry – Shervin4030 Dec 14 '13 at 16:58

Salih Erikci · Answer 4 · 2013-12-14T16:54:19.627

0

Java Math.random() generates random numbers between 0.0 and 1.0 you can write a code for what you want. For example:

double random = new Math.random();
random = myRandom(random);

    public double myRandom(double random){

        if(random < 0.33){return 1;}
        else if(random < 0.66) {return 3;}
        else {return 100;}
    }

edited Dec 14 '13 at 16:54

answered Dec 14 '13 at 16:49

Salih Erikci

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Generate random number from the set {1, 3, 100}

4 Answers4