Picking a random element from a set

java algorithm language-agnostic random set
Clue Less picture Clue Less · Sep 24, 2008 · Viewed 203.8k times · Source

How do I pick a random element from a set? I'm particularly interested in picking a random element from a HashSet or a LinkedHashSet, in Java. Solutions for other languages are also welcome.

Answer

Khoth picture Khoth · Sep 24, 2008 
int size = myHashSet.size();
int item = new Random().nextInt(size); // In real life, the Random object should be rather more shared than this
int i = 0;
for(Object obj : myhashSet)
{
    if (i == item)
        return obj;
    i++;
}

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