EN
Java - get random element from set
4 points
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public static String randomStringFromSet() {2
Set<String> set = new HashSet<>(Arrays.asList("A", "B", "C", "D", "E", "F"));3
List<String> list = new ArrayList<>(set);4
5
int size = list.size();6
int randIdx = new Random().nextInt(size);7
8
String randomElem = list.get(randIdx);9
return randomElem;10
}Example:
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System.out.println(randomStringFromSet()); // C2
System.out.println(randomStringFromSet()); // D3
System.out.println(randomStringFromSet()); // BNot very efficient because we need to create ArrayList based on HashSet.
So if the set is not too large it's ok solution.
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public static String randomStringFromSet2() {2
Set<String> set = new HashSet<>(Arrays.asList("A", "B", "C", "D", "E", "F"));3
int size = set.size();4
5
int currIdx = 0;6
int randIdx = new Random().nextInt(size);7
8
for (String letter : set) {9
if (currIdx == randIdx) {10
return letter;11
}12
currIdx++;13
}14
15
return null;16
}Example:
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System.out.println(randomStringFromSet2()); // D2
System.out.println(randomStringFromSet2()); // F3
System.out.println(randomStringFromSet2()); // E- Iterate over the set and generate random number within size of the set.
- Iterate over the elements of the set and keep index
- If index is equal to the randomly generated index then return element from set.