BAEL-6839-get-random-from-set (#14606)

* BAEL-6839-get-random-from-set

* edge cases

core-java-modules/core-java-lang-6/src/main/java/com/baeldung/randominset/RandomInSetUtil.java

@@ -0,0 +1,50 @@
+package com.baeldung.randominset;
+
+import java.util.HashSet;
+import java.util.Random;
+import java.util.Set;
+import java.util.concurrent.ThreadLocalRandom;
+
+public class RandomInSetUtil {
+
+    public static <T> T getByRandomClass(Set<T> set) {
+        if (set == null || set.isEmpty()) {
+            throw new IllegalArgumentException("The Set cannot be empty.");
+        }
+        int randomIndex = new Random().nextInt(set.size());
+        int i = 0;
+        for (T element : set) {
+            if (i == randomIndex) {
+                return element;
+            }
+            i++;
+        }
+        throw new IllegalStateException("Something went wrong while picking a random element.");
+    }
+
+    public static <T> T getByThreadLocalRandom(Set<T> set) {
+        if (set == null || set.isEmpty()) {
+            throw new IllegalArgumentException("The Set cannot be empty.");
+        }
+        int randomIndex = ThreadLocalRandom.current().nextInt(set.size());
+        int i = 0;
+        for (T element : set) {
+            if (i == randomIndex) {
+                return element;
+            }
+            i++;
+        }
+        throw new IllegalStateException("Something went wrong while picking a random element.");
+    }
+
+    public static void main(String[] args) {
+        Set<String> animals = new HashSet<>();
+        animals.add("Lion");
+        animals.add("Elephant");
+        animals.add("Giraffe");
+
+        String randomAnimal = getByThreadLocalRandom(animals);
+        System.out.println("Randomly picked animal: " + randomAnimal);
+    }
+
+}