Union or intersection of Java Sets
The simplest one-line solution is this: set1.addAll(set2); // Union set1.retainAll(set2); // Intersection The above solution is destructive, meaning that contents of the original set1 my change. If you don’t want to touch your existing sets, create a new set: var result = new HashSet<>(set1); // In Java 10 and above Set<Integer> result = new HashSet<>(set1); … Read more