Example Depot

// Create the sets Set set1 = new HashSet(); Set set2 = new HashSet(); // Add elements to the sets ... // Copy all the elements from set2 to set1 (set1 += set2) // set1 becomes the union of set1 and set2 set1.addAll(set2); // Remove all the elements in set1 from set2 (set1 -= set2) // set1 becomes the asymmetric difference of set1 and set2 set1.removeAll(set2); // Get the intersection of set1 and set2 // set1 becomes the intersection of set1 and set2 set1.retainAll(set2); // Remove all elements from a set set1.clear();