Remove common number from two arrays

• Need to remove common number 4 from both arrays
• Input
• int[] arr1 = { 1, 4, 6, 7, 8 };
• int[] arr2 = { 2, 4, 5, 9, 0 };
• Output
• int[] arr1 = { 1, 6, 7, 8 };
• int[] arr2 = { 2, 5, 9, 0 };

• RemoveCommonElements.java
• public class RemoveCommonElements { public static void main(String[] args) { RemoveCommonElements app = new RemoveCommonElements(); app.commonRemove(); } private void commonRemove() { int[] arr1 = { 1, 4, 6, 7, 8 }; int[] arr2 = { 2, 4, 5, 9, 0 }; for (int e : arr1) { if (contains(arr2, e)) { remove(arr1, e); remove(arr2, e); } } System.out.print(arr1); System.out.print(arr2); } private boolean contains(int[] arr, int e) { for (int i : arr) { if (i == e) { return true; } } return false; } private int[] remove(int[] arr, int e) { for (int i = 0; i < arr.length; i++) { if (arr[i] == e) { for (int j = i; j < arr.length-1; j++) { arr[j] = arr[j + 1]; } } } return arr; } } ######### RESULT ########## 1, 6, 7, 8, 8 2, 5, 9, 0 ,0
• In below example CopyOnWriteArrayList will be concurrent in type and ConcurrentModificationException can be prevent
• /** * Get UNION list * Get INTERSECTION LIST by retainAll //common elements * Remove intersection from union */ private static void removeCommonElements() { List list1 = Arrays.asList(1, 2, 3, 4, 5, 6); List list2 = Arrays.asList(10, 2, 3, 40, 50, 60); List union = new ArrayList(list1); union.addAll(list2); List intersection = new ArrayList<>(list1); // only common elements intersection.retainAll(list2); union.removeAll(intersection); System.out.println(union); }