Comparing arrays that have same elements in different order

Question

I wrote below code to compare to arrays that have same elements but in diff order.

 Integer arr1[] = {1,4,6,7,2};
 Integer arr2[] = {1,2,7,4,6};

Answer 1

Do you care about duplicate counts? For example, would you need to distinguish between { 1, 1, 2 } and { 1, 2, 2 }? If not, just use a HashSet:

public static boolean compareArrays(Integer[] arr1, Integer[] arr2) {
    HashSet set1 = new HashSet(Arrays.asList(arr1));
    HashSet set2 = new HashSet(Arrays.asList(arr2));
    return set1.equals(set2);
}

If you do care about duplicates, then either you could use a Multiset from Guava.

If you want to stick with the sorting version, why not use the built-in sorting algorithms instead of writing your own?

EDIT: You don't even need to create a copy, if you're happy modifying the existing arrays. For example:

public static boolean compareArrays(Integer[] arr1, Integer[] arr2) {
    Arrays.sort(arr1);
    Arrays.sort(arr2);
    return Arrays.equals(arr1, arr2);
}

You can also have an optimization for the case where the arrays aren't the same length:

public static boolean compareArrays(Integer[] arr1, Integer[] arr2) {
    // TODO: Null validation...
    if (arr1.length != arr2.length) {
        return false;
    }
    Arrays.sort(arr1);
    Arrays.sort(arr2);
    return Arrays.equals(arr1, arr2);
}