How to compare equality of lists of arrays with modern Java?

Question

I have two lists of arrays.

How do I easily compare equality of these with Java 8 and its features, without using external libraries? I am looking for a \"bett

Answer 1

You could use a stream if the lists are random access lists (so that a call to get is fast - generally constant time) leading to:

//checks for null and size before
boolean same = IntStream.range(0, list1.size()).allMatch(i -> Arrays.equals(list1.get(i), list2.get(i)));

However, you might give as parameters some implementations that are not (such as LinkedLists). In this case, the best way is to use the iterator explicitly. Something like:

boolean compare(List list1, List list2) {

    //checks for null and size

    Iterator iteList1 = list1.iterator();
    Iterator iteList2 = list2.iterator();

    while(iteList1.hasNext()) {
        if(!Arrays.equals(iteList1.next(), iteList2.next())) {
            return false;
        }
    }
    return true;
}