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

The for loop at least can be streamified, leading to:

return (list1.size()==list2.size() &&        IntStream.range(0, list1.size())                 .allMatch(i -> Arrays.equals(list1.get(i), list2.get(i)));

using zip (which originates from lambda b93) function from https://stackoverflow.com/a/23529010/755183, code could look like:

boolean match = a.size() == b.size() &&                 zip(a.stream(), b.stream(), Arrays::deepEquals).                allMatch(equal -> equal)

update

in order to check size of arrays first and then content this could be a solution to consider

final boolean match = a.size() == b.size()                    && zip(a.stream(), b.stream(), (as, bs) -> as.length == bs.length).                      allMatch(equal -> equal)                   && zip(a.stream(), b.stream(), Arrays::deepEquals).                      allMatch(equal -> equal);

1) Solution based on Java 8 streams:

List<List<String>> first = list1.stream().map(Arrays::asList).collect(toList());List<List<String>> second = list2.stream().map(Arrays::asList).collect(toList());return first.equals(second);

2) Much simpler solution (works in Java 5+):

return Arrays.deepEquals(list1.toArray(), list2.toArray());

3) Regarding your new requirement (to check the contained String arrays length first), you could write a generic helper method that does equality check for transformed lists:

<T, U> boolean equal(List<T> list1, List<T> list2, Function<T, U> mapper) {    List<U> first = list1.stream().map(mapper).collect(toList());    List<U> second = list2.stream().map(mapper).collect(toList());    return first.equals(second);}

Then the solution could be:

return equal(list1, list2, s -> s.length)    && equal(list1, list2, Arrays::asList);