Google Guava “zip” two lists

Question

Using Google Guava (Google Commons), is there a way to merge two equally sized lists into one list, with the new list containing composite objects of the two input lists?

Answer 1

Here's a generic way to zip lists with vanilla Java. Lacking tuples, I opted to use a list of map entries (If you don't like to use map entries, introduce an additional class ZipEntry or something).

public static  List> zip(List zipLeft, List zipRight) {
    List> zipped = new ArrayList<>();
    for (int i = 0; i < zipLeft.size(); i++) {
        zipped.add(new AbstractMap.SimpleEntry<>(zipLeft.get(i), zipRight.get(i)));
    }
    return zipped;
}

To support arrays as well:

@SuppressWarnings("unchecked")
public static  Map.Entry[] zip(T1[] zipLeft, T2[] zipRight) {
    return zip(asList(zipLeft), asList(zipRight)).toArray(new Map.Entry[] {});
}

To make it more robust add precondition checks on list sizes etc, or introduce left join / right join semantics similar to SQL queries.