How to simplify a null-safe compareTo() implementation?

Question

I\'m implementing compareTo() method for a simple class such as this (to be able to use Collections.sort() and other goodies offered by the Java pl

Answer 1

This is my implementation that I use to sort my ArrayList. the null classes are sorted to the last.

for my case, EntityPhone extends EntityAbstract and my container is List < EntityAbstract>.

the "compareIfNull()" method is used for null safe sorting. The other methods are for completeness, showing how compareIfNull can be used.

@Nullable
private static Integer compareIfNull(EntityPhone ep1, EntityPhone ep2) {

    if (ep1 == null || ep2 == null) {
        if (ep1 == ep2) {
            return 0;
        }
        return ep1 == null ? -1 : 1;
    }
    return null;
}

private static final Comparator AbsComparatorByName = = new Comparator() {
    @Override
    public int compare(EntityAbstract ea1, EntityAbstract ea2) {

    //sort type Phone first.
    EntityPhone ep1 = getEntityPhone(ea1);
    EntityPhone ep2 = getEntityPhone(ea2);

    //null compare
    Integer x = compareIfNull(ep1, ep2);
    if (x != null) return x;

    String name1 = ep1.getName().toUpperCase();
    String name2 = ep2.getName().toUpperCase();

    return name1.compareTo(name2);
}
}


private static EntityPhone getEntityPhone(EntityAbstract ea) { 
    return (ea != null && ea.getClass() == EntityPhone.class) ?
            (EntityPhone) ea : null;
}