问使用多个键对Java对象进行排序

EN

class Duck {
    DuckAge age; //implements Comparable
    DuckWeight weight; //implements Comparable
    String name;
}
List<Duck> ducks = Pond.getDucks();

Collections.sort(ducks, new Comparator<Duck>(){
    @Override
    public int compare(Duck d1, Duck d2){
        int weightCmp = d1.weight.compareTo(d2.weight);
        if (weightCmp != 0) {
            return weightCmp;
        }
        int ageCmp = d1.age.compareTo(d2.age);
        if (ageCmp != 0) {
            return ageCmp;
        }
        return d1.name.compareTo(d2.name);
    }
});