Is it possible in java make something like Comparator but for implementing custom equals() and hashCode()

Question

I have an array of objects and I want to concatenate it with another array of objects, except that objects that have same id\'s. That objects are used in many places in the

Answer 1

Just had this problem and worked up a simple solution. Not sure how memory-intensive it is; I'm sure people can refine it down the line.

When the Comparator returns 0, the elements match.

public static  Set filterSet(Set set, Comparator comparator){
    Set output = new HashSet();
    for(E eIn : set){
        boolean add = true;
        for(E eOut : output){
            if(comparator.compare(eIn, eOut) == 0){
                add = false;
                break;
            }
        }
        if(add) output.add(eIn);
    }
    return output;
}

My use case was that I needed to filter out duplicate URLs, as in URLs that point to the same document. The URL object has a samePage() method that will return true if everything except the fragment are the same.

filtered = Misc.filterSet(filtered, (a, b) -> a.sameFile(b) ? 0 : 1);