Question

Which class would work best for a non-ordered list of pairs? I’ll be taking a bunch of (float,short) pairs and will need to be able to perform simple math (like multiplying the pair together to return a single float, etc). List only takes one argument, and HashMap won’t allow duplicates (as far as I know). Any thoughts?

Answer 1

You can use the Entry<U,V> class that HashMap uses but you’ll be stuck with its semantics of getKey and getValue:

List<Entry<Float,Short>> pairList = //...

My preference would be to create your own simple Pair class:

public class Pair<L,R> {
    private L l;
    private R r;
    public Pair(L l, R r){
        this.l = l;
        this.r = r;
    }
    public L getL(){ return l; }
    public R getR(){ return r; }
    public void setL(L l){ this.l = l; }
    public void setR(R r){ this.r = r; }
}

Then of course make a List using this new class, e.g.:

List<Pair<Float,Short>> pairList = new ArrayList<Pair<Float,Short>>();

You can also always make a Lists of Lists, but it becomes difficult to enforce sizing (that you have only pairs) and you would be required, as with arrays, to have consistent typing.