List> - anything more standard than that?

Question

I am making a simple unit tester, where i iterate on pairs of (input, expected) values, and check if a calculated actual value equals the expected.

This is perfectly doable in a simple HashMap<INPUTTYPE, OUTPUTTYPE>, but hash logic is pointless, since i'm going to iterate on all values, and never search in the map, while it would be nice to keep the order of the test cases (pairs of (input, expected)).

A List<Entry<K,V>> seems to work well, but it seems not nice to use an inner component of a Map in a List. It also seems unnatural to create the Pair class to connect input and expected, since Entry is the same thing.

Is there a way using existing java classes in the base libs that support this kind of data very well?

A map is probably *not* what you want; what if there are multiple tests with the same expected value? — Oliver Charlesworth, Dec 04 '14 at 09:15
As far as you want, creating an entry class is easy. I think it is natural to create your own entry class. — javaHunter, Dec 04 '14 at 09:15
You're sort of putting yourself in a no-win situation when you say you don't what to use `Entry` but don't want to create your own because it exists. I think it's pretty natural and easy to make your own if no other option suits your needs. — ChiefTwoPencils, Dec 04 '14 at 09:21

score 1 · Answer 1 · answered Dec 04 '14 at 09:19

A simple Pair would probably be your best choice:

/**
 * @author OldCurmudgeon
 * @param <P>
 * @param <Q>
 */
public class Pair<P extends Comparable<P>, Q extends Comparable<Q>> implements Comparable<Pair<P, Q>> {
  // Exposing p & q directly for simplicity. They are final so this is safe.
  public final P p;
  public final Q q;

  public Pair(P p, Q q) {
    this.p = p;
    this.q = q;
  }

  public P getP() {
    return p;
  }

  public Q getQ() {
    return q;
  }

  @Override
  public String toString() {
    return "<" + (p == null ? "" : p.toString()) + "," + (q == null ? "" : q.toString()) + ">";
  }

  @Override
  public boolean equals(Object o) {
    if (!(o instanceof Pair)) {
      return false;
    }
    Pair it = (Pair) o;
    return p == null ? it.p == null : p.equals(it.p) && q == null ? it.q == null : q.equals(it.q);
  }

  @Override
  public int hashCode() {
    int hash = 7;
    hash = 97 * hash + (this.p != null ? this.p.hashCode() : 0);
    hash = 97 * hash + (this.q != null ? this.q.hashCode() : 0);
    return hash;
  }

  @Override
  public int compareTo(Pair<P, Q> o) {
    int diff = p == null ? (o.p == null ? 0 : -1) : p.compareTo(o.p);
    if (diff == 0) {
      diff = q == null ? (o.q == null ? 0 : -1) : q.compareTo(o.q);
    }
    return diff;
  }

}

score 0 · Answer 2 · answered Dec 04 '14 at 09:16

0

You could use 2 arrays and compare expected[i] with actual[i] if you don't want to create any new class as there isn't a standard Tuple/Pair in core java.

answered Dec 04 '14 at 09:16

AdrianS

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List> - anything more standard than that?

2 Answers2