A Java collection of value pairs? (tuples?)

Question

I like how Java has a Map where you can define the types of each entry in the map, for example .

What I\'m looking for is a type

Answer 1

The Pair class is one of those "gimme" generics examples that is easy enough to write on your own. For example, off the top of my head:

public class Pair {

  private final L left;
  private final R right;

  public Pair(L left, R right) {
    assert left != null;
    assert right != null;

    this.left = left;
    this.right = right;
  }

  public L getLeft() { return left; }
  public R getRight() { return right; }

  @Override
  public int hashCode() { return left.hashCode() ^ right.hashCode(); }

  @Override
  public boolean equals(Object o) {
    if (!(o instanceof Pair)) return false;
    Pair pairo = (Pair) o;
    return this.left.equals(pairo.getLeft()) &&
           this.right.equals(pairo.getRight());
  }

}

And yes, this exists in multiple places on the Net, with varying degrees of completeness and feature. (My example above is intended to be immutable.)