Pair.java

// Thanks to hevy of stackoverflow for this:

class Pair<First, Second> {
    private First first;
    private Second second;

    public Pair(First first, Second second) {
        this.first = first;
        this.second = second;
    }

    public void setFirst(First first) {
        this.first = first;
    }

    public void setSecond(Second second) {
        this.second = second;
    }

    public First getFirst() {
        return first;
    }

    public Second getSecond() {
        return second;
    }

    public void set(First first, Second second) {
        setFirst(first);
        setSecond(second);
    }

    public static <First, Second> Pair<First, Second> createPair(
        First element0, Second element1)
    {
        return new Pair<First, Second>(element0, element1);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Pair pair = (Pair) o;

        if (first != null ? !first.equals(pair.first) : pair.first != null) return false;
        if (second != null ? !second.equals(pair.second) : pair.second != null) return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = first != null ? first.hashCode() : 0;
        result = 31 * result + (second != null ? second.hashCode() : 0);
        return result;
    }
} // Pair class