Let Pair represent null values.

package android.util;

import libcore.util.Objects;

/**

 * Container to ease passing around a tuple of two objects. This object provides a sensible

 * implementation of equals(), returning true if equals() is true on each of the contained

    public final S second;

    /**

     * Constructor for a Pair. If either are null then equals() and hashCode() will throw

     * a NullPointerException.

     * Constructor for a Pair.

     *

     * @param first the first object in the Pair

     * @param second the second object in the pair

     */

    }

    /**

     * Checks the two objects for equality by delegating to their respective equals() methods.

     * @param o the Pair to which this one is to be checked for equality

     * @return true if the underlying objects of the Pair are both considered equals()

     * Checks the two objects for equality by delegating to their respective

     * {@link Object#equals(Object)} methods.

     *

     * @param o the {@link Pair} to which this one is to be checked for equality

     * @return true if the underlying objects of the Pair are both considered

     *         equal

     */

    @Override

    public boolean equals(Object o) {

        if (o == this) return true;

        if (!(o instanceof Pair)) return false;

        final Pair<F, S> other;

        try {

            other = (Pair<F, S>) o;

        } catch (ClassCastException e) {

        if (!(o instanceof Pair)) {

            return false;

        }

        return first.equals(other.first) && second.equals(other.second);

        Pair<?, ?> p = (Pair<?, ?>) o;

        return Objects.equal(p.first, first) && Objects.equal(p.second, second);

    }

    /**

     * Compute a hash code using the hash codes of the underlying objects

     *

     * @return a hashcode of the Pair

     */

    @Override

    public int hashCode() {

        int result = 17;

        result = 31 * result + first.hashCode();

        result = 31 * result + second.hashCode();

        return result;

        return (first == null ? 0 : first.hashCode()) ^ (second == null ? 0 : second.hashCode());

    }

    /**