"implements Serializable"?
-Max
On Mar 31, 2010, at 7:34 AM, joe.da...@oracle.com wrote:
>
>
> On 3/30/2010 10:54 AM, Kevin Bourrillion wrote:
>> Pair is only a partial, flawed solution to a special case (n=2) of a very
>> significant problem: the disproportionate complexity of creating value types
>> in Java. I support addressing the underlying problem in Java 8, and not
>> littering the API with dead-end solutions like Pair.
>
> While I have sympathy with that conclusion, there is the
> side-effect of littering many APIs with the flotsam of lots of different
> classes named "Pair." My inclination would be to produce one adequate
> Pair class in the JDK to prevent the proliferation of yet more Pair classes
> in other code bases.
>
> I should know better than to take the bait, below is a first cut at
> java.util.Pair.
>
> -Joe
>
> package java.util;
>
> import java.util.Objects;
>
> /**
> * An immutable pair of values. The values may be null. The values
> * themselves may be mutable.
> *
> * @param <A> the type of the first element of the pair
> * @param <B> the type of the second element of the pair
> *
> * @since 1.7
> */
> public final class Pair<A, B> {
> private final A a;
> private final B b;
>
> private Pair(A a, B b) {
> this.a = a;
> this.b = b;
> }
>
> /**
> * Returns a pair whose elements are the first and second
> * arguments, respectively.
> * @return a pair constructed from the arguments
> */
> public static <C, D> Pair<C, D> valueOf(C c, D d) {
> // Don't mandate new values.
> return new Pair<C, D>(c, d);
> }
>
> /**
> * Returns the value of the first element of the pair.
> * @return the value of the first element of the pair
> */
> public A getA() {
> return a;
> }
>
> /**
> * Returns the value of the second element of the pair.
> * @return the value of the second element of the pair
> */
> public B getB() {
> return b;
> }
>
> /**
> * TBD
> */
> @Override
> public String toString() {
> return "[" + Objects.toString(a) + ", " + Objects.toString(b) + "]";
> }
>
> /**
> * TBD
> */
> @Override
> public boolean equals(Object x) {
> if (!(x instanceof Pair))
> return false;
> else {
> Pair<?,?> that = (Pair<?,?>) x;
> return
> Objects.equals(this.a, that.a) &&
> Objects.equals(this.b, that.b);
> }
> }
>
> /**
> * TBD
> */
> @Override
> public int hashCode() {
> return Objects.hash(a, b);
> }
> }
