Pair.java

package org.bigtop.bigpetstore.util;

import java.util.Comparator;

import org.bigtop.bigpetstore.generator.TransactionIteratorFactory;
/**
 * Borrowed from MRUnit.  No need to add the whole jar to the classpath just for this 
 * object.  Really only by {@link TransactionIteratorFactory}.
 * 
 * Deprecated because, eventually, we want to add guava or some other high-tech collections library
 * to the classpath and use DistributedCache deployer for it , rather than bundling source for stuff
 * like this.
 */
@Deprecated
public class Pair<S, T> implements Comparable<Pair<S, T>> {

  private final S first;
  private final T second;

  public Pair(final S car, final T cdr) {
    first = car;
    second = cdr;
  }

  public S getFirst() { return first; }
  public T getSecond() { return second; }

  @Override
  public boolean equals(Object o) {
    if (null == o) {
      return false;
    } else if (o instanceof Pair) {
      Pair<S, T> p = (Pair<S, T>) o;
      if (first == null && second == null) {
        return p.first == null && p.second == null;
      } else if (first == null) {
        return p.first == null && second.equals(p.second);
      } else if (second == null) {
        return p.second == null && first.equals(p.first);
      } else {
        return first.equals(p.first) && second.equals(p.second);
      }
    } else {
      return false;
    }
  }

  @Override
  public int hashCode() {
    int code = 0;

    if (null != first) {
      code += first.hashCode();
    }

    if (null != second) {
      code += second.hashCode() << 1;
    }

    return code;
  }

  @Override
  public int compareTo(Pair<S, T> p) {
    if (null == p) {
      return 1;
    }

    Comparable<S> firstCompare = (Comparable<S>) first;

    int firstResult = firstCompare.compareTo(p.first);
    if (firstResult == 0) {
      Comparable<T> secondCompare = (Comparable<T>) second;
      return secondCompare.compareTo(p.second);
    } else {
      return firstResult;
    }
  }

  // TODO: Can this be made static? Same with SecondElemComparator?
  public class FirstElemComparator implements Comparator<Pair<S, T>> {
    public FirstElemComparator() {
    }

    public int compare(Pair<S, T> p1, Pair<S, T> p2) {
      Comparable<S> cS = (Comparable<S>) p1.first;
      return cS.compareTo(p2.first);
    }
  }

  public class SecondElemComparator implements Comparator<Pair<S, T>> {
    public SecondElemComparator() {
    }

    public int compare(Pair<S, T> p1, Pair<S, T> p2) {
      Comparable<T> cT = (Comparable<T>) p1.second;
      return cT.compareTo(p2.second);
    }
  }

  @Override
  public String toString() {
    String firstString = "null";
    String secondString = "null";

    if (null != first) {
      firstString = first.toString();
    }

    if (null != second) {
      secondString = second.toString();
    }

    return "(" + firstString + ", " + secondString + ")";
  }
}