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A library with a number of convenient methods for working with collections

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/**
 * Copyright (C) 2011 Brian Ferris 
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.onebusaway.collections.tuple;

/**
 * A collection of factory methods for creating tuple objects. Tuples are typed
 * ordered collection of objects where individual elements can have distinct
 * types. We currently support a two-member tuple {@link T2} with distinct
 * member types and sub-class {@link Pair} where both member types are the same.
 * 
 * @author bdferris
 * @see T2
 * @see Tuple
 */
public abstract class Tuples {

  private Tuples() {

  }

  /**
   * A convenience factory method for constructing a {@link Pair} object.
   * 
   * @param first the first member of the pair tuple
   * @param second the second member of the pair tuple
   * @return a new {@link Pair} object with the specified members
   */
  public static  Pair pair(T first, T second) {
    return new PairImpl(first, second);
  }

  /**
   * A convenience factory method for constructing a {@link T2} object.
   * 
   * @param first the first member of the tuple
   * @param second the second member of the tuple
   * @return a new {@link T2} object with the specified members
   */
  public static  T2 tuple(S1 first, S2 second) {
    return new T2Impl(first, second);
  }

  /**
   * A convenience method to test for object equality that correctly handles
   * null objects.
   * 
   * @param a the first object to test for equality
   * @param b the second object to test for equality
   * @return true if (a == null && b == null) || (a.equals(b))
   */
  public static final boolean equals(Object a, Object b) {
    return a == null ? (b == null) : (a.equals(b));
  }
}