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/*
* Copyright (C) 2009 The Android Open Source Project
*
* 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 android.util;
/**
* 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
* objects.
*/
public class Pair<F, S> {
public final F first;
public final S second;
/**
* Constructor for a Pair. If either are null then equals() and hashCode() will throw
* a NullPointerException.
* @param first the first object in the Pair
* @param second the second object in the pair
*/
public Pair(F first, S second) {
this.first = first;
this.second = second;
}
/**
* 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()
*/
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) {
return false;
}
return first.equals(other.first) && second.equals(other.second);
}
/**
* Compute a hash code using the hash codes of the underlying objects
* @return a hashcode of the Pair
*/
public int hashCode() {
int result = 17;
result = 31 * result + first.hashCode();
result = 31 * result + second.hashCode();
return result;
}
/**
* Convenience method for creating an appropriately typed pair.
* @param a the first object in the Pair
* @param b the second object in the pair
* @return a Pair that is templatized with the types of a and b
*/
public static <A, B> Pair <A, B> create(A a, B b) {
return new Pair<A, B>(a, b);
}
}
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