77 lines
2.5 KiB
Java
77 lines
2.5 KiB
Java
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/*
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* Copyright (C) 2009 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.util;
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/**
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* Container to ease passing around a tuple of two objects. This object provides a sensible
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* implementation of equals(), returning true if equals() is true on each of the contained
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* objects.
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*/
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public class Pair<F, S> {
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public final F first;
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public final S second;
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/**
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* Constructor for a Pair. If either are null then equals() and hashCode() will throw
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* a NullPointerException.
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* @param first the first object in the Pair
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* @param second the second object in the pair
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*/
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public Pair(F first, S second) {
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this.first = first;
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this.second = second;
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}
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/**
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* Checks the two objects for equality by delegating to their respective equals() methods.
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* @param o the Pair to which this one is to be checked for equality
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* @return true if the underlying objects of the Pair are both considered equals()
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*/
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public boolean equals(Object o) {
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if (o == this) return true;
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if (!(o instanceof Pair)) return false;
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final Pair<F, S> other;
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try {
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other = (Pair<F, S>) o;
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} catch (ClassCastException e) {
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return false;
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}
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return first.equals(other.first) && second.equals(other.second);
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}
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/**
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* Compute a hash code using the hash codes of the underlying objects
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* @return a hashcode of the Pair
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*/
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public int hashCode() {
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int result = 17;
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result = 31 * result + first.hashCode();
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result = 31 * result + second.hashCode();
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return result;
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}
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/**
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* Convenience method for creating an appropriately typed pair.
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* @param a the first object in the Pair
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* @param b the second object in the pair
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* @return a Pair that is templatized with the types of a and b
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*/
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public static <A, B> Pair <A, B> create(A a, B b) {
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return new Pair<A, B>(a, b);
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}
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}
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