diff options
Diffstat (limited to 'core/java/android/util/Pair.java')
-rw-r--r-- | core/java/android/util/Pair.java | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/core/java/android/util/Pair.java b/core/java/android/util/Pair.java new file mode 100644 index 0000000..bf25306 --- /dev/null +++ b/core/java/android/util/Pair.java @@ -0,0 +1,76 @@ +/* + * 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); + } +} |