513 lines
18 KiB
Java
513 lines
18 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. 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 org.apache.commons.lang3;
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import java.io.Serializable;
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import java.util.Comparator;
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/**
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* <p>An immutable range of objects from a minimum to maximum point inclusive.</p>
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*
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* <p>The objects need to either be implementations of {@code Comparable}
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* or you need to supply a {@code Comparator}. </p>
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*
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* <p>#ThreadSafe# if the objects and comparator are thread-safe</p>
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*
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* @param <T> The type of range values.
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* @since 3.0
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*/
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public final class Range<T> implements Serializable {
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@SuppressWarnings({"rawtypes", "unchecked"})
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private enum ComparableComparator implements Comparator {
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INSTANCE;
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/**
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* Comparable based compare implementation.
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*
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* @param obj1 left hand side of comparison
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* @param obj2 right hand side of comparison
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* @return negative, 0, positive comparison value
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*/
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@Override
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public int compare(final Object obj1, final Object obj2) {
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return ((Comparable) obj1).compareTo(obj2);
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}
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}
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/**
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* Serialization version.
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* @see java.io.Serializable
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*/
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private static final long serialVersionUID = 1L;
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/**
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* <p>Obtains a range with the specified minimum and maximum values (both inclusive).</p>
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*
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* <p>The range uses the natural ordering of the elements to determine where
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* values lie in the range.</p>
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*
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* <p>The arguments may be passed in the order (min,max) or (max,min).
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* The getMinimum and getMaximum methods will return the correct values.</p>
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*
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* @param <T> the type of the elements in this range
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* @param fromInclusive the first value that defines the edge of the range, inclusive
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* @param toInclusive the second value that defines the edge of the range, inclusive
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* @return the range object, not null
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* @throws IllegalArgumentException if either element is null
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* @throws ClassCastException if the elements are not {@code Comparable}
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*/
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public static <T extends Comparable<T>> Range<T> between(final T fromInclusive, final T toInclusive) {
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return between(fromInclusive, toInclusive, null);
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}
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/**
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* <p>Obtains a range with the specified minimum and maximum values (both inclusive).</p>
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*
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* <p>The range uses the specified {@code Comparator} to determine where
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* values lie in the range.</p>
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*
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* <p>The arguments may be passed in the order (min,max) or (max,min).
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* The getMinimum and getMaximum methods will return the correct values.</p>
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*
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* @param <T> the type of the elements in this range
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* @param fromInclusive the first value that defines the edge of the range, inclusive
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* @param toInclusive the second value that defines the edge of the range, inclusive
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* @param comparator the comparator to be used, null for natural ordering
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* @return the range object, not null
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* @throws IllegalArgumentException if either element is null
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* @throws ClassCastException if using natural ordering and the elements are not {@code Comparable}
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*/
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public static <T> Range<T> between(final T fromInclusive, final T toInclusive, final Comparator<T> comparator) {
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return new Range<>(fromInclusive, toInclusive, comparator);
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}
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/**
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* <p>Obtains a range using the specified element as both the minimum
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* and maximum in this range.</p>
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*
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* <p>The range uses the natural ordering of the elements to determine where
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* values lie in the range.</p>
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*
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* @param <T> the type of the elements in this range
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* @param element the value to use for this range, not null
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* @return the range object, not null
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* @throws IllegalArgumentException if the element is null
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* @throws ClassCastException if the element is not {@code Comparable}
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*/
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public static <T extends Comparable<T>> Range<T> is(final T element) {
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return between(element, element, null);
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}
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/**
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* <p>Obtains a range using the specified element as both the minimum
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* and maximum in this range.</p>
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*
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* <p>The range uses the specified {@code Comparator} to determine where
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* values lie in the range.</p>
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*
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* @param <T> the type of the elements in this range
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* @param element the value to use for this range, must not be {@code null}
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* @param comparator the comparator to be used, null for natural ordering
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* @return the range object, not null
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* @throws IllegalArgumentException if the element is null
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* @throws ClassCastException if using natural ordering and the elements are not {@code Comparable}
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*/
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public static <T> Range<T> is(final T element, final Comparator<T> comparator) {
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return between(element, element, comparator);
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}
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/**
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* The ordering scheme used in this range.
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*/
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private final Comparator<T> comparator;
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/**
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* Cached output hashCode (class is immutable).
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*/
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private transient int hashCode;
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/**
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* The maximum value in this range (inclusive).
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*/
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private final T maximum;
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/**
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* The minimum value in this range (inclusive).
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*/
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private final T minimum;
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/**
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* Cached output toString (class is immutable).
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*/
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private transient String toString;
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/**
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* Creates an instance.
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*
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* @param element1 the first element, not null
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* @param element2 the second element, not null
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* @param comp the comparator to be used, null for natural ordering
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*/
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@SuppressWarnings("unchecked")
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private Range(final T element1, final T element2, final Comparator<T> comp) {
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if (element1 == null || element2 == null) {
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throw new IllegalArgumentException("Elements in a range must not be null: element1=" +
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element1 + ", element2=" + element2);
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}
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if (comp == null) {
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this.comparator = ComparableComparator.INSTANCE;
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} else {
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this.comparator = comp;
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}
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if (this.comparator.compare(element1, element2) < 1) {
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this.minimum = element1;
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this.maximum = element2;
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} else {
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this.minimum = element2;
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this.maximum = element1;
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}
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}
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/**
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* <p>Checks whether the specified element occurs within this range.</p>
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*
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* @param element the element to check for, null returns false
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* @return true if the specified element occurs within this range
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*/
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public boolean contains(final T element) {
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if (element == null) {
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return false;
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}
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return comparator.compare(element, minimum) > -1 && comparator.compare(element, maximum) < 1;
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}
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/**
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* <p>Checks whether this range contains all the elements of the specified range.</p>
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*
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* <p>This method may fail if the ranges have two different comparators or element types.</p>
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*
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* @param otherRange the range to check, null returns false
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* @return true if this range contains the specified range
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* @throws RuntimeException if ranges cannot be compared
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*/
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public boolean containsRange(final Range<T> otherRange) {
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if (otherRange == null) {
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return false;
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}
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return contains(otherRange.minimum)
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&& contains(otherRange.maximum);
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}
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/**
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* <p>Checks where the specified element occurs relative to this range.</p>
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*
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* <p>The API is reminiscent of the Comparable interface returning {@code -1} if
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* the element is before the range, {@code 0} if contained within the range and
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* {@code 1} if the element is after the range. </p>
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*
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* @param element the element to check for, not null
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* @return -1, 0 or +1 depending on the element's location relative to the range
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*/
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public int elementCompareTo(final T element) {
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// Comparable API says throw NPE on null
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Validate.notNull(element, "element");
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if (isAfter(element)) {
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return -1;
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} else if (isBefore(element)) {
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return 1;
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} else {
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return 0;
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}
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}
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// Element tests
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//--------------------------------------------------------------------
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/**
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* <p>Compares this range to another object to test if they are equal.</p>.
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*
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* <p>To be equal, the minimum and maximum values must be equal, which
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* ignores any differences in the comparator.</p>
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*
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* @param obj the reference object with which to compare
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* @return true if this object is equal
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*/
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@Override
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public boolean equals(final Object obj) {
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if (obj == this) {
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return true;
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} else if (obj == null || obj.getClass() != getClass()) {
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return false;
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} else {
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@SuppressWarnings("unchecked") // OK because we checked the class above
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final
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Range<T> range = (Range<T>) obj;
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return minimum.equals(range.minimum) &&
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maximum.equals(range.maximum);
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}
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}
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/**
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* <p>Gets the comparator being used to determine if objects are within the range.</p>
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*
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* <p>Natural ordering uses an internal comparator implementation, thus this
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* method never returns null. See {@link #isNaturalOrdering()}.</p>
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*
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* @return the comparator being used, not null
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*/
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public Comparator<T> getComparator() {
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return comparator;
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}
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/**
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* <p>Gets the maximum value in this range.</p>
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*
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* @return the maximum value in this range, not null
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*/
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public T getMaximum() {
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return maximum;
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}
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/**
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* <p>Gets the minimum value in this range.</p>
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*
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* @return the minimum value in this range, not null
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*/
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public T getMinimum() {
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return minimum;
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}
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/**
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* <p>Gets a suitable hash code for the range.</p>
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*
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* @return a hash code value for this object
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*/
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@Override
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public int hashCode() {
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int result = hashCode;
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if (hashCode == 0) {
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result = 17;
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result = 37 * result + getClass().hashCode();
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result = 37 * result + minimum.hashCode();
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result = 37 * result + maximum.hashCode();
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hashCode = result;
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}
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return result;
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}
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/**
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* Calculate the intersection of {@code this} and an overlapping Range.
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* @param other overlapping Range
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* @return range representing the intersection of {@code this} and {@code other} ({@code this} if equal)
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* @throws IllegalArgumentException if {@code other} does not overlap {@code this}
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* @since 3.0.1
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*/
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public Range<T> intersectionWith(final Range<T> other) {
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if (!this.isOverlappedBy(other)) {
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throw new IllegalArgumentException(String.format(
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"Cannot calculate intersection with non-overlapping range %s", other));
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}
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if (this.equals(other)) {
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return this;
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}
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final T min = getComparator().compare(minimum, other.minimum) < 0 ? other.minimum : minimum;
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final T max = getComparator().compare(maximum, other.maximum) < 0 ? maximum : other.maximum;
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return between(min, max, getComparator());
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}
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/**
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* <p>Checks whether this range is after the specified element.</p>
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*
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* @param element the element to check for, null returns false
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* @return true if this range is entirely after the specified element
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*/
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public boolean isAfter(final T element) {
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if (element == null) {
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return false;
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}
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return comparator.compare(element, minimum) < 0;
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}
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/**
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* <p>Checks whether this range is completely after the specified range.</p>
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*
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* <p>This method may fail if the ranges have two different comparators or element types.</p>
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*
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* @param otherRange the range to check, null returns false
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* @return true if this range is completely after the specified range
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* @throws RuntimeException if ranges cannot be compared
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*/
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public boolean isAfterRange(final Range<T> otherRange) {
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if (otherRange == null) {
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return false;
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}
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return isAfter(otherRange.maximum);
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}
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/**
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* <p>Checks whether this range is before the specified element.</p>
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*
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* @param element the element to check for, null returns false
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* @return true if this range is entirely before the specified element
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*/
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public boolean isBefore(final T element) {
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if (element == null) {
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return false;
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}
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return comparator.compare(element, maximum) > 0;
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}
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/**
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* <p>Checks whether this range is completely before the specified range.</p>
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*
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* <p>This method may fail if the ranges have two different comparators or element types.</p>
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*
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* @param otherRange the range to check, null returns false
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* @return true if this range is completely before the specified range
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* @throws RuntimeException if ranges cannot be compared
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*/
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public boolean isBeforeRange(final Range<T> otherRange) {
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if (otherRange == null) {
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return false;
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}
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return isBefore(otherRange.minimum);
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}
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/**
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* <p>Checks whether this range ends with the specified element.</p>
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*
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* @param element the element to check for, null returns false
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* @return true if the specified element occurs within this range
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*/
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public boolean isEndedBy(final T element) {
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if (element == null) {
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return false;
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}
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return comparator.compare(element, maximum) == 0;
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}
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/**
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* <p>Whether or not the Range is using the natural ordering of the elements.</p>
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*
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* <p>Natural ordering uses an internal comparator implementation, thus this
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* method is the only way to check if a null comparator was specified.</p>
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*
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* @return true if using natural ordering
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*/
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public boolean isNaturalOrdering() {
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return comparator == ComparableComparator.INSTANCE;
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}
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/**
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* <p>Checks whether this range is overlapped by the specified range.</p>
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*
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* <p>Two ranges overlap if there is at least one element in common.</p>
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*
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* <p>This method may fail if the ranges have two different comparators or element types.</p>
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*
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* @param otherRange the range to test, null returns false
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* @return true if the specified range overlaps with this
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* range; otherwise, {@code false}
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* @throws RuntimeException if ranges cannot be compared
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*/
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public boolean isOverlappedBy(final Range<T> otherRange) {
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if (otherRange == null) {
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return false;
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}
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return otherRange.contains(minimum)
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|| otherRange.contains(maximum)
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|| contains(otherRange.minimum);
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}
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/**
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* <p>Checks whether this range starts with the specified element.</p>
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*
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* @param element the element to check for, null returns false
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* @return true if the specified element occurs within this range
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*/
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public boolean isStartedBy(final T element) {
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if (element == null) {
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return false;
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}
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return comparator.compare(element, minimum) == 0;
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}
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/**
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* <p>
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* Fits the given element into this range by returning the given element or, if out of bounds, the range minimum if
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* below, or the range maximum if above.
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* </p>
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* <pre>
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* Range<Integer> range = Range.between(16, 64);
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* range.fit(-9) --> 16
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* range.fit(0) --> 16
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* range.fit(15) --> 16
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* range.fit(16) --> 16
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* range.fit(17) --> 17
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* ...
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* range.fit(63) --> 63
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* range.fit(64) --> 64
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* range.fit(99) --> 64
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* </pre>
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* @param element the element to check for, not null
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* @return the minimum, the element, or the maximum depending on the element's location relative to the range
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* @since 3.10
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*/
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public T fit(final T element) {
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// Comparable API says throw NPE on null
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Validate.notNull(element, "element");
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if (isAfter(element)) {
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return minimum;
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} else if (isBefore(element)) {
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return maximum;
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} else {
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return element;
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}
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}
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/**
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* <p>Gets the range as a {@code String}.</p>
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*
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* <p>The format of the String is '[<i>min</i>..<i>max</i>]'.</p>
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*
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* @return the {@code String} representation of this range
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*/
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@Override
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public String toString() {
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if (toString == null) {
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toString = "[" + minimum + ".." + maximum + "]";
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}
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return toString;
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}
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/**
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* <p>Formats the receiver using the given format.</p>
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*
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* <p>This uses {@link java.util.Formattable} to perform the formatting. Three variables may
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* be used to embed the minimum, maximum and comparator.
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* Use {@code %1$s} for the minimum element, {@code %2$s} for the maximum element
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* and {@code %3$s} for the comparator.
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* The default format used by {@code toString()} is {@code [%1$s..%2$s]}.</p>
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*
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* @param format the format string, optionally containing {@code %1$s}, {@code %2$s} and {@code %3$s}, not null
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* @return the formatted string, not null
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*/
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public String toString(final String format) {
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return String.format(format, minimum, maximum, comparator);
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}
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}
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