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