Java tutorial
/* * 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.lang.math; import java.io.Serializable; /** * <p><code>NumberRange</code> represents an inclusive range of * {@link java.lang.Number} objects of the same type.</p> * * @author <a href="mailto:chrise@esha.com">Christopher Elkins</a> * @author Stephen Colebourne * @since 2.0 (previously in org.apache.commons.lang) * @version $Id: NumberRange.java 437554 2006-08-28 06:21:41Z bayard $ */ public final class NumberRange extends Range implements Serializable { /** * Required for serialization support. * * @see java.io.Serializable */ private static final long serialVersionUID = 71849363892710L; /** * The minimum number in this range. */ private final Number min; /** * The maximum number in this range. */ private final Number max; /** * Cached output hashCode (class is immutable). */ private transient int hashCode = 0; /** * Cached output toString (class is immutable). */ private transient String toString = null; /** * <p>Constructs a new <code>NumberRange</code> using the specified * number as both the minimum and maximum in this range.</p> * * @param num the number to use for this range * @throws IllegalArgumentException if the number is <code>null</code> * @throws IllegalArgumentException if the number doesn't implement <code>Comparable</code> * @throws IllegalArgumentException if the number is <code>Double.NaN</code> or <code>Float.NaN</code> */ public NumberRange(Number num) { if (num == null) { throw new IllegalArgumentException("The number must not be null"); } if (num instanceof Comparable == false) { throw new IllegalArgumentException("The number must implement Comparable"); } if (num instanceof Double && ((Double) num).isNaN()) { throw new IllegalArgumentException("The number must not be NaN"); } if (num instanceof Float && ((Float) num).isNaN()) { throw new IllegalArgumentException("The number must not be NaN"); } this.min = num; this.max = num; } /** * <p>Constructs a new <code>NumberRange</code> with the specified * minimum and maximum numbers (both inclusive).</p> * * <p>The arguments may be passed in the order (min,max) or (max,min). The * {@link #getMinimumNumber()} and {@link #getMaximumNumber()} methods will return the * correct value.</p> * * <p>This constructor is designed to be used with two <code>Number</code> * objects of the same type. If two objects of different types are passed in, * an exception is thrown.</p> * * @param num1 first number that defines the edge of the range, inclusive * @param num2 second number that defines the edge of the range, inclusive * @throws IllegalArgumentException if either number is <code>null</code> * @throws IllegalArgumentException if the numbers are of different types * @throws IllegalArgumentException if the numbers don't implement <code>Comparable</code> */ public NumberRange(Number num1, Number num2) { if (num1 == null || num2 == null) { throw new IllegalArgumentException("The numbers must not be null"); } if (num1.getClass() != num2.getClass()) { throw new IllegalArgumentException("The numbers must be of the same type"); } if (num1 instanceof Comparable == false) { throw new IllegalArgumentException("The numbers must implement Comparable"); } if (num1 instanceof Double) { if (((Double) num1).isNaN() || ((Double) num2).isNaN()) { throw new IllegalArgumentException("The number must not be NaN"); } } else if (num1 instanceof Float) { if (((Float) num1).isNaN() || ((Float) num2).isNaN()) { throw new IllegalArgumentException("The number must not be NaN"); } } int compare = ((Comparable) num1).compareTo(num2); if (compare == 0) { this.min = num1; this.max = num1; } else if (compare > 0) { this.min = num2; this.max = num1; } else { this.min = num1; this.max = num2; } } // Accessors //-------------------------------------------------------------------- /** * <p>Returns the minimum number in this range.</p> * * @return the minimum number in this range */ public Number getMinimumNumber() { return min; } /** * <p>Returns the maximum number in this range.</p> * * @return the maximum number in this range */ public Number getMaximumNumber() { return max; } // Tests //-------------------------------------------------------------------- /** * <p>Tests whether the specified <code>number</code> occurs within * this range.</p> * * <p><code>null</code> is handled and returns <code>false</code>.</p> * * @param number the number to test, may be <code>null</code> * @return <code>true</code> if the specified number occurs within this range * @throws IllegalArgumentException if the number is of a different type to the range */ public boolean containsNumber(Number number) { if (number == null) { return false; } if (number.getClass() != min.getClass()) { throw new IllegalArgumentException("The number must be of the same type as the range numbers"); } int compareMin = ((Comparable) min).compareTo(number); int compareMax = ((Comparable) max).compareTo(number); return compareMin <= 0 && compareMax >= 0; } // Range tests //-------------------------------------------------------------------- // use Range implementations // Basics //-------------------------------------------------------------------- /** * <p>Compares this range to another object to test if they are equal.</p>. * * <p>To be equal, the class, minimum and maximum must be equal.</p> * * @param obj the reference object with which to compare * @return <code>true</code> if this object is equal */ public boolean equals(Object obj) { if (obj == this) { return true; } if (obj instanceof NumberRange == false) { return false; } NumberRange range = (NumberRange) obj; return min.equals(range.min) && max.equals(range.max); } /** * <p>Gets a hashCode for the range.</p> * * @return a hash code value for this object */ public int hashCode() { if (hashCode == 0) { hashCode = 17; hashCode = 37 * hashCode + getClass().hashCode(); hashCode = 37 * hashCode + min.hashCode(); hashCode = 37 * hashCode + max.hashCode(); } return hashCode; } /** * <p>Gets the range as a <code>String</code>.</p> * * <p>The format of the String is 'Range[<i>min</i>,<i>max</i>]'.</p> * * @return the <code>String</code> representation of this range */ public String toString() { if (toString == null) { StringBuffer buf = new StringBuffer(32); buf.append("Range["); buf.append(min); buf.append(','); buf.append(max); buf.append(']'); toString = buf.toString(); } return toString; } }