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. */ import java.io.Serializable; /** * <p>A contiguous range of characters, optionally negated.</p> * * <p>Instances are immutable.</p> * * @author Stephen Colebourne * @author Chris Feldhacker * @author Gary Gregory * @since 1.0 * @version $Id: CharRange.java 471626 2006-11-06 04:02:09Z bayard $ */ public final class CharRange implements Serializable { /** * Required for serialization support. Lang version 2.0. * * @see java.io.Serializable */ private static final long serialVersionUID = 8270183163158333422L; /** The first character, inclusive, in the range. */ private final char start; /** The last character, inclusive, in the range. */ private final char end; /** True if the range is everything except the characters specified. */ private final boolean negated; /** Cached toString. */ private transient String iToString; //----------------------------------------------------------------------- /** * <p>Constructs a <code>CharRange</code> over a single character.</p> * * @param ch only character in this range */ public CharRange(char ch) { this(ch, ch, false); } /** * <p>Constructs a <code>CharRange</code> over a single character, * optionally negating the range.</p> * * <p>A negated range includes everything except the specified char.</p> * * @param ch only character in this range * @param negated true to express everything except the range */ public CharRange(char ch, boolean negated) { this(ch, ch, negated); } /** * <p>Constructs a <code>CharRange</code> over a set of characters.</p> * * @param start first character, inclusive, in this range * @param end last character, inclusive, in this range */ public CharRange(char start, char end) { this(start, end, false); } /** * <p>Constructs a <code>CharRange</code> over a set of characters, * optionally negating the range.</p> * * <p>A negated range includes everything except that defined by the * start and end characters.</p> * * <p>If start and end are in the wrong order, they are reversed. * Thus <code>a-e</code> is the same as <code>e-a</code>.</p> * * @param start first character, inclusive, in this range * @param end last character, inclusive, in this range * @param negated true to express everything except the range */ public CharRange(char start, char end, boolean negated) { super(); if (start > end) { char temp = start; start = end; end = temp; } this.start = start; this.end = end; this.negated = negated; } // Accessors //----------------------------------------------------------------------- /** * <p>Gets the start character for this character range.</p> * * @return the start char (inclusive) */ public char getStart() { return this.start; } /** * <p>Gets the end character for this character range.</p> * * @return the end char (inclusive) */ public char getEnd() { return this.end; } /** * <p>Is this <code>CharRange</code> negated.</p> * * <p>A negated range includes everything except that defined by the * start and end characters.</p> * * @return <code>true</code> is negated */ public boolean isNegated() { return negated; } // Contains //----------------------------------------------------------------------- /** * <p>Is the character specified contained in this range.</p> * * @param ch the character to check * @return <code>true</code> if this range contains the input character */ public boolean contains(char ch) { return (ch >= start && ch <= end) != negated; } /** * <p>Are all the characters of the passed in range contained in * this range.</p> * * @param range the range to check against * @return <code>true</code> if this range entirely contains the input range * @throws IllegalArgumentException if <code>null</code> input */ public boolean contains(CharRange range) { if (range == null) { throw new IllegalArgumentException("The Range must not be null"); } if (negated) { if (range.negated) { return start >= range.start && end <= range.end; } else { return range.end < start || range.start > end; } } else { if (range.negated) { return start == 0 && end == Character.MAX_VALUE; } else { return start <= range.start && end >= range.end; } } } // Basics //----------------------------------------------------------------------- /** * <p>Compares two CharRange objects, returning true if they represent * exactly the same range of characters defined in the same way.</p> * * @param obj the object to compare to * @return true if equal */ public boolean equals(Object obj) { if (obj == this) { return true; } if (obj instanceof CharRange == false) { return false; } CharRange other = (CharRange) obj; return start == other.start && end == other.end && negated == other.negated; } /** * <p>Gets a hashCode compatible with the equals method.</p> * * @return a suitable hashCode */ public int hashCode() { return 83 + start + 7 * end + (negated ? 1 : 0); } /** * <p>Gets a string representation of the character range.</p> * * @return string representation of this range */ public String toString() { if (iToString == null) { StringBuffer buf = new StringBuffer(4); if (isNegated()) { buf.append('^'); } buf.append(start); if (start != end) { buf.append('-'); buf.append(end); } iToString = buf.toString(); } return iToString; } }