alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (CharSet.java)

This example Java source code file (CharSet.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

a-z, a-za-z, ascii_alpha, ascii_alpha_lower, ascii_alpha_upper, ascii_numeric, charset, empty, hashset, map, object, override, serializable, string, util

The CharSet.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.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * <p>A set of characters.

* * <p>Instances are immutable, but instances of subclasses may not be.

* * <p>#ThreadSafe#

* @since 1.0 */ public class CharSet implements Serializable { /** * Required for serialization support. Lang version 2.0. * * @see java.io.Serializable */ private static final long serialVersionUID = 5947847346149275958L; /** * A CharSet defining no characters. * @since 2.0 */ public static final CharSet EMPTY = new CharSet((String) null); /** * A CharSet defining ASCII alphabetic characters "a-zA-Z". * @since 2.0 */ public static final CharSet ASCII_ALPHA = new CharSet("a-zA-Z"); /** * A CharSet defining ASCII alphabetic characters "a-z". * @since 2.0 */ public static final CharSet ASCII_ALPHA_LOWER = new CharSet("a-z"); /** * A CharSet defining ASCII alphabetic characters "A-Z". * @since 2.0 */ public static final CharSet ASCII_ALPHA_UPPER = new CharSet("A-Z"); /** * A CharSet defining ASCII alphabetic characters "0-9". * @since 2.0 */ public static final CharSet ASCII_NUMERIC = new CharSet("0-9"); /** * A Map of the common cases used in the factory. * Subclasses can add more common patterns if desired * @since 2.0 */ protected static final Map<String, CharSet> COMMON = Collections.synchronizedMap(new HashMap()); static { COMMON.put(null, EMPTY); COMMON.put(StringUtils.EMPTY, EMPTY); COMMON.put("a-zA-Z", ASCII_ALPHA); COMMON.put("A-Za-z", ASCII_ALPHA); COMMON.put("a-z", ASCII_ALPHA_LOWER); COMMON.put("A-Z", ASCII_ALPHA_UPPER); COMMON.put("0-9", ASCII_NUMERIC); } /** The set of CharRange objects. */ private final Set<CharRange> set = Collections.synchronizedSet(new HashSet()); //----------------------------------------------------------------------- /** * <p>Factory method to create a new CharSet using a special syntax.

* * <ul> * <li>{@code null} or empty string ("") * - set containing no characters</li> * <li>Single character, such as "a" * - set containing just that character</li> * <li>Multi character, such as "a-e" * - set containing characters from one character to the other</li> * <li>Negated, such as "^a" or "^a-e" * - set containing all characters except those defined</li> * <li>Combinations, such as "abe-g" * - set containing all the characters from the individual sets</li> * </ul> * * <p>The matching order is:

* <ol> * <li>Negated multi character range, such as "^a-e" * <li>Ordinary multi character range, such as "a-e" * <li>Negated single character, such as "^a" * <li>Ordinary single character, such as "a" * </ol> * * <p>Matching works left to right. Once a match is found the * search starts again from the next character.</p> * * <p>If the same range is defined twice using the same syntax, only * one range will be kept. * Thus, "a-ca-c" creates only one range of "a-c".</p> * * <p>If the start and end of a range are in the wrong order, * they are reversed. Thus "a-e" is the same as "e-a". * As a result, "a-ee-a" would create only one range, * as the "a-e" and "e-a" are the same.</p> * * <p>The set of characters represented is the union of the specified ranges.

* * <p>There are two ways to add a literal negation character ({@code ^}):

* <ul> * <li>As the last character in a string, e.g. {@code CharSet.getInstance("a-z^")} * <li>As a separate element, e.g. {@code CharSet.getInstance("^","a-z")} * </ul> * * <p>Examples using the negation character:

* <pre> * CharSet.getInstance("^a-c").contains('a') = false * CharSet.getInstance("^a-c").contains('d') = true * CharSet.getInstance("^^a-c").contains('a') = true // (only '^' is negated) * CharSet.getInstance("^^a-c").contains('^') = false * CharSet.getInstance("^a-cd-f").contains('d') = true * CharSet.getInstance("a-c^").contains('^') = true * CharSet.getInstance("^", "a-c").contains('^') = true * </pre> * * <p>All CharSet objects returned by this method will be immutable.

* * @param setStrs Strings to merge into the set, may be null * @return a CharSet instance * @since 2.4 */ public static CharSet getInstance(final String... setStrs) { if (setStrs == null) { return null; } if (setStrs.length == 1) { final CharSet common = COMMON.get(setStrs[0]); if (common != null) { return common; } } return new CharSet(setStrs); } //----------------------------------------------------------------------- /** * <p>Constructs a new CharSet using the set syntax. * Each string is merged in with the set.</p> * * @param set Strings to merge into the initial set * @throws NullPointerException if set is {@code null} */ protected CharSet(final String... set) { super(); final int sz = set.length; for (int i = 0; i < sz; i++) { add(set[i]); } } //----------------------------------------------------------------------- /** * <p>Add a set definition string to the {@code CharSet}.

* * @param str set definition string */ protected void add(final String str) { if (str == null) { return; } final int len = str.length(); int pos = 0; while (pos < len) { final int remainder = len - pos; if (remainder >= 4 && str.charAt(pos) == '^' && str.charAt(pos + 2) == '-') { // negated range set.add(CharRange.isNotIn(str.charAt(pos + 1), str.charAt(pos + 3))); pos += 4; } else if (remainder >= 3 && str.charAt(pos + 1) == '-') { // range set.add(CharRange.isIn(str.charAt(pos), str.charAt(pos + 2))); pos += 3; } else if (remainder >= 2 && str.charAt(pos) == '^') { // negated char set.add(CharRange.isNot(str.charAt(pos + 1))); pos += 2; } else { // char set.add(CharRange.is(str.charAt(pos))); pos += 1; } } } //----------------------------------------------------------------------- /** * <p>Gets the internal set as an array of CharRange objects.

* * @return an array of immutable CharRange objects * @since 2.0 */ // NOTE: This is no longer public as CharRange is no longer a public class. // It may be replaced when CharSet moves to Range. /*public*/ CharRange[] getCharRanges() { return set.toArray(new CharRange[set.size()]); } //----------------------------------------------------------------------- /** * <p>Does the {@code CharSet} contain the specified * character {@code ch}.</p> * * @param ch the character to check for * @return {@code true} if the set contains the characters */ public boolean contains(final char ch) { for (final CharRange range : set) { if (range.contains(ch)) { return true; } } return false; } // Basics //----------------------------------------------------------------------- /** * <p>Compares two {@code CharSet} objects, returning true if they represent * exactly the same set of characters defined in the same way.</p> * * <p>The two sets {@code abc} and {@code a-c} are not * equal according to this method.</p> * * @param obj the object to compare to * @return true if equal * @since 2.0 */ @Override public boolean equals(final Object obj) { if (obj == this) { return true; } if (obj instanceof CharSet == false) { return false; } final CharSet other = (CharSet) obj; return set.equals(other.set); } /** * <p>Gets a hash code compatible with the equals method.

* * @return a suitable hash code * @since 2.0 */ @Override public int hashCode() { return 89 + set.hashCode(); } /** * <p>Gets a string representation of the set.

* * @return string representation of the set */ @Override public String toString() { return set.toString(); } }

Other Java examples (source code examples)

Here is a short list of links related to this Java CharSet.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.