636 lines
17 KiB
Java
636 lines
17 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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/**
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* <p>
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* Operations on char primitives and Character objects.
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* </p>
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*
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* <p>
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* This class tries to handle {@code null} input gracefully. An exception will
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* not be thrown for a {@code null} input. Each method documents its behavior in
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* more detail.
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* </p>
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*
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* <p>
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* #ThreadSafe#
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* </p>
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*
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* @since 2.1
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*/
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public class CharUtils {
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private static final String[] CHAR_STRING_ARRAY = new String[128];
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private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
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'e', 'f' };
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/**
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* Linefeed character LF ({@code '\n'}, Unicode 000a).
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*
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* @see <a href=
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* "http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.10.6">JLF:
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* Escape Sequences for Character and String Literals</a>
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* @since 2.2
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*/
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public static final char LF = '\n';
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/**
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* Carriage return characterf CR ('\r', Unicode 000d).
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*
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* @see <a href=
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* "http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.10.6">JLF:
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* Escape Sequences for Character and String Literals</a>
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* @since 2.2
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*/
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public static final char CR = '\r';
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/**
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* {@code \u0000} null control character ('\0'), abbreviated NUL.
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*
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* @since 3.6
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*/
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public static final char NUL = '\0';
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static {
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for (char c = 0; c < CHAR_STRING_ARRAY.length; c++) {
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CHAR_STRING_ARRAY[c] = String.valueOf(c);
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}
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}
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/**
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* <p>
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* {@code CharUtils} instances should NOT be constructed in standard
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* programming. Instead, the class should be used as
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* {@code CharUtils.toString('c');}.
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* </p>
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*
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* <p>
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* This constructor is public to permit tools that require a JavaBean instance
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* to operate.
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* </p>
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*/
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public CharUtils() {
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}
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// -----------------------------------------------------------------------
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/**
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* <p>
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* Converts the character to a Character.
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* </p>
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*
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* <p>
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* For ASCII 7 bit characters, this uses a cache that will return the same
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* Character object each time.
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* </p>
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*
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* <pre>
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* CharUtils.toCharacterObject(' ') = ' '
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* CharUtils.toCharacterObject('A') = 'A'
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* </pre>
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*
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* @deprecated Java 5 introduced {@link Character#valueOf(char)} which caches
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* chars 0 through 127.
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* @param ch the character to convert
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* @return a Character of the specified character
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*/
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@Deprecated
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public static Character toCharacterObject(final char ch) {
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return Character.valueOf(ch);
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}
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/**
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* <p>
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* Converts the String to a Character using the first character, returning null
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* for empty Strings.
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* </p>
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*
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* <p>
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* For ASCII 7 bit characters, this uses a cache that will return the same
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* Character object each time.
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* </p>
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*
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* <pre>
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* CharUtils.toCharacterObject(null) = null
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* CharUtils.toCharacterObject("") = null
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* CharUtils.toCharacterObject("A") = 'A'
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* CharUtils.toCharacterObject("BA") = 'B'
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* </pre>
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*
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* @param str the character to convert
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* @return the Character value of the first letter of the String
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*/
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public static Character toCharacterObject(final String str) {
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if (StringUtils.isEmpty(str)) {
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return null;
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}
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return Character.valueOf(str.charAt(0));
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}
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// -----------------------------------------------------------------------
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/**
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* <p>
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* Converts the Character to a char throwing an exception for {@code null}.
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* </p>
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*
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* <pre>
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* CharUtils.toChar(' ') = ' '
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* CharUtils.toChar('A') = 'A'
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* CharUtils.toChar(null) throws IllegalArgumentException
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* </pre>
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*
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* @param ch the character to convert
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* @return the char value of the Character
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* @throws NullPointerException if the Character is null
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*/
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public static char toChar(final Character ch) {
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Validate.notNull(ch, "ch");
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return ch.charValue();
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}
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/**
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* <p>
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* Converts the Character to a char handling {@code null}.
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* </p>
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*
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* <pre>
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* CharUtils.toChar(null, 'X') = 'X'
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* CharUtils.toChar(' ', 'X') = ' '
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* CharUtils.toChar('A', 'X') = 'A'
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* </pre>
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*
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* @param ch the character to convert
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* @param defaultValue the value to use if the Character is null
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* @return the char value of the Character or the default if null
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*/
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public static char toChar(final Character ch, final char defaultValue) {
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if (ch == null) {
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return defaultValue;
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}
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return ch.charValue();
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}
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// -----------------------------------------------------------------------
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/**
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* <p>
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* Converts the String to a char using the first character, throwing an
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* exception on empty Strings.
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* </p>
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*
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* <pre>
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* CharUtils.toChar("A") = 'A'
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* CharUtils.toChar("BA") = 'B'
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* CharUtils.toChar(null) throws IllegalArgumentException
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* CharUtils.toChar("") throws IllegalArgumentException
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* </pre>
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*
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* @param str the character to convert
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* @return the char value of the first letter of the String
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* @throws NullPointerException if the string is null
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* @throws IllegalArgumentException if the String is empty
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*/
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public static char toChar(final String str) {
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Validate.notEmpty(str, "The String must not be empty");
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return str.charAt(0);
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}
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/**
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* <p>
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* Converts the String to a char using the first character, defaulting the value
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* on empty Strings.
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* </p>
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*
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* <pre>
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* CharUtils.toChar(null, 'X') = 'X'
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* CharUtils.toChar("", 'X') = 'X'
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* CharUtils.toChar("A", 'X') = 'A'
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* CharUtils.toChar("BA", 'X') = 'B'
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* </pre>
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*
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* @param str the character to convert
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* @param defaultValue the value to use if the Character is null
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* @return the char value of the first letter of the String or the default if
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* null
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*/
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public static char toChar(final String str, final char defaultValue) {
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if (StringUtils.isEmpty(str)) {
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return defaultValue;
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}
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return str.charAt(0);
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}
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// -----------------------------------------------------------------------
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/**
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* <p>
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* Converts the character to the Integer it represents, throwing an exception if
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* the character is not numeric.
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* </p>
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*
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* <p>
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* This method converts the char '1' to the int 1 and so on.
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* </p>
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*
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* <pre>
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* CharUtils.toIntValue('3') = 3
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* CharUtils.toIntValue('A') throws IllegalArgumentException
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* </pre>
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*
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* @param ch the character to convert
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* @return the int value of the character
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* @throws IllegalArgumentException if the character is not ASCII numeric
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*/
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public static int toIntValue(final char ch) {
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if (!isAsciiNumeric(ch)) {
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throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'");
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}
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return ch - 48;
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}
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/**
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* <p>
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* Converts the character to the Integer it represents, throwing an exception if
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* the character is not numeric.
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* </p>
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*
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* <p>
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* This method converts the char '1' to the int 1 and so on.
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* </p>
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*
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* <pre>
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* CharUtils.toIntValue('3', -1) = 3
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* CharUtils.toIntValue('A', -1) = -1
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* </pre>
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*
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* @param ch the character to convert
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* @param defaultValue the default value to use if the character is not numeric
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* @return the int value of the character
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*/
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public static int toIntValue(final char ch, final int defaultValue) {
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if (!isAsciiNumeric(ch)) {
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return defaultValue;
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}
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return ch - 48;
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}
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/**
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* <p>
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* Converts the character to the Integer it represents, throwing an exception if
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* the character is not numeric.
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* </p>
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*
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* <p>
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* This method converts the char '1' to the int 1 and so on.
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* </p>
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*
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* <pre>
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* CharUtils.toIntValue('3') = 3
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* CharUtils.toIntValue(null) throws IllegalArgumentException
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* CharUtils.toIntValue('A') throws IllegalArgumentException
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* </pre>
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*
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* @param ch the character to convert, not null
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* @return the int value of the character
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* @throws NullPointerException if the Character is null
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* @throws IllegalArgumentException if the Character is not ASCII numeric
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*/
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public static int toIntValue(final Character ch) {
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Validate.notNull(ch, "ch");
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return toIntValue(ch.charValue());
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}
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/**
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* <p>
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* Converts the character to the Integer it represents, throwing an exception if
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* the character is not numeric.
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* </p>
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*
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* <p>
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* This method converts the char '1' to the int 1 and so on.
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* </p>
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*
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* <pre>
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* CharUtils.toIntValue(null, -1) = -1
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* CharUtils.toIntValue('3', -1) = 3
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* CharUtils.toIntValue('A', -1) = -1
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* </pre>
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*
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* @param ch the character to convert
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* @param defaultValue the default value to use if the character is not numeric
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* @return the int value of the character
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*/
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public static int toIntValue(final Character ch, final int defaultValue) {
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if (ch == null) {
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return defaultValue;
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}
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return toIntValue(ch.charValue(), defaultValue);
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}
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// -----------------------------------------------------------------------
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/**
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* <p>
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* Converts the character to a String that contains the one character.
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* </p>
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*
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* <p>
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* For ASCII 7 bit characters, this uses a cache that will return the same
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* String object each time.
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* </p>
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*
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* <pre>
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* CharUtils.toString(' ') = " "
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* CharUtils.toString('A') = "A"
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* </pre>
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*
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* @param ch the character to convert
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* @return a String containing the one specified character
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*/
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public static String toString(final char ch) {
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if (ch < 128) {
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return CHAR_STRING_ARRAY[ch];
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}
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return new String(new char[] { ch });
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}
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/**
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* <p>
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* Converts the character to a String that contains the one character.
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* </p>
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*
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* <p>
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* For ASCII 7 bit characters, this uses a cache that will return the same
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* String object each time.
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* </p>
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*
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* <p>
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* If {@code null} is passed in, {@code null} will be returned.
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* </p>
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*
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* <pre>
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* CharUtils.toString(null) = null
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* CharUtils.toString(' ') = " "
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* CharUtils.toString('A') = "A"
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* </pre>
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*
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* @param ch the character to convert
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* @return a String containing the one specified character
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*/
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public static String toString(final Character ch) {
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if (ch == null) {
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return null;
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}
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return toString(ch.charValue());
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}
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// --------------------------------------------------------------------------
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/**
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* <p>
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* Converts the string to the Unicode format '\u0020'.
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* </p>
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*
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* <p>
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* This format is the Java source code format.
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* </p>
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*
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* <pre>
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* CharUtils.unicodeEscaped(' ') = "\u0020"
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* CharUtils.unicodeEscaped('A') = "\u0041"
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* </pre>
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*
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* @param ch the character to convert
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* @return the escaped Unicode string
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*/
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public static String unicodeEscaped(final char ch) {
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return "\\u" + HEX_DIGITS[(ch >> 12) & 15] + HEX_DIGITS[(ch >> 8) & 15] + HEX_DIGITS[(ch >> 4) & 15]
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+ HEX_DIGITS[(ch) & 15];
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}
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/**
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* <p>
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* Converts the string to the Unicode format '\u0020'.
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* </p>
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*
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* <p>
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* This format is the Java source code format.
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* </p>
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*
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* <p>
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* If {@code null} is passed in, {@code null} will be returned.
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* </p>
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*
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* <pre>
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* CharUtils.unicodeEscaped(null) = null
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* CharUtils.unicodeEscaped(' ') = "\u0020"
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* CharUtils.unicodeEscaped('A') = "\u0041"
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* </pre>
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*
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* @param ch the character to convert, may be null
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* @return the escaped Unicode string, null if null input
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*/
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public static String unicodeEscaped(final Character ch) {
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if (ch == null) {
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return null;
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}
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return unicodeEscaped(ch.charValue());
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}
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// --------------------------------------------------------------------------
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/**
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* <p>
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* Checks whether the character is ASCII 7 bit.
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* </p>
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*
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* <pre>
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* CharUtils.isAscii('a') = true
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* CharUtils.isAscii('A') = true
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* CharUtils.isAscii('3') = true
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* CharUtils.isAscii('-') = true
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* CharUtils.isAscii('\n') = true
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* CharUtils.isAscii('©') = false
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* </pre>
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*
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* @param ch the character to check
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* @return true if less than 128
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*/
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public static boolean isAscii(final char ch) {
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return ch < 128;
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}
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/**
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* <p>
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* Checks whether the character is ASCII 7 bit printable.
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* </p>
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*
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* <pre>
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* CharUtils.isAsciiPrintable('a') = true
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* CharUtils.isAsciiPrintable('A') = true
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* CharUtils.isAsciiPrintable('3') = true
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* CharUtils.isAsciiPrintable('-') = true
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* CharUtils.isAsciiPrintable('\n') = false
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* CharUtils.isAsciiPrintable('©') = false
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* </pre>
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*
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* @param ch the character to check
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* @return true if between 32 and 126 inclusive
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*/
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public static boolean isAsciiPrintable(final char ch) {
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return ch >= 32 && ch < 127;
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}
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/**
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* <p>
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* Checks whether the character is ASCII 7 bit control.
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* </p>
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*
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* <pre>
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* CharUtils.isAsciiControl('a') = false
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* CharUtils.isAsciiControl('A') = false
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* CharUtils.isAsciiControl('3') = false
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* CharUtils.isAsciiControl('-') = false
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* CharUtils.isAsciiControl('\n') = true
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* CharUtils.isAsciiControl('©') = false
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* </pre>
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*
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* @param ch the character to check
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* @return true if less than 32 or equals 127
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*/
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public static boolean isAsciiControl(final char ch) {
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return ch < 32 || ch == 127;
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}
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/**
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* <p>
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* Checks whether the character is ASCII 7 bit alphabetic.
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* </p>
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*
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* <pre>
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* CharUtils.isAsciiAlpha('a') = true
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* CharUtils.isAsciiAlpha('A') = true
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* CharUtils.isAsciiAlpha('3') = false
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* CharUtils.isAsciiAlpha('-') = false
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* CharUtils.isAsciiAlpha('\n') = false
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* CharUtils.isAsciiAlpha('©') = false
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* </pre>
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*
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* @param ch the character to check
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* @return true if between 65 and 90 or 97 and 122 inclusive
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*/
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public static boolean isAsciiAlpha(final char ch) {
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return isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch);
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}
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/**
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* <p>
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* Checks whether the character is ASCII 7 bit alphabetic upper case.
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* </p>
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*
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* <pre>
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* CharUtils.isAsciiAlphaUpper('a') = false
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* CharUtils.isAsciiAlphaUpper('A') = true
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* CharUtils.isAsciiAlphaUpper('3') = false
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* CharUtils.isAsciiAlphaUpper('-') = false
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* CharUtils.isAsciiAlphaUpper('\n') = false
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* CharUtils.isAsciiAlphaUpper('©') = false
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* </pre>
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*
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* @param ch the character to check
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* @return true if between 65 and 90 inclusive
|
|
*/
|
|
public static boolean isAsciiAlphaUpper(final char ch) {
|
|
return ch >= 'A' && ch <= 'Z';
|
|
}
|
|
|
|
/**
|
|
* <p>
|
|
* Checks whether the character is ASCII 7 bit alphabetic lower case.
|
|
* </p>
|
|
*
|
|
* <pre>
|
|
* CharUtils.isAsciiAlphaLower('a') = true
|
|
* CharUtils.isAsciiAlphaLower('A') = false
|
|
* CharUtils.isAsciiAlphaLower('3') = false
|
|
* CharUtils.isAsciiAlphaLower('-') = false
|
|
* CharUtils.isAsciiAlphaLower('\n') = false
|
|
* CharUtils.isAsciiAlphaLower('©') = false
|
|
* </pre>
|
|
*
|
|
* @param ch the character to check
|
|
* @return true if between 97 and 122 inclusive
|
|
*/
|
|
public static boolean isAsciiAlphaLower(final char ch) {
|
|
return ch >= 'a' && ch <= 'z';
|
|
}
|
|
|
|
/**
|
|
* <p>
|
|
* Checks whether the character is ASCII 7 bit numeric.
|
|
* </p>
|
|
*
|
|
* <pre>
|
|
* CharUtils.isAsciiNumeric('a') = false
|
|
* CharUtils.isAsciiNumeric('A') = false
|
|
* CharUtils.isAsciiNumeric('3') = true
|
|
* CharUtils.isAsciiNumeric('-') = false
|
|
* CharUtils.isAsciiNumeric('\n') = false
|
|
* CharUtils.isAsciiNumeric('©') = false
|
|
* </pre>
|
|
*
|
|
* @param ch the character to check
|
|
* @return true if between 48 and 57 inclusive
|
|
*/
|
|
public static boolean isAsciiNumeric(final char ch) {
|
|
return ch >= '0' && ch <= '9';
|
|
}
|
|
|
|
/**
|
|
* <p>
|
|
* Checks whether the character is ASCII 7 bit numeric.
|
|
* </p>
|
|
*
|
|
* <pre>
|
|
* CharUtils.isAsciiAlphanumeric('a') = true
|
|
* CharUtils.isAsciiAlphanumeric('A') = true
|
|
* CharUtils.isAsciiAlphanumeric('3') = true
|
|
* CharUtils.isAsciiAlphanumeric('-') = false
|
|
* CharUtils.isAsciiAlphanumeric('\n') = false
|
|
* CharUtils.isAsciiAlphanumeric('©') = false
|
|
* </pre>
|
|
*
|
|
* @param ch the character to check
|
|
* @return true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive
|
|
*/
|
|
public static boolean isAsciiAlphanumeric(final char ch) {
|
|
return isAsciiAlpha(ch) || isAsciiNumeric(ch);
|
|
}
|
|
|
|
/**
|
|
* <p>
|
|
* Compares two {@code char} values numerically. This is the same functionality
|
|
* as provided in Java 7.
|
|
* </p>
|
|
*
|
|
* @param x the first {@code char} to compare
|
|
* @param y the second {@code char} to compare
|
|
* @return the value {@code 0} if {@code x == y}; a value less than {@code 0} if
|
|
* {@code x < y}; and a value greater than {@code 0} if {@code x > y}
|
|
* @since 3.4
|
|
*/
|
|
public static int compare(final char x, final char y) {
|
|
return x - y;
|
|
}
|
|
}
|