org.apache.commons.text.CaseUtils Maven / Gradle / Ivy
Show all versions of commons-text Show documentation
/*
* 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.text;
import org.apache.commons.lang3.StringUtils;
import java.util.HashSet;
import java.util.Set;
/**
* Case manipulation operations on Strings that contain words.
*
* This class tries to handle null input gracefully.
* An exception will not be thrown for a null input.
* Each method documents its behaviour in more detail.
*
* @since 1.2
*/
public class CaseUtils {
/**
* CaseUtils instances should NOT be constructed in
* standard programming. Instead, the class should be used as
* CaseUtils.toCamelCase("foo bar", true, new char[]{'-'});.
*
* This constructor is public to permit tools that require a JavaBean
* instance to operate.
*/
public CaseUtils() {
super();
}
/**
* Converts all the delimiter separated words in a String into camelCase,
* that is each word is made up of a titlecase character and then a series of
* lowercase characters.
*
* The delimiters represent a set of characters understood to separate words.
* The first non-delimiter character after a delimiter will be capitalized. The first String
* character may or may not be capitalized and it's determined by the user input for capitalizeFirstLetter
* variable.
*
* A null input String returns null.
* Capitalization uses the Unicode title case, normally equivalent to
* upper case and cannot perform locale-sensitive mappings.
*
*
* CaseUtils.toCamelCase(null, false) = null
* CaseUtils.toCamelCase("", false, *) = ""
* CaseUtils.toCamelCase(*, false, null) = *
* CaseUtils.toCamelCase(*, true, new char[0]) = *
* CaseUtils.toCamelCase("To.Camel.Case", false, new char[]{'.'}) = "toCamelCase"
* CaseUtils.toCamelCase(" to @ Camel case", true, new char[]{'@'}) = "ToCamelCase"
* CaseUtils.toCamelCase(" @to @ Camel case", false, new char[]{'@'}) = "toCamelCase"
*
*
* @param str the String to be converted to camelCase, may be null
* @param capitalizeFirstLetter boolean that determines if the first character of first word should be title case.
* @param delimiters set of characters to determine capitalization, null and/or empty array means whitespace
* @return camelCase of String, null if null String input
*/
public static String toCamelCase(String str, final boolean capitalizeFirstLetter, final char... delimiters) {
if (StringUtils.isEmpty(str)) {
return str;
}
str = str.toLowerCase();
final int strLen = str.length();
final int[] newCodePoints = new int[strLen];
int outOffset = 0;
final Set delimiterSet = generateDelimiterSet(delimiters);
boolean capitalizeNext = false;
if (capitalizeFirstLetter) {
capitalizeNext = true;
}
for (int index = 0; index < strLen;) {
final int codePoint = str.codePointAt(index);
if (delimiterSet.contains(codePoint)) {
capitalizeNext = true;
if (outOffset == 0) {
capitalizeNext = false;
}
index += Character.charCount(codePoint);
} else if (capitalizeNext || outOffset == 0 && capitalizeFirstLetter) {
final int titleCaseCodePoint = Character.toTitleCase(codePoint);
newCodePoints[outOffset++] = titleCaseCodePoint;
index += Character.charCount(titleCaseCodePoint);
capitalizeNext = false;
} else {
newCodePoints[outOffset++] = codePoint;
index += Character.charCount(codePoint);
}
}
if (outOffset != 0) {
return new String(newCodePoints, 0, outOffset);
}
return str;
}
/**
* Converts an array of delimiters to a hash set of code points. Code point of space(32) is added
* as the default value. The generated hash set provides O(1) lookup time.
*
* @param delimiters set of characters to determine capitalization, null means whitespace
* @return Set
*/
private static Set generateDelimiterSet(final char[] delimiters) {
final Set delimiterHashSet = new HashSet<>();
delimiterHashSet.add(Character.codePointAt(new char[]{' '}, 0));
if (delimiters == null || delimiters.length == 0) {
return delimiterHashSet;
}
for (int index = 0; index < delimiters.length; index++) {
delimiterHashSet.add(Character.codePointAt(delimiters, index));
}
return delimiterHashSet;
}
}