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/******************************************************************************* |
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* Copyright (c) 2006 IBM Corporation and others. |
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* All rights reserved. This program and the accompanying materials |
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* are made available under the terms of the Common Public License v1.0 |
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* which accompanies this distribution, and is available at |
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* http://www.eclipse.org/legal/cpl-v10.html |
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* |
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* Contributors: |
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* Sebastian Davids <sdavids@gmx.de> - initial API and implementation |
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*******************************************************************************/ |
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package org.eclipse.ui.internal.texteditor; |
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|
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import java.util.StringTokenizer; |
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|
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/** |
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* Helper class to provide String manipulation functions not available in |
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* standard JDK. |
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* |
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* @since 3.3 |
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*/ |
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public class Strings { |
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|
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private Strings() { |
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// Do not instantiate |
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} |
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|
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/** |
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* Capitalizes the given String. |
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* <p> |
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* Since case mappings are not always 1:1 char mappings, the resulting |
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* String may be a different length than the String input. |
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* </p> |
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* <p> |
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* Rules: |
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* </p> |
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* <ul> |
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* <li>the first character will be converted to upper case</li> |
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* <li>each letter directly after a whitespace will be converted to upper |
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* case</li> |
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* </ul> |
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* <p> |
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* Examples: |
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* </p> |
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* |
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* <pre> |
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* Strings.capitalize(null) = null |
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* Strings.capitalize("to be capitalized") = "To Be Capitalized" |
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* Strings.capitalize("§") = "SS" |
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* Strings.capitalize("a\tba") = "A\tBa" |
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* </pre> |
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* |
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* @param input |
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* the String to be capitalized, may be null |
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* @return the capitalized String or <code>null</code> if null String |
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* input |
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* @see java.lang.String#toUpperCase() |
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*/ |
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public static String capitalize(String input) { |
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if (input == null) |
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return null; |
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|
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int len = input.length(); |
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|
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if (len == 0) |
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return input; |
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|
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if (len == 1) |
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return input.toUpperCase(); |
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|
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StringTokenizer st = new StringTokenizer(input, " \t\n\r\f", true); //$NON-NLS-1$ |
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|
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// common case has no 1:M mappings so initialize buffer w/ |
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// length of original String to avoid resizing |
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StringBuffer result = new StringBuffer(input.length()); |
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|
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while (st.hasMoreTokens()) |
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appendCapitalized(result, st.nextToken()); |
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|
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return result.toString(); |
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} |
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|
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/** |
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* Converts the given String to constant case. |
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* <p> |
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* Since case mappings are not always 1:1 char mappings, the resulting |
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* String may be a different length than the String input. |
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* </p> |
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* <p> |
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* Rules: |
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* </p> |
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* <ul> |
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* <li>all letters will be converted to upper case</li> |
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* <li>each upper case letter in the input String will be prefixed by an _ |
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* in the result</li> |
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* <li>if the first character of the input String is an upper case letter |
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* then it wil not be prefixed by _ in the result</li> |
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* </ul> |
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* <p> |
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* Examples: |
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* </p> |
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* |
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* <pre> |
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* Strings.constantCase(null) = null |
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* Strings.constantCase("toConstantCase") = "TO_CONSTANT_CASE" |
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* Strings.constantCase("NoLeadingUnderscore") = "NO_LEADING_UNDERSCORE" |
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* Strings.constantCase("__someExtra__Underscores_") = "__SOME_EXTRA___UNDERSCORES_" |
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* </pre> |
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* |
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* @param input |
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* the String to be converted to constant case, may be null |
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* @return the constant case String or <code>null</code> if null String |
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* input |
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*/ |
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public static String constantCase(String input) { |
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if (input == null) |
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return null; |
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|
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int len = input.length(); |
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|
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if (len == 0) |
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return input; |
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|
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if (len == 1) |
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return input.toUpperCase(); |
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|
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// it is likely that the result is longer than the input; |
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// nethertheless do not set a larger initial size and depend on |
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// StringBuffer's resize strategy |
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StringBuffer buffer = new StringBuffer(input.length()); |
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|
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// toUpperCase on an entire String is more performant than |
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// several String.valueOf(c).toUpperCase() calls in a loop; |
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// so we first just copy and insert _'s |
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|
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// first letter should not be prefixed by _ |
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buffer.append(input.charAt(0)); |
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|
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// now prefix the remaining |
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for (int i = 1; i < len; i++) { |
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char c = input.charAt(i); |
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if (Character.isUpperCase(c)) |
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buffer.append('_'); |
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buffer.append(c); |
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} |
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|
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// now convert to uppercase |
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return buffer.toString().toUpperCase(); |
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} |
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|
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/** |
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* Inverts the case of the given String's letters. |
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* <p> |
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* Since case mappings are not always 1:1 char mappings, the resulting |
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* String may be a different length than the String input. |
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* </p> |
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* <p> |
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* This operation is not symmetric; |
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* <code>Strings.invertCase(Strings.invertCase(input))</code> might not be |
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* equal to <code>input</code>. |
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* </p> |
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* <p> |
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* Rules: |
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* </p> |
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* <ul> |
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* <li>each lower case letter will be converted to upper case</li> |
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* <li>each upper case letter will be converted to lower case</li> |
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* </ul> |
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* <p> |
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* Examples: |
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* </p> |
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* |
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* <pre> |
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* Strings.invertCase(null) = null |
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* Strings.invertCase("To Be Inverted") = "tO bE iNVERTED" |
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* Strings.invertCase("tO bE iNVERTED") = "To Be Inverted" |
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* Strings.invertCase("Maße") = "mASSE" |
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* Strings.invertCase("mASSE") = "Masse" |
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* Strings.invertCase("StringsTest") = "sTRINGStEST" |
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* </pre> |
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* |
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* @param input |
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* the String to be inverted, may be null |
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* @return the inverted String or <code>null</code> if null String input |
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* @see java.lang.String#toLowerCase() |
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* @see java.lang.String#toUpperCase() |
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* @see java.lang.Character#isLetter(char) |
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*/ |
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public static String invertCase(String input) { |
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if (input == null) |
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return null; |
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|
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int len = input.length(); |
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|
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if (len == 0) |
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return input; |
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|
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int i; |
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char c; |
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|
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// skip to first lower case letter |
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for (i = 0; i < len; i++) { |
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c = input.charAt(i); |
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if (Character.isLetter(c) && Character.isLowerCase(c)) |
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break; |
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} |
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// only upper case letters in String? |
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if (i == len) |
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return input.toLowerCase(); |
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// common case has no 1:M mappings so initialize buffer w/ |
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// length of original String to avoid resizing |
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StringBuffer result = new StringBuffer(len); |
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|
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// append upper case letters before first lower case letter |
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result.append(input.substring(0, i).toLowerCase()); |
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|
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// convert the remaining characters |
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for (; i < len; i++) { |
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c = input.charAt(i); |
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if (Character.isLetter(c)) { |
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// String.toUpper/Lower insure 1:M mappings |
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String letter = String.valueOf(c); |
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if (Character.isLowerCase(c)) |
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result.append(letter.toUpperCase()); |
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else |
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result.append(letter.toLowerCase()); |
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} else |
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result.append(c); |
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} |
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return result.toString(); |
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} |
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|
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/** |
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* Converts the given String to lower camel case. |
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* <p> |
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* Since case mappings are not always 1:1 char mappings, the resulting |
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* String may be a different length than the String input. |
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* </p> |
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* <p> |
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* Rules: |
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* </p> |
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* <ul> |
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* <li>the first letter will be converted to lower case</li> |
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* <li>the character _ will be removed unless it is followed by another _ |
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* or if it is a trailing _</li> |
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* <li>a letter following an _ will be converted to upper case</li> |
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* <li>all other letters will be in converted to lower case</li> |
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* </ul> |
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* <p> |
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* Examples: |
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* </p> |
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* |
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* <pre> |
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* Strings.lowerCamelCase(null) = null |
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* Strings.lowerCamelCase("TO_LOWER_CAMEL_CASE") = "toLowerCamelCase" |
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* Strings.lowerCamelCase("_Leading") = "leading" |
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* Strings.lowerCamelCase("__someExtra__underscores_") = "_Someextra_Underscores_" |
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* </pre> |
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* |
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* @param input |
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* the String to be converted to lower camel case, may be null |
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* @return the lower camel case String or <code>null</code> if null String |
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* input |
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*/ |
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public static String lowerCamelCase(String input) { |
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return internalCamelCase(input, false); |
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} |
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|
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/** |
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* Converts the given String to upper camel case. |
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* <p> |
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* Since case mappings are not always 1:1 char mappings, the resulting |
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* String may be a different length than the String input. |
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* </p> |
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* <p> |
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* Rules: |
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* </p> |
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* <ul> |
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* <li>the character _ will be removed unless it is followed by another _ |
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* or if it is a trailing _</li> |
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* <li>a letter following an _ will be converted to upper case</li> |
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* <li>all other letters will be in converted to lower case</li> |
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* </ul> |
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* <p> |
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* Examples: |
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* </p> |
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* |
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* <pre> |
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* Strings.upperCamelCase(null) = null |
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* Strings.upperCamelCase("TO_UPPER_CAMEL_CASE") = "ToUpperCamelCase" |
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* Strings.upperCamelCase("_leading") = "Leading" |
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* Strings.upperCamelCase("__someExtra__underscores_") = "_Someextra_Underscores_" |
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* </pre> |
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* |
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* @param input |
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* the String to be converted to upper camel case, may be null |
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* @return the upper camel case String or <code>null</code> if null String |
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* input |
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*/ |
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public static String upperCamelCase(String input) { |
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return internalCamelCase(input, true); |
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} |
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|
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/** |
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* Converts the given String to upper or lower camel case. |
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* |
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* @param input |
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* the String to be converted, may be null |
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* @param toUpper |
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* <code>true</code> if the input should be converted to upper |
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* camel case, <code>false</code> otherwise |
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* @return the converted String or <code>null</code> if null String input |
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*/ |
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private static String internalCamelCase(String input, boolean toUpper) { |
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if (input == null) |
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return null; |
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|
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if (input.length() == 0) |
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return input; |
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|
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// the result mainly consists of lower case letters; |
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// toLowerCase on the entire String is more performant than |
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// several String.valueOf(c).toLowerCase() calls in the loop below |
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String lower = input.toLowerCase(); |
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int len = lower.length(); |
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StringBuffer buffer = new StringBuffer(len); |
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for (int i = 0; i < len; i++) { |
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char c = lower.charAt(i); |
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if (c == '_') { |
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int j = i + 1; |
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for (; j < len; j++) { |
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c = lower.charAt(j); |
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if (c == '_') { |
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// keep additional _'s |
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buffer.append('_'); |
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} else { |
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if (toUpper || j > 1) { |
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// String.toUpper insures 1:M mappings |
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buffer.append(String.valueOf(c).toUpperCase()); |
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} else { |
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// keep result's first character in lower case |
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buffer.append(c); |
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} |
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break; |
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} |
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} |
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if (j == len) { |
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// keep trailing _ |
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buffer.append('_'); |
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} |
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i = j; |
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} else { |
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// letters are lower case already so just append |
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buffer.append(lower.charAt(i)); |
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} |
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} |
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if (toUpper) { |
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buffer |
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.replace(0, 1, String.valueOf(buffer.charAt(0)) |
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.toUpperCase()); |
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} |
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return buffer.toString(); |
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} |
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|
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/** |
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* Appends the given String to the buffer; the first character of the String |
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* will be appended in upper case if it is a letter. |
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* |
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* @param buffer |
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* the <code>StringBuffer</code> the capitalized input String |
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* will be appended to |
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* @param input |
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* the String to be capitalized |
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*/ |
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private static void appendCapitalized(StringBuffer buffer, String input) { |
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char firstChar = input.charAt(0); |
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|
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if (!Character.isLetter(firstChar)) { |
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buffer.append(input); |
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return; |
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} |
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|
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// capitalize first char of token |
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// String.toUpper insures 1:M mappings |
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buffer.append(String.valueOf(firstChar).toUpperCase()); |
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|
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int len = input.length(); |
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|
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// append remaining chars of token |
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if (len > 1) |
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buffer.append(input.substring(1, len)); |
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} |
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} |
