Java tutorial
/* * Copyright (C) 2009-2010, Google Inc. * and other copyright owners as documented in the project's IP log. * * This program and the accompanying materials are made available * under the terms of the Eclipse Distribution License v1.0 which * accompanies this distribution, is reproduced below, and is * available at http://www.eclipse.org/org/documents/edl-v10.php * * All rights reserved. * * Redistribution and use in source and binary forms, with or * without modification, are permitted provided that the following * conditions are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * - Neither the name of the Eclipse Foundation, Inc. nor the * names of its contributors may be used to endorse or promote * products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package org.eclipse.jgit.util; import java.text.MessageFormat; import java.util.Collection; import org.eclipse.jgit.internal.JGitText; /** * Miscellaneous string comparison utility methods. */ public final class StringUtils { private static final char[] LC; static { LC = new char['Z' + 1]; for (char c = 0; c < LC.length; c++) LC[c] = c; for (char c = 'A'; c <= 'Z'; c++) LC[c] = (char) ('a' + (c - 'A')); } /** * Convert the input to lowercase. * <p> * This method does not honor the JVM locale, but instead always behaves as * though it is in the US-ASCII locale. Only characters in the range 'A' * through 'Z' are converted. All other characters are left as-is, even if * they otherwise would have a lowercase character equivalent. * * @param c * the input character. * @return lowercase version of the input. */ public static char toLowerCase(char c) { return c <= 'Z' ? LC[c] : c; } /** * Convert the input string to lower case, according to the "C" locale. * <p> * This method does not honor the JVM locale, but instead always behaves as * though it is in the US-ASCII locale. Only characters in the range 'A' * through 'Z' are converted, all other characters are left as-is, even if * they otherwise would have a lowercase character equivalent. * * @param in * the input string. Must not be null. * @return a copy of the input string, after converting characters in the * range 'A'..'Z' to 'a'..'z'. */ public static String toLowerCase(String in) { final StringBuilder r = new StringBuilder(in.length()); for (int i = 0; i < in.length(); i++) r.append(toLowerCase(in.charAt(i))); return r.toString(); } /** * Borrowed from commons-lang <code>StringUtils.capitalize()</code> method. * * <p> * Capitalizes a String changing the first letter to title case as per * {@link java.lang.Character#toTitleCase(char)}. No other letters are * changed. * </p> * <p> * A <code>null</code> input String returns <code>null</code>. * </p> * * @param str * the String to capitalize, may be null * @return the capitalized String, <code>null</code> if null String input * @since 4.0 */ public static String capitalize(String str) { int strLen; if (str == null || (strLen = str.length()) == 0) { return str; } return new StringBuilder(strLen).append(Character.toTitleCase(str.charAt(0))).append(str.substring(1)) .toString(); } /** * Test if two strings are equal, ignoring case. * <p> * This method does not honor the JVM locale, but instead always behaves as * though it is in the US-ASCII locale. * * @param a * first string to compare. * @param b * second string to compare. * @return true if a equals b */ public static boolean equalsIgnoreCase(String a, String b) { if (References.isSameObject(a, b)) { return true; } if (a.length() != b.length()) return false; for (int i = 0; i < a.length(); i++) { if (toLowerCase(a.charAt(i)) != toLowerCase(b.charAt(i))) return false; } return true; } /** * Compare two strings, ignoring case. * <p> * This method does not honor the JVM locale, but instead always behaves as * though it is in the US-ASCII locale. * * @param a * first string to compare. * @param b * second string to compare. * @since 2.0 * @return an int. */ public static int compareIgnoreCase(String a, String b) { for (int i = 0; i < a.length() && i < b.length(); i++) { int d = toLowerCase(a.charAt(i)) - toLowerCase(b.charAt(i)); if (d != 0) return d; } return a.length() - b.length(); } /** * Compare two strings, honoring case. * <p> * This method does not honor the JVM locale, but instead always behaves as * though it is in the US-ASCII locale. * * @param a * first string to compare. * @param b * second string to compare. * @since 2.0 * @return an int. */ public static int compareWithCase(String a, String b) { for (int i = 0; i < a.length() && i < b.length(); i++) { int d = a.charAt(i) - b.charAt(i); if (d != 0) return d; } return a.length() - b.length(); } /** * Parse a string as a standard Git boolean value. See * {@link #toBooleanOrNull(String)}. * * @param stringValue * the string to parse. * @return the boolean interpretation of {@code value}. * @throws java.lang.IllegalArgumentException * if {@code value} is not recognized as one of the standard * boolean names. */ public static boolean toBoolean(String stringValue) { if (stringValue == null) throw new NullPointerException(JGitText.get().expectedBooleanStringValue); final Boolean bool = toBooleanOrNull(stringValue); if (bool == null) throw new IllegalArgumentException(MessageFormat.format(JGitText.get().notABoolean, stringValue)); return bool.booleanValue(); } /** * Parse a string as a standard Git boolean value. * <p> * The terms {@code yes}, {@code true}, {@code 1}, {@code on} can all be * used to mean {@code true}. * <p> * The terms {@code no}, {@code false}, {@code 0}, {@code off} can all be * used to mean {@code false}. * <p> * Comparisons ignore case, via {@link #equalsIgnoreCase(String, String)}. * * @param stringValue * the string to parse. * @return the boolean interpretation of {@code value} or null in case the * string does not represent a boolean value */ public static Boolean toBooleanOrNull(String stringValue) { if (stringValue == null) return null; if (equalsIgnoreCase("yes", stringValue) //$NON-NLS-1$ || equalsIgnoreCase("true", stringValue) //$NON-NLS-1$ || equalsIgnoreCase("1", stringValue) //$NON-NLS-1$ || equalsIgnoreCase("on", stringValue)) //$NON-NLS-1$ return Boolean.TRUE; else if (equalsIgnoreCase("no", stringValue) //$NON-NLS-1$ || equalsIgnoreCase("false", stringValue) //$NON-NLS-1$ || equalsIgnoreCase("0", stringValue) //$NON-NLS-1$ || equalsIgnoreCase("off", stringValue)) //$NON-NLS-1$ return Boolean.FALSE; else return null; } /** * Join a collection of Strings together using the specified separator. * * @param parts * Strings to join * @param separator * used to join * @return a String with all the joined parts */ public static String join(Collection<String> parts, String separator) { return StringUtils.join(parts, separator, separator); } /** * Join a collection of Strings together using the specified separator and a * lastSeparator which is used for joining the second last and the last * part. * * @param parts * Strings to join * @param separator * separator used to join all but the two last elements * @param lastSeparator * separator to use for joining the last two elements * @return a String with all the joined parts */ public static String join(Collection<String> parts, String separator, String lastSeparator) { StringBuilder sb = new StringBuilder(); int i = 0; int lastIndex = parts.size() - 1; for (String part : parts) { sb.append(part); if (i == lastIndex - 1) { sb.append(lastSeparator); } else if (i != lastIndex) { sb.append(separator); } i++; } return sb.toString(); } private StringUtils() { // Do not create instances } /** * Test if a string is empty or null. * * @param stringValue * the string to check * @return <code>true</code> if the string is <code>null</code> or empty */ public static boolean isEmptyOrNull(String stringValue) { return stringValue == null || stringValue.length() == 0; } /** * Replace CRLF, CR or LF with a single space. * * @param in * A string with line breaks * @return in without line breaks * @since 3.1 */ public static String replaceLineBreaksWithSpace(String in) { char[] buf = new char[in.length()]; int o = 0; for (int i = 0; i < buf.length; ++i) { char ch = in.charAt(i); switch (ch) { case '\r': if (i + 1 < buf.length && in.charAt(i + 1) == '\n') { buf[o++] = ' '; ++i; } else buf[o++] = ' '; break; case '\n': buf[o++] = ' '; break; default: buf[o++] = ch; break; } } return new String(buf, 0, o); } }