Java tutorial
/** * 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 * <p> * http://www.apache.org/licenses/LICENSE-2.0 * <p> * 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 com.buaa.cfs.utils; import com.buaa.cfs.fs.Path; import com.google.common.base.Preconditions; import com.google.common.net.InetAddresses; import org.apache.commons.lang.SystemUtils; import java.io.PrintWriter; import java.io.StringWriter; import java.net.URI; import java.net.URISyntaxException; import java.text.DateFormat; import java.util.*; import java.util.regex.Matcher; import java.util.regex.Pattern; /** * General string utils */ public class StringUtils { /** * Priority of the StringUtils shutdown hook. */ public static final int SHUTDOWN_HOOK_PRIORITY = 0; /** * Shell environment variables: $ followed by one letter or _ followed by multiple letters, numbers, or underscores. * The group captures the environment variable name without the leading $. */ public static final Pattern SHELL_ENV_VAR_PATTERN = Pattern.compile("\\$([A-Za-z_]{1}[A-Za-z0-9_]*)"); /** * Windows environment variables: surrounded by %. The group captures the environment variable name without the * leading and trailing %. */ public static final Pattern WIN_ENV_VAR_PATTERN = Pattern.compile("%(.*?)%"); /** * Regular expression that matches and captures environment variable names according to platform-specific rules. */ public static final Pattern ENV_VAR_PATTERN = Shell.WINDOWS ? WIN_ENV_VAR_PATTERN : SHELL_ENV_VAR_PATTERN; /** * Make a string representation of the exception. * * @param e The exception to stringify * * @return A string with exception name and call stack. */ public static String stringifyException(Throwable e) { StringWriter stm = new StringWriter(); PrintWriter wrt = new PrintWriter(stm); e.printStackTrace(wrt); wrt.close(); return stm.toString(); } /** * Given a full hostname, return the word upto the first dot. * * @param fullHostname the full hostname * * @return the hostname to the first dot */ public static String simpleHostname(String fullHostname) { if (InetAddresses.isInetAddress(fullHostname)) { return fullHostname; } int offset = fullHostname.indexOf('.'); if (offset != -1) { return fullHostname.substring(0, offset); } return fullHostname; } /** * Given an integer, return a string that is in an approximate, but human readable format. * * @param number the number to format * * @return a human readable form of the integer * * @deprecated use {@link TraditionalBinaryPrefix#long2String(long, String, int)}. */ @Deprecated public static String humanReadableInt(long number) { return TraditionalBinaryPrefix.long2String(number, "", 1); } /** The same as String.format(Locale.ENGLISH, format, objects). */ public static String format(final String format, final Object... objects) { return String.format(Locale.ENGLISH, format, objects); } /** * Format a percentage for presentation to the user. * * @param fraction the percentage as a fraction, e.g. 0.1 = 10% * @param decimalPlaces the number of decimal places * * @return a string representation of the percentage */ public static String formatPercent(double fraction, int decimalPlaces) { return format("%." + decimalPlaces + "f%%", fraction * 100); } /** * Given an array of strings, return a comma-separated list of its elements. * * @param strs Array of strings * * @return Empty string if strs.length is 0, comma separated list of strings otherwise */ public static String arrayToString(String[] strs) { if (strs.length == 0) { return ""; } StringBuilder sbuf = new StringBuilder(); sbuf.append(strs[0]); for (int idx = 1; idx < strs.length; idx++) { sbuf.append(","); sbuf.append(strs[idx]); } return sbuf.toString(); } /** * Given an array of bytes it will convert the bytes to a hex string representation of the bytes * * @param bytes * @param start start index, inclusively * @param end end index, exclusively * * @return hex string representation of the byte array */ public static String byteToHexString(byte[] bytes, int start, int end) { if (bytes == null) { throw new IllegalArgumentException("bytes == null"); } StringBuilder s = new StringBuilder(); for (int i = start; i < end; i++) { s.append(format("%02x", bytes[i])); } return s.toString(); } /** Same as byteToHexString(bytes, 0, bytes.length). */ public static String byteToHexString(byte bytes[]) { return byteToHexString(bytes, 0, bytes.length); } /** * Given a hexstring this will return the byte array corresponding to the string * * @param hex the hex String array * * @return a byte array that is a hex string representation of the given string. The size of the byte array is * therefore hex.length/2 */ public static byte[] hexStringToByte(String hex) { byte[] bts = new byte[hex.length() / 2]; for (int i = 0; i < bts.length; i++) { bts[i] = (byte) Integer.parseInt(hex.substring(2 * i, 2 * i + 2), 16); } return bts; } /** * @param uris */ public static String uriToString(URI[] uris) { if (uris == null) { return null; } StringBuilder ret = new StringBuilder(uris[0].toString()); for (int i = 1; i < uris.length; i++) { ret.append(","); ret.append(uris[i].toString()); } return ret.toString(); } /** * @param str The string array to be parsed into an URI array. * * @return <tt>null</tt> if str is <tt>null</tt>, else the URI array equivalent to str. * * @throws IllegalArgumentException If any string in str violates RFC 2396. */ public static URI[] stringToURI(String[] str) { if (str == null) return null; URI[] uris = new URI[str.length]; for (int i = 0; i < str.length; i++) { try { uris[i] = new URI(str[i]); } catch (URISyntaxException ur) { throw new IllegalArgumentException("Failed to create uri for " + str[i], ur); } } return uris; } /** * @param str */ public static Path[] stringToPath(String[] str) { if (str == null) { return null; } Path[] p = new Path[str.length]; for (int i = 0; i < str.length; i++) { p[i] = new Path(str[i]); } return p; } /** * Given a finish and start time in long milliseconds, returns a String in the format Xhrs, Ymins, Z sec, for the * time difference between two times. If finish time comes before start time then negative valeus of X, Y and Z wil * return. * * @param finishTime finish time * @param startTime start time */ public static String formatTimeDiff(long finishTime, long startTime) { long timeDiff = finishTime - startTime; return formatTime(timeDiff); } /** * Given the time in long milliseconds, returns a String in the format Xhrs, Ymins, Z sec. * * @param timeDiff The time difference to format */ public static String formatTime(long timeDiff) { StringBuilder buf = new StringBuilder(); long hours = timeDiff / (60 * 60 * 1000); long rem = (timeDiff % (60 * 60 * 1000)); long minutes = rem / (60 * 1000); rem = rem % (60 * 1000); long seconds = rem / 1000; if (hours != 0) { buf.append(hours); buf.append("hrs, "); } if (minutes != 0) { buf.append(minutes); buf.append("mins, "); } // return "0sec if no difference buf.append(seconds); buf.append("sec"); return buf.toString(); } /** * Formats time in ms and appends difference (finishTime - startTime) as returned by formatTimeDiff(). If finish * time is 0, empty string is returned, if start time is 0 then difference is not appended to return value. * * @param dateFormat date format to use * @param finishTime fnish time * @param startTime start time * * @return formatted value. */ public static String getFormattedTimeWithDiff(DateFormat dateFormat, long finishTime, long startTime) { StringBuilder buf = new StringBuilder(); if (0 != finishTime) { buf.append(dateFormat.format(new Date(finishTime))); if (0 != startTime) { buf.append(" (" + formatTimeDiff(finishTime, startTime) + ")"); } } return buf.toString(); } /** * Returns an arraylist of strings. * * @param str the comma seperated string values * * @return the arraylist of the comma seperated string values */ public static String[] getStrings(String str) { Collection<String> values = getStringCollection(str); if (values.size() == 0) { return null; } return values.toArray(new String[values.size()]); } /** * Returns a collection of strings. * * @param str comma seperated string values * * @return an <code>ArrayList</code> of string values */ public static Collection<String> getStringCollection(String str) { String delim = ","; return getStringCollection(str, delim); } /** * Returns a collection of strings. * * @param str String to parse * @param delim delimiter to separate the values * * @return Collection of parsed elements. */ public static Collection<String> getStringCollection(String str, String delim) { List<String> values = new ArrayList<String>(); if (str == null) return values; StringTokenizer tokenizer = new StringTokenizer(str, delim); while (tokenizer.hasMoreTokens()) { values.add(tokenizer.nextToken()); } return values; } /** * Splits a comma separated value <code>String</code>, trimming leading and trailing whitespace on each value. * Duplicate and empty values are removed. * * @param str a comma separated <String> with values * * @return a <code>Collection</code> of <code>String</code> values */ public static Collection<String> getTrimmedStringCollection(String str) { Set<String> set = new LinkedHashSet<String>(Arrays.asList(getTrimmedStrings(str))); set.remove(""); return set; } /** * Splits a comma separated value <code>String</code>, trimming leading and trailing whitespace on each value. * * @param str a comma separated <String> with values * * @return an array of <code>String</code> values */ public static String[] getTrimmedStrings(String str) { if (null == str || str.trim().isEmpty()) { return emptyStringArray; } return str.trim().split("\\s*,\\s*"); } /** * Trims all the strings in a Collection<String> and returns a Set<String>. * * @param strings * * @return */ public static Set<String> getTrimmedStrings(Collection<String> strings) { Set<String> trimmedStrings = new HashSet<String>(); for (String string : strings) { trimmedStrings.add(string.trim()); } return trimmedStrings; } final public static String[] emptyStringArray = {}; final public static char COMMA = ','; final public static String COMMA_STR = ","; final public static char ESCAPE_CHAR = '\\'; /** * Split a string using the default separator * * @param str a string that may have escaped separator * * @return an array of strings */ public static String[] split(String str) { return split(str, ESCAPE_CHAR, COMMA); } /** * Split a string using the given separator * * @param str a string that may have escaped separator * @param escapeChar a char that be used to escape the separator * @param separator a separator char * * @return an array of strings */ public static String[] split(String str, char escapeChar, char separator) { if (str == null) { return null; } ArrayList<String> strList = new ArrayList<String>(); StringBuilder split = new StringBuilder(); int index = 0; while ((index = findNext(str, separator, escapeChar, index, split)) >= 0) { ++index; // move over the separator for next search strList.add(split.toString()); split.setLength(0); // reset the buffer } strList.add(split.toString()); // remove trailing empty split(s) int last = strList.size(); // last split while (--last >= 0 && "".equals(strList.get(last))) { strList.remove(last); } return strList.toArray(new String[strList.size()]); } /** * Split a string using the given separator, with no escaping performed. * * @param str a string to be split. Note that this may not be null. * @param separator a separator char * * @return an array of strings */ public static String[] split(String str, char separator) { // String.split returns a single empty result for splitting the empty // string. if (str.isEmpty()) { return new String[] { "" }; } ArrayList<String> strList = new ArrayList<String>(); int startIndex = 0; int nextIndex = 0; while ((nextIndex = str.indexOf(separator, startIndex)) != -1) { strList.add(str.substring(startIndex, nextIndex)); startIndex = nextIndex + 1; } strList.add(str.substring(startIndex)); // remove trailing empty split(s) int last = strList.size(); // last split while (--last >= 0 && "".equals(strList.get(last))) { strList.remove(last); } return strList.toArray(new String[strList.size()]); } /** * Finds the first occurrence of the separator character ignoring the escaped separators starting from the index. * Note the substring between the index and the position of the separator is passed. * * @param str the source string * @param separator the character to find * @param escapeChar character used to escape * @param start from where to search * @param split used to pass back the extracted string */ public static int findNext(String str, char separator, char escapeChar, int start, StringBuilder split) { int numPreEscapes = 0; for (int i = start; i < str.length(); i++) { char curChar = str.charAt(i); if (numPreEscapes == 0 && curChar == separator) { // separator return i; } else { split.append(curChar); numPreEscapes = (curChar == escapeChar) ? (++numPreEscapes) % 2 : 0; } } return -1; } /** * Escape commas in the string using the default escape char * * @param str a string * * @return an escaped string */ public static String escapeString(String str) { return escapeString(str, ESCAPE_CHAR, COMMA); } /** * Escape <code>charToEscape</code> in the string with the escape char <code>escapeChar</code> * * @param str string * @param escapeChar escape char * @param charToEscape the char to be escaped * * @return an escaped string */ public static String escapeString(String str, char escapeChar, char charToEscape) { return escapeString(str, escapeChar, new char[] { charToEscape }); } // check if the character array has the character private static boolean hasChar(char[] chars, char character) { for (char target : chars) { if (character == target) { return true; } } return false; } /** * @param charsToEscape array of characters to be escaped */ public static String escapeString(String str, char escapeChar, char[] charsToEscape) { if (str == null) { return null; } StringBuilder result = new StringBuilder(); for (int i = 0; i < str.length(); i++) { char curChar = str.charAt(i); if (curChar == escapeChar || hasChar(charsToEscape, curChar)) { // special char result.append(escapeChar); } result.append(curChar); } return result.toString(); } /** * Unescape commas in the string using the default escape char * * @param str a string * * @return an unescaped string */ public static String unEscapeString(String str) { return unEscapeString(str, ESCAPE_CHAR, COMMA); } /** * Unescape <code>charToEscape</code> in the string with the escape char <code>escapeChar</code> * * @param str string * @param escapeChar escape char * @param charToEscape the escaped char * * @return an unescaped string */ public static String unEscapeString(String str, char escapeChar, char charToEscape) { return unEscapeString(str, escapeChar, new char[] { charToEscape }); } /** * @param charsToEscape array of characters to unescape */ public static String unEscapeString(String str, char escapeChar, char[] charsToEscape) { if (str == null) { return null; } StringBuilder result = new StringBuilder(str.length()); boolean hasPreEscape = false; for (int i = 0; i < str.length(); i++) { char curChar = str.charAt(i); if (hasPreEscape) { if (curChar != escapeChar && !hasChar(charsToEscape, curChar)) { // no special char throw new IllegalArgumentException( "Illegal escaped string " + str + " unescaped " + escapeChar + " at " + (i - 1)); } // otherwise discard the escape char result.append(curChar); hasPreEscape = false; } else { if (hasChar(charsToEscape, curChar)) { throw new IllegalArgumentException( "Illegal escaped string " + str + " unescaped " + curChar + " at " + i); } else if (curChar == escapeChar) { hasPreEscape = true; } else { result.append(curChar); } } } if (hasPreEscape) { throw new IllegalArgumentException( "Illegal escaped string " + str + ", not expecting " + escapeChar + " in the end."); } return result.toString(); } /** * Return a message for logging. * * @param prefix prefix keyword for the message * @param msg content of the message * * @return a message for logging */ private static String toStartupShutdownString(String prefix, String[] msg) { StringBuilder b = new StringBuilder(prefix); b.append("\n/************************************************************"); for (String s : msg) b.append("\n" + prefix + s); b.append("\n************************************************************/"); return b.toString(); } /** * Print a log message for starting up and shutting down * * @param clazz the class of the server * @param args arguments * @param LOG the target log object */ public static void startupShutdownMessage(Class<?> clazz, String[] args, final org.apache.commons.logging.Log LOG) { startupShutdownMessage(clazz, args, LogAdapter.create(LOG)); } /** * Print a log message for starting up and shutting down * * @param clazz the class of the server * @param args arguments * @param LOG the target log object */ public static void startupShutdownMessage(Class<?> clazz, String[] args, final org.slf4j.Logger LOG) { startupShutdownMessage(clazz, args, LogAdapter.create(LOG)); } static void startupShutdownMessage(Class<?> clazz, String[] args, final LogAdapter LOG) { final String hostname = NetUtils.getHostname(); final String classname = clazz.getSimpleName(); LOG.info(toStartupShutdownString("STARTUP_MSG: ", new String[] { "Starting " + classname, " host = " + hostname, " args = " + Arrays.asList(args), " version = " + VersionInfo.getVersion(), " classpath = " + System.getProperty("java.class.path"), " build = " + VersionInfo.getUrl() + " -r " + VersionInfo.getRevision() + "; compiled by '" + VersionInfo.getUser() + "' on " + VersionInfo.getDate(), " java = " + System.getProperty("java.version") })); if (SystemUtils.IS_OS_UNIX) { try { SignalLogger.INSTANCE.register(LOG); } catch (Throwable t) { LOG.warn("failed to register any UNIX signal loggers: ", t); } } ShutdownHookManager.get().addShutdownHook(new Runnable() { @Override public void run() { LOG.info(toStartupShutdownString("SHUTDOWN_MSG: ", new String[] { "Shutting down " + classname + " at " + hostname })); } }, SHUTDOWN_HOOK_PRIORITY); } /** * The traditional binary prefixes, kilo, mega, ..., exa, which can be represented by a 64-bit integer. * TraditionalBinaryPrefix symbol are case insensitive. */ public static enum TraditionalBinaryPrefix { KILO(10), MEGA(KILO.bitShift + 10), GIGA(MEGA.bitShift + 10), TERA(GIGA.bitShift + 10), PETA( TERA.bitShift + 10), EXA(PETA.bitShift + 10); public final long value; public final char symbol; public final int bitShift; public final long bitMask; private TraditionalBinaryPrefix(int bitShift) { this.bitShift = bitShift; this.value = 1L << bitShift; this.bitMask = this.value - 1L; this.symbol = toString().charAt(0); } /** * @return The TraditionalBinaryPrefix object corresponding to the symbol. */ public static TraditionalBinaryPrefix valueOf(char symbol) { symbol = Character.toUpperCase(symbol); for (TraditionalBinaryPrefix prefix : TraditionalBinaryPrefix.values()) { if (symbol == prefix.symbol) { return prefix; } } throw new IllegalArgumentException("Unknown symbol '" + symbol + "'"); } /** * Convert a string to long. The input string is first be trimmed and then it is parsed with traditional binary * prefix. * <p> * For example, "-1230k" will be converted to -1230 * 1024 = -1259520; "891g" will be converted to 891 * 1024^3 * = 956703965184; * * @param s input string * * @return a long value represented by the input string. */ public static long string2long(String s) { s = s.trim(); final int lastpos = s.length() - 1; final char lastchar = s.charAt(lastpos); if (Character.isDigit(lastchar)) return Long.parseLong(s); else { long prefix; try { prefix = TraditionalBinaryPrefix.valueOf(lastchar).value; } catch (IllegalArgumentException e) { throw new IllegalArgumentException("Invalid size prefix '" + lastchar + "' in '" + s + "'. Allowed prefixes are k, m, g, t, p, e(case insensitive)"); } long num = Long.parseLong(s.substring(0, lastpos)); if (num > (Long.MAX_VALUE / prefix) || num < (Long.MIN_VALUE / prefix)) { throw new IllegalArgumentException(s + " does not fit in a Long"); } return num * prefix; } } /** * Convert a long integer to a string with traditional binary prefix. * * @param n the value to be converted * @param unit The unit, e.g. "B" for bytes. * @param decimalPlaces The number of decimal places. * * @return a string with traditional binary prefix. */ public static String long2String(long n, String unit, int decimalPlaces) { if (unit == null) { unit = ""; } //take care a special case if (n == Long.MIN_VALUE) { return "-8 " + EXA.symbol + unit; } final StringBuilder b = new StringBuilder(); //take care negative numbers if (n < 0) { b.append('-'); n = -n; } if (n < KILO.value) { //no prefix b.append(n); return (unit.isEmpty() ? b : b.append(" ").append(unit)).toString(); } else { //find traditional binary prefix int i = 0; for (; i < values().length && n >= values()[i].value; i++) ; TraditionalBinaryPrefix prefix = values()[i - 1]; if ((n & prefix.bitMask) == 0) { //exact division b.append(n >> prefix.bitShift); } else { final String format = "%." + decimalPlaces + "f"; String s = format(format, n / (double) prefix.value); //check a special rounding up case if (s.startsWith("1024")) { prefix = values()[i]; s = format(format, n / (double) prefix.value); } b.append(s); } return b.append(' ').append(prefix.symbol).append(unit).toString(); } } } /** * Escapes HTML Special characters present in the string. * * @param string * * @return HTML Escaped String representation */ public static String escapeHTML(String string) { if (string == null) { return null; } StringBuilder sb = new StringBuilder(); boolean lastCharacterWasSpace = false; char[] chars = string.toCharArray(); for (char c : chars) { if (c == ' ') { if (lastCharacterWasSpace) { lastCharacterWasSpace = false; sb.append(" "); } else { lastCharacterWasSpace = true; sb.append(" "); } } else { lastCharacterWasSpace = false; switch (c) { case '<': sb.append("<"); break; case '>': sb.append(">"); break; case '&': sb.append("&"); break; case '"': sb.append("""); break; default: sb.append(c); break; } } } return sb.toString(); } /** * @return a byte description of the given long interger value. */ public static String byteDesc(long len) { return TraditionalBinaryPrefix.long2String(len, "B", 2); } /** @deprecated use StringUtils.format("%.2f", d). */ @Deprecated public static String limitDecimalTo2(double d) { return format("%.2f", d); } /** * Concatenates strings, using a separator. * * @param separator Separator to join with. * @param strings Strings to join. */ public static String join(CharSequence separator, Iterable<?> strings) { Iterator<?> i = strings.iterator(); if (!i.hasNext()) { return ""; } StringBuilder sb = new StringBuilder(i.next().toString()); while (i.hasNext()) { sb.append(separator); sb.append(i.next().toString()); } return sb.toString(); } /** * Concatenates strings, using a separator. * * @param separator to join with * @param strings to join * * @return the joined string */ public static String join(CharSequence separator, String[] strings) { // Ideally we don't have to duplicate the code here if array is iterable. StringBuilder sb = new StringBuilder(); boolean first = true; for (String s : strings) { if (first) { first = false; } else { sb.append(separator); } sb.append(s); } return sb.toString(); } /** * Convert SOME_STUFF to SomeStuff * * @param s input string * * @return camelized string */ public static String camelize(String s) { StringBuilder sb = new StringBuilder(); String[] words = split(StringUtils.toLowerCase(s), ESCAPE_CHAR, '_'); for (String word : words) sb.append(org.apache.commons.lang.StringUtils.capitalize(word)); return sb.toString(); } /** * Matches a template string against a pattern, replaces matched tokens with the supplied replacements, and returns * the result. The regular expression must use a capturing group. The value of the first capturing group is used * to look up the replacement. If no replacement is found for the token, then it is replaced with the empty * string. * <p> * For example, assume template is "%foo%_%bar%_%baz%", pattern is "%(.*?)%", and replacements contains 2 entries, * mapping "foo" to "zoo" and "baz" to "zaz". The result returned would be "zoo__zaz". * * @param template String template to receive replacements * @param pattern Pattern to match for identifying tokens, must use a capturing group * @param replacements Map<String, String> mapping tokens identified by the capturing group to their replacement * values * * @return String template with replacements */ public static String replaceTokens(String template, Pattern pattern, Map<String, String> replacements) { StringBuffer sb = new StringBuffer(); Matcher matcher = pattern.matcher(template); while (matcher.find()) { String replacement = replacements.get(matcher.group(1)); if (replacement == null) { replacement = ""; } matcher.appendReplacement(sb, Matcher.quoteReplacement(replacement)); } matcher.appendTail(sb); return sb.toString(); } /** * Get stack trace for a given thread. */ public static String getStackTrace(Thread t) { final StackTraceElement[] stackTrace = t.getStackTrace(); StringBuilder str = new StringBuilder(); for (StackTraceElement e : stackTrace) { str.append(e.toString() + "\n"); } return str.toString(); } /** * From a list of command-line arguments, remove both an option and the next argument. * * @param name Name of the option to remove. Example: -foo. * @param args List of arguments. * * @return null if the option was not found; the value of the option otherwise. * * @throws IllegalArgumentException if the option's argument is not present */ public static String popOptionWithArgument(String name, List<String> args) throws IllegalArgumentException { String val = null; for (Iterator<String> iter = args.iterator(); iter.hasNext();) { String cur = iter.next(); if (cur.equals("--")) { // stop parsing arguments when you see -- break; } else if (cur.equals(name)) { iter.remove(); if (!iter.hasNext()) { throw new IllegalArgumentException("option " + name + " requires 1 " + "argument."); } val = iter.next(); iter.remove(); break; } } return val; } /** * From a list of command-line arguments, remove an option. * * @param name Name of the option to remove. Example: -foo. * @param args List of arguments. * * @return true if the option was found and removed; false otherwise. */ public static boolean popOption(String name, List<String> args) { for (Iterator<String> iter = args.iterator(); iter.hasNext();) { String cur = iter.next(); if (cur.equals("--")) { // stop parsing arguments when you see -- break; } else if (cur.equals(name)) { iter.remove(); return true; } } return false; } /** * From a list of command-line arguments, return the first non-option argument. Non-option arguments are those * which either come after a double dash (--) or do not start with a dash. * * @param args List of arguments. * * @return The first non-option argument, or null if there were none. */ public static String popFirstNonOption(List<String> args) { for (Iterator<String> iter = args.iterator(); iter.hasNext();) { String cur = iter.next(); if (cur.equals("--")) { if (!iter.hasNext()) { return null; } cur = iter.next(); iter.remove(); return cur; } else if (!cur.startsWith("-")) { iter.remove(); return cur; } } return null; } /** * Converts all of the characters in this String to lower case with Locale.ENGLISH. * * @param str string to be converted * * @return the str, converted to lowercase. */ public static String toLowerCase(String str) { return str.toLowerCase(Locale.ENGLISH); } /** * Converts all of the characters in this String to upper case with Locale.ENGLISH. * * @param str string to be converted * * @return the str, converted to uppercase. */ public static String toUpperCase(String str) { return str.toUpperCase(Locale.ENGLISH); } /** * Compare strings locale-freely by using String#equalsIgnoreCase. * * @param s1 Non-null string to be converted * @param s2 string to be converted * * @return the str, converted to uppercase. */ public static boolean equalsIgnoreCase(String s1, String s2) { Preconditions.checkNotNull(s1); // don't check non-null against s2 to make the semantics same as // s1.equals(s2) return s1.equalsIgnoreCase(s2); } }