net.jawr.web.util.StringUtils Maven / Gradle / Ivy
Show all versions of jawr-core 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
*/
package net.jawr.web.util;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.regex.Pattern;
/**
*
* Utility method for String manipulation.
* The original code is available in commons-lang.
*
* Below are the original authors of StringUtils.
*
* @see java.lang.String
* @author Apache Jakarta Turbine
* @author Jon S. Stevens
* @author Daniel L. Rall
* @author Greg Coladonato
* @author Ed Korthof
* @author Rand McNeely
* @author Stephen Colebourne
* @author Fredrik Westermarck
* @author Holger Krauth
* @author Alexander Day Chaffee
* @author Henning P. Schmiedehausen
* @author Arun Mammen Thomas
* @author Gary Gregory
* @author Phil Steitz
* @author Al Chou
* @author Michael Davey
* @author Reuben Sivan
* @author Chris Hyzer
* @author Scott Johnson
* @since 1.0
* @version $Id: StringUtils.java 635447 2008-03-10 06:27:09Z bayard $
*/
public class StringUtils {
/** The new line separator */
public static final String LINE_SEPARATOR = "\r\n";
//public static final String LINE_SEPARATOR = System.getProperty("line.separator");
/** The string value for line feed */
public static final String STR_LINE_FEED= "\n";
/**
* \u000a linefeed LF ('\n').
*
* @see JLF: Escape Sequences for Character and String
* Literals
* @since 2.2
*/
public static final char LF = '\n';
/**
* \u000d carriage return CR ('\r').
*
* @see JLF: Escape Sequences for Character and String
* Literals
* @since 2.2
*/
public static final char CR = '\r';
/**
* The empty String "".
*
* @since 2.0
*/
public static final String EMPTY = "";
// Empty checks
// -----------------------------------------------------------------------
/**
*
* Checks if a String is empty ("") or null.
*
*
*
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = false
* StringUtils.isEmpty("bob") = false
* StringUtils.isEmpty(" bob ") = false
*
*
*
* NOTE: This method changed in Lang version 2.0. It no longer trims the String. That functionality is available in isBlank().
*
*
* @param str the String to check, may be null
* @return true if the String is empty or null
*/
public static boolean isEmpty(String str) {
return str == null || str.length() == 0;
}
/**
* Checks if a String is not empty ("") and not null.
*
*
* StringUtils.isNotEmpty(null) = false
* StringUtils.isNotEmpty("") = false
* StringUtils.isNotEmpty(" ") = true
* StringUtils.isNotEmpty("bob") = true
* StringUtils.isNotEmpty(" bob ") = true
*
*
* @param str the String to check, may be null
* @return true if the String is not empty and not null
*/
public static boolean isNotEmpty(String str) {
return !StringUtils.isEmpty(str);
}
/**
* Checks if 2 Strings are equals.
* @param cs1 the first string
* @param cs2 the second string
* @return true if the 2 Strings are equals.
*/
public static boolean equals(final String cs1, final String cs2) {
if (cs1 == cs2) {
return true;
}
if (cs1 == null || cs2 == null) {
return false;
}
return cs1.equals(cs2);
}
// Count matches
// -----------------------------------------------------------------------
/**
*
* Counts how many times the substring appears in the larger String.
*
*
*
* A null or empty ("") String input returns 0.
*
*
*
* StringUtils.countMatches(null, *) = 0
* StringUtils.countMatches("", *) = 0
* StringUtils.countMatches("abba", null) = 0
* StringUtils.countMatches("abba", "") = 0
* StringUtils.countMatches("abba", "a") = 2
* StringUtils.countMatches("abba", "ab") = 1
* StringUtils.countMatches("abba", "xxx") = 0
*
*
* @param str the String to check, may be null
* @param sub the substring to count, may be null
* @return the number of occurrences, 0 if either String is null
*/
public static int countMatches(String str, String sub) {
if (isEmpty(str) || isEmpty(sub)) {
return 0;
}
int count = 0;
int idx = 0;
while ((idx = str.indexOf(sub, idx)) != -1) {
count++;
idx += sub.length();
}
return count;
}
// Chopping
// -----------------------------------------------------------------------
/**
*
* Remove the last character from a String.
*
*
*
* If the String ends in \r\n, then remove both of them.
*
*
*
* StringUtils.chop(null) = null
* StringUtils.chop("") = ""
* StringUtils.chop("abc \r") = "abc "
* StringUtils.chop("abc\n") = "abc"
* StringUtils.chop("abc\r\n") = "abc"
* StringUtils.chop("abc") = "ab"
* StringUtils.chop("abc\nabc") = "abc\nab"
* StringUtils.chop("a") = ""
* StringUtils.chop("\r") = ""
* StringUtils.chop("\n") = ""
* StringUtils.chop("\r\n") = ""
*
*
* @param str the String to chop last character from, may be null
* @return String without last character, null if null String input
*/
public static String chop(String str) {
if (str == null) {
return null;
}
int strLen = str.length();
if (strLen < 2) {
return EMPTY;
}
int lastIdx = strLen - 1;
String ret = str.substring(0, lastIdx);
char last = str.charAt(lastIdx);
if (last == LF) {
if (ret.charAt(lastIdx - 1) == CR) {
return ret.substring(0, lastIdx - 1);
}
}
return ret;
}
/**
* Removes separator from the end of
* str if it's there, otherwise leave it alone.
*
* NOTE: This method changed in version 2.0.
* It now more closely matches Perl chomp.
* For the previous behavior, use {@link #substringBeforeLast(String, String)}.
* This method uses {@link String#endsWith(String)}.
*
*
* StringUtils.chomp(null, *) = null
* StringUtils.chomp("", *) = ""
* StringUtils.chomp("foobar", "bar") = "foo"
* StringUtils.chomp("foobar", "baz") = "foobar"
* StringUtils.chomp("foo", "foo") = ""
* StringUtils.chomp("foo ", "foo") = "foo "
* StringUtils.chomp(" foo", "foo") = " "
* StringUtils.chomp("foo", "foooo") = "foo"
* StringUtils.chomp("foo", "") = "foo"
* StringUtils.chomp("foo", null) = "foo"
*
*
* @param str the String to chomp from, may be null
* @param separator separator String, may be null
* @return String without trailing separator, null if null String input
*/
public static String chomp(String str, String separator) {
if (isEmpty(str) || separator == null) {
return str;
}
if (str.endsWith(separator)) {
return str.substring(0, str.length() - separator.length());
}
return str;
}
/**
* Remove a value if and only if the String ends with that value.
*
* @param str the String to chomp from, must not be null
* @param sep the String to chomp, must not be null
* @return String without chomped ending
* @throws NullPointerException if str or sep is null
*/
public static String chompLast(String str, String sep) {
if (str.length() == 0) {
return str;
}
String sub = str.substring(str.length() - sep.length());
if (sep.equals(sub)) {
return str.substring(0, str.length() - sep.length());
}
return str;
}
/**
* Split the String passed in parameter, the trailing empty string are kept.
* @param str the string to split
* @param separator the separator
* @return the splitted string
*/
public static String[] split(String str, String separator){
return Pattern.compile(separator).split(str, -1);
}
/**
* Normalize the line feed of the String. "\r\n" is replaced by "\n"
* @param value the value to normalized
* @return the normalized value
*/
public static String normalizeLineFeed(String value){
return value.replace("\r\n", "\n");
}
/**
* Take a {@code String} that is a delimited list and convert it into a
* {@code String} array.
* A single {@code delimiter} may consist of more than one character,
* but it will still be considered as a single delimiter string, rather
* than as bunch of potential delimiter characters, in contrast to
* {@link #tokenizeToStringArray}.
* @param str the input {@code String}
* @param delimiter the delimiter between elements (this is a single delimiter,
* rather than a bunch individual delimiter characters)
* @return an array of the tokens in the list
* @see #tokenizeToStringArray
*/
public static String[] delimitedListToStringArray(String str, String delimiter) {
return delimitedListToStringArray(str, delimiter, null);
}
/**
* Take a {@code String} that is a delimited list and convert it into
* a {@code String} array.
*
A single {@code delimiter} may consist of more than one character,
* but it will still be considered as a single delimiter string, rather
* than as bunch of potential delimiter characters, in contrast to
* {@link #tokenizeToStringArray}.
* @param str the input {@code String}
* @param delimiter the delimiter between elements (this is a single delimiter,
* rather than a bunch individual delimiter characters)
* @param charsToDelete a set of characters to delete; useful for deleting unwanted
* line breaks: e.g. "\r\n\f" will delete all new lines and line feeds in a {@code String}
* @return an array of the tokens in the list
* @see #tokenizeToStringArray
*/
public static String[] delimitedListToStringArray(String str, String delimiter, String charsToDelete) {
if (str == null) {
return new String[0];
}
if (delimiter == null) {
return new String[] {str};
}
List result = new ArrayList();
if ("".equals(delimiter)) {
for (int i = 0; i < str.length(); i++) {
result.add(deleteAny(str.substring(i, i + 1), charsToDelete));
}
}
else {
int pos = 0;
int delPos;
while ((delPos = str.indexOf(delimiter, pos)) != -1) {
result.add(deleteAny(str.substring(pos, delPos), charsToDelete));
pos = delPos + delimiter.length();
}
if (str.length() > 0 && pos <= str.length()) {
// Add rest of String, but not in case of empty input.
result.add(deleteAny(str.substring(pos), charsToDelete));
}
}
return toStringArray(result);
}
/**
* Convert a comma delimited list (e.g., a row from a CSV file) into an
* array of strings.
* @param str the input {@code String}
* @return an array of strings, or the empty array in case of empty input
*/
public static String[] commaDelimitedListToStringArray(String str) {
return delimitedListToStringArray(str, ",");
}
/**
* Convert a comma delimited list (e.g., a row from a CSV file) into a set.
* Note that this will suppress duplicates, and as of 4.2, the elements in
* the returned set will preserve the original order in a {@link LinkedHashSet}.
* @param str the input {@code String}
* @return a set of {@code String} entries in the list
* @see #removeDuplicateStrings(String[])
*/
public static Set commaDelimitedListToSet(String str) {
Set set = new LinkedHashSet();
String[] tokens = commaDelimitedListToStringArray(str);
for (String token : tokens) {
set.add(token);
}
return set;
}
/**
* Convert a {@link Collection} to a delimited {@code String} (e.g. CSV).
* Useful for {@code toString()} implementations.
* @param coll the {@code Collection} to convert
* @param delim the delimiter to use (typically a ",")
* @param prefix the {@code String} to start each element with
* @param suffix the {@code String} to end each element with
* @return the delimited {@code String}
*/
public static String collectionToDelimitedString(Collection coll, String delim, String prefix, String suffix) {
if (coll == null || coll.isEmpty()) {
return "";
}
StringBuilder sb = new StringBuilder();
Iterator it = coll.iterator();
while (it.hasNext()) {
sb.append(prefix).append(it.next()).append(suffix);
if (it.hasNext()) {
sb.append(delim);
}
}
return sb.toString();
}
/**
* Convert a {@code Collection} into a delimited {@code String} (e.g. CSV).
*
Useful for {@code toString()} implementations.
* @param coll the {@code Collection} to convert
* @param delim the delimiter to use (typically a ",")
* @return the delimited {@code String}
*/
public static String collectionToDelimitedString(Collection coll, String delim) {
return collectionToDelimitedString(coll, delim, "", "");
}
/**
* Convert a {@code Collection} into a delimited {@code String} (e.g., CSV).
*
Useful for {@code toString()} implementations.
* @param coll the {@code Collection} to convert
* @return the delimited {@code String}
*/
public static String collectionToCommaDelimitedString(Collection coll) {
return collectionToDelimitedString(coll, ",");
}
/**
* Copy the given {@code Collection} into a {@code String} array.
*
The {@code Collection} must contain {@code String} elements only.
* @param collection the {@code Collection} to copy
* @return the {@code String} array ({@code null} if the supplied
* {@code Collection} was {@code null})
*/
public static String[] toStringArray(Collection collection) {
if (collection == null) {
return null;
}
return collection.toArray(new String[collection.size()]);
}
/**
* Copy the given Enumeration into a {@code String} array.
* The Enumeration must contain {@code String} elements only.
* @param enumeration the Enumeration to copy
* @return the {@code String} array ({@code null} if the passed-in
* Enumeration was {@code null})
*/
public static String[] toStringArray(Enumeration enumeration) {
if (enumeration == null) {
return null;
}
List list = Collections.list(enumeration);
return list.toArray(new String[list.size()]);
}
/**
* Delete any character in a given {@code String}.
* @param inString the original {@code String}
* @param charsToDelete a set of characters to delete.
* E.g. "az\n" will delete 'a's, 'z's and new lines.
* @return the resulting {@code String}
*/
public static String deleteAny(String inString, String charsToDelete) {
if (isEmpty(inString) || isEmpty(charsToDelete)) {
return inString;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < inString.length(); i++) {
char c = inString.charAt(i);
if (charsToDelete.indexOf(c) == -1) {
sb.append(c);
}
}
return sb.toString();
}
}