StringUtils工具类介绍
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public abstract class StringUtils {
private static final String[] EMPTY_STRING_ARRAY = {};
private static final String FOLDER_SEPARATOR = "/";
private static final String WINDOWS_FOLDER_SEPARATOR = "\\";
private static final String TOP_PATH = "..";
private static final String CURRENT_PATH = ".";
private static final char EXTENSION_SEPARATOR = '.';
//---------------------------------------------------------------------
// General convenience methods for working with Strings
//---------------------------------------------------------------------
/**
* Check whether the given object (possibly a {@code String}) is empty.
* This is effectively a shortcut for {@code !hasLength(String)}.
* <p>This method accepts any Object as an argument, comparing it to
* {@code null} and the empty String. As a consequence, this method
* will never return {@code true} for a non-null non-String object.
* <p>The Object signature is useful for general attribute handling code
* that commonly deals with Strings but generally has to iterate over
* Objects since attributes may e.g. be primitive value objects as well.
* <p><b>Note: If the object is typed to {@code String} upfront, prefer
* {@link #hasLength(String)} or {@link #hasText(String)} instead.</b>
* @param str the candidate object (possibly a {@code String})
* @since 3.2.1
* @see #hasLength(String)
* @see #hasText(String)
*/
public static boolean isEmpty(@Nullable Object str) {
return (str == null || "".equals(str));
}
/**
* Check that the given {@code CharSequence} is neither {@code null} nor
* of length 0.
* <p>Note: this method returns {@code true} for a {@code CharSequence}
* that purely consists of whitespace.
* <p><pre class="code">
* StringUtils.hasLength(null) = false
* StringUtils.hasLength("") = false
* StringUtils.hasLength(" ") = true
* StringUtils.hasLength("Hello") = true
* </pre>
* @param str the {@code CharSequence} to check (may be {@code null})
* @return {@code true} if the {@code CharSequence} is not {@code null} and has length
* @see #hasLength(String)
* @see #hasText(CharSequence)
*/
public static boolean hasLength(@Nullable CharSequence str) {
return (str != null && str.length() > 0);
}
/**
* Check that the given {@code String} is neither {@code null} nor of length 0.
* <p>Note: this method returns {@code true} for a {@code String} that
* purely consists of whitespace.
* @param str the {@code String} to check (may be {@code null})
* @return {@code true} if the {@code String} is not {@code null} and has length
* @see #hasLength(CharSequence)
* @see #hasText(String)
*/
public static boolean hasLength(@Nullable String str) {
return (str != null && !str.isEmpty());
}
/**
* Check whether the given {@code CharSequence} contains actual <em>text</em>.
* <p>More specifically, this method returns {@code true} if the
* {@code CharSequence} is not {@code null}, its length is greater than
* 0, and it contains at least one non-whitespace character.
* <p><pre class="code">
* StringUtils.hasText(null) = false
* StringUtils.hasText("") = false
* StringUtils.hasText(" ") = false
* StringUtils.hasText("12345") = true
* StringUtils.hasText(" 12345 ") = true
* </pre>
* @param str the {@code CharSequence} to check (may be {@code null})
* @return {@code true} if the {@code CharSequence} is not {@code null},
* its length is greater than 0, and it does not contain whitespace only
* @see #hasText(String)
* @see #hasLength(CharSequence)
* @see Character#isWhitespace
*/
public static boolean hasText(@Nullable CharSequence str) {
return (str != null && str.length() > 0 && containsText(str));
}
/**
* Check whether the given {@code String} contains actual <em>text</em>.
* <p>More specifically, this method returns {@code true} if the
* {@code String} is not {@code null}, its length is greater than 0,
* and it contains at least one non-whitespace character.
* @param str the {@code String} to check (may be {@code null})
* @return {@code true} if the {@code String} is not {@code null}, its
* length is greater than 0, and it does not contain whitespace only
* @see #hasText(CharSequence)
* @see #hasLength(String)
* @see Character#isWhitespace
*/
public static boolean hasText(@Nullable String str) {
return (str != null && !str.isEmpty() && containsText(str));
}
private static boolean containsText(CharSequence str) {
int strLen = str.length();
for (int i = 0; i < strLen; i++) {
if (!Character.isWhitespace(str.charAt(i))) {
return true;
}
}
return false;
}
/**
* Check whether the given {@code CharSequence} contains any whitespace characters.
* @param str the {@code CharSequence} to check (may be {@code null})
* @return {@code true} if the {@code CharSequence} is not empty and
* contains at least 1 whitespace character
* @see Character#isWhitespace
*/
public static boolean containsWhitespace(@Nullable CharSequence str) {
if (!hasLength(str)) {
return false;
}
int strLen = str.length();
for (int i = 0; i < strLen; i++) {
if (Character.isWhitespace(str.charAt(i))) {
return true;
}
}
return false;
}
/**
* Check whether the given {@code String} contains any whitespace characters.
* @param str the {@code String} to check (may be {@code null})
* @return {@code true} if the {@code String} is not empty and
* contains at least 1 whitespace character
* @see #containsWhitespace(CharSequence)
*/
public static boolean containsWhitespace(@Nullable String str) {
return containsWhitespace((CharSequence) str);
}
/**
* Trim leading and trailing whitespace from the given {@code String}.
* @param str the {@code String} to check
* @return the trimmed {@code String}
* @see java.lang.Character#isWhitespace
*/
public static String trimWhitespace(String str) {
if (!hasLength(str)) {
return str;
}
int beginIndex = 0;
int endIndex = str.length() - 1;
while (beginIndex <= endIndex && Character.isWhitespace(str.charAt(beginIndex))) {
beginIndex++;
}
while (endIndex > beginIndex && Character.isWhitespace(str.charAt(endIndex))) {
endIndex--;
}
return str.substring(beginIndex, endIndex + 1);
}
/**
* Trim <i>all</i> whitespace from the given {@code String}:
* leading, trailing, and in between characters.
* @param str the {@code String} to check
* @return the trimmed {@code String}
* @see java.lang.Character#isWhitespace
*/
public static String trimAllWhitespace(String str) {
if (!hasLength(str)) {
return str;
}
int len = str.length();
StringBuilder sb = new StringBuilder(str.length());
for (int i = 0; i < len; i++) {
char c = str.charAt(i);
if (!Character.isWhitespace(c)) {
sb.append(c);
}
}
return sb.toString();
}
/**
* Trim leading whitespace from the given {@code String}.
* @param str the {@code String} to check
* @return the trimmed {@code String}
* @see java.lang.Character#isWhitespace
*/
public static String trimLeadingWhitespace(String str) {
if (!hasLength(str)) {
return str;
}
StringBuilder sb = new StringBuilder(str);
while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
sb.deleteCharAt(0);
}
return sb.toString();
}
/**
* Trim trailing whitespace from the given {@code String}.
* @param str the {@code String} to check
* @return the trimmed {@code String}
* @see java.lang.Character#isWhitespace
*/
public static String trimTrailingWhitespace(String str) {
if (!hasLength(str)) {
return str;
}
StringBuilder sb = new StringBuilder(str);
while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
sb.deleteCharAt(sb.length() - 1);
}
return sb.toString();
}
/**
* Trim all occurrences of the supplied leading character from the given {@code String}.
* @param str the {@code String} to check
* @param leadingCharacter the leading character to be trimmed
* @return the trimmed {@code String}
*/
public static String trimLeadingCharacter(String str, char leadingCharacter) {
if (!hasLength(str)) {
return str;
}
StringBuilder sb = new StringBuilder(str);
while (sb.length() > 0 && sb.charAt(0) == leadingCharacter) {
sb.deleteCharAt(0);
}
return sb.toString();
}
/**
* Trim all occurrences of the supplied trailing character from the given {@code String}.
* @param str the {@code String} to check
* @param trailingCharacter the trailing character to be trimmed
* @return the trimmed {@code String}
*/
public static String trimTrailingCharacter(String str, char trailingCharacter) {
if (!hasLength(str)) {
return str;
}
StringBuilder sb = new StringBuilder(str);
while (sb.length() > 0 && sb.charAt(sb.length() - 1) == trailingCharacter) {
sb.deleteCharAt(sb.length() - 1);
}
return sb.toString();
}
/**
* Test if the given {@code String} starts with the specified prefix,
* ignoring upper/lower case.
* @param str the {@code String} to check
* @param prefix the prefix to look for
* @see java.lang.String#startsWith
*/
public static boolean startsWithIgnoreCase(@Nullable String str, @Nullable String prefix) {
return (str != null && prefix != null && str.length() >= prefix.length() &&
str.regionMatches(true, 0, prefix, 0, prefix.length()));
}
/**
* Test if the given {@code String} ends with the specified suffix,
* ignoring upper/lower case.
* @param str the {@code String} to check
* @param suffix the suffix to look for
* @see java.lang.String#endsWith
*/
public static boolean endsWithIgnoreCase(@Nullable String str, @Nullable String suffix) {
return (str != null && suffix != null && str.length() >= suffix.length() &&
str.regionMatches(true, str.length() - suffix.length(), suffix, 0, suffix.length()));
}
/**
* Test whether the given string matches the given substring
* at the given index.
* @param str the original string (or StringBuilder)
* @param index the index in the original string to start matching against
* @param substring the substring to match at the given index
*/
public static boolean substringMatch(CharSequence str, int index, CharSequence substring) {
if (index + substring.length() > str.length()) {
return false;
}
for (int i = 0; i < substring.length(); i++) {
if (str.charAt(index + i) != substring.charAt(i)) {
return false;
}
}
return true;
}
/**
* Count the occurrences of the substring {@code sub} in string {@code str}.
* @param str string to search in
* @param sub string to search for
*/
public static int countOccurrencesOf(String str, String sub) {
if (!hasLength(str) || !hasLength(sub)) {
return 0;
}
int count = 0;
int pos = 0;
int idx;
while ((idx = str.indexOf(sub, pos)) != -1) {
++count;
pos = idx + sub.length();
}
return count;
}
/**
* Replace all occurrences of a substring within a string with another string.
* @param inString {@code String} to examine
* @param oldPattern {@code String} to replace
* @param newPattern {@code String} to insert
* @return a {@code String} with the replacements
*/
public static String replace(String inString, String oldPattern, @Nullable String newPattern) {
if (!hasLength(inString) || !hasLength(oldPattern) || newPattern == null) {
return inString;
}
int index = inString.indexOf(oldPattern);
if (index == -1) {
// no occurrence -> can return input as-is
return inString;
}
int capacity = inString.length();
if (newPattern.length() > oldPattern.length()) {
capacity += 16;
}
StringBuilder sb = new StringBuilder(capacity);
int pos = 0; // our position in the old string
int patLen = oldPattern.length();
while (index >= 0) {
sb.append(inString, pos, index);
sb.append(newPattern);
pos = index + patLen;
index = inString.indexOf(oldPattern, pos);
}
// append any characters to the right of a match
sb.append(inString, pos, inString.length());
return sb.toString();
}
/**
* Delete all occurrences of the given substring.
* @param inString the original {@code String}
* @param pattern the pattern to delete all occurrences of
* @return the resulting {@code String}
*/
public static String delete(String inString, String pattern) {
return replace(inString, pattern, "");
}
/**
* 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, @Nullable String charsToDelete) {
if (!hasLength(inString) || !hasLength(charsToDelete)) {
return inString;
}
StringBuilder sb = new StringBuilder(inString.length());
for (int i = 0; i < inString.length(); i++) {
char c = inString.charAt(i);
if (charsToDelete.indexOf(c) == -1) {
sb.append(c);
}
}
return sb.toString();
}
//---------------------------------------------------------------------
// Convenience methods for working with formatted Strings
//---------------------------------------------------------------------
/**
* Quote the given {@code String} with single quotes.
* @param str the input {@code String} (e.g. "myString")
* @return the quoted {@code String} (e.g. "'myString'"),
* or {@code null} if the input was {@code null}
*/
@Nullable
public static String quote(@Nullable String str) {
return (str != null ? "'" + str + "'" : null);
}
/**
* Turn the given Object into a {@code String} with single quotes
* if it is a {@code String}; keeping the Object as-is else.
* @param obj the input Object (e.g. "myString")
* @return the quoted {@code String} (e.g. "'myString'"),
* or the input object as-is if not a {@code String}
*/
@Nullable
public static Object quoteIfString(@Nullable Object obj) {
return (obj instanceof String ? quote((String) obj) : obj);
}
/**
* Unqualify a string qualified by a '.' dot character. For example,
* "this.name.is.qualified", returns "qualified".
* @param qualifiedName the qualified name
*/
public static String unqualify(String qualifiedName) {
return unqualify(qualifiedName, '.');
}
/**
* Unqualify a string qualified by a separator character. For example,
* "this:name:is:qualified" returns "qualified" if using a ':' separator.
* @param qualifiedName the qualified name
* @param separator the separator
*/
public static String unqualify(String qualifiedName, char separator) {
return qualifiedName.substring(qualifiedName.lastIndexOf(separator) + 1);
}
/**
* Capitalize a {@code String}, changing the first letter to
* upper case as per {@link Character#toUpperCase(char)}.
* No other letters are changed.
* @param str the {@code String} to capitalize
* @return the capitalized {@code String}
*/
public static String capitalize(String str) {
return changeFirstCharacterCase(str, true);
}
/**
* Uncapitalize a {@code String}, changing the first letter to
* lower case as per {@link Character#toLowerCase(char)}.
* No other letters are changed.
* @param str the {@code String} to uncapitalize
* @return the uncapitalized {@code String}
*/
public static String uncapitalize(String str) {
return changeFirstCharacterCase(str, false);
}
private static String changeFirstCharacterCase(String str, boolean capitalize) {
if (!hasLength(str)) {
return str;
}
char baseChar = str.charAt(0);
char updatedChar;
if (capitalize) {
updatedChar = Character.toUpperCase(baseChar);
}
else {
updatedChar = Character.toLowerCase(baseChar);
}
if (baseChar == updatedChar) {
return str;
}
char[] chars = str.toCharArray();
chars[0] = updatedChar;
return new String(chars, 0, chars.length);
}
/**
* Extract the filename from the given Java resource path,
* e.g. {@code "mypath/myfile.txt" -> "myfile.txt"}.
* @param path the file path (may be {@code null})
* @return the extracted filename, or {@code null} if none
*/
@Nullable
public static String getFilename(@Nullable String path) {
if (path == null) {
return null;
}
int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
return (separatorIndex != -1 ? path.substring(separatorIndex + 1) : path);
}
/**
* Extract the filename extension from the given Java resource path,
* e.g. "mypath/myfile.txt" -> "txt".
* @param path the file path (may be {@code null})
* @return the extracted filename extension, or {@code null} if none
*/
@Nullable
public static String getFilenameExtension(@Nullable String path) {
if (path == null) {
return null;
}
int extIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
if (extIndex == -1) {
return null;
}
int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR);
if (folderIndex > extIndex) {
return null;
}
return path.substring(extIndex + 1);
}
/**
* Strip the filename extension from the given Java resource path,
* e.g. "mypath/myfile.txt" -> "mypath/myfile".
* @param path the file path
* @return the path with stripped filename extension
*/
public static String stripFilenameExtension(String path) {
int extIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
if (extIndex == -1) {
return path;
}
int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR);
if (folderIndex > extIndex) {
return path;
}
return path.substring(0, extIndex);
}
/**
* Apply the given relative path to the given Java resource path,
* assuming standard Java folder separation (i.e. "/" separators).
* @param path the path to start from (usually a full file path)
* @param relativePath the relative path to apply
* (relative to the full file path above)
* @return the full file path that results from applying the relative path
*/
public static String applyRelativePath(String path, String relativePath) {
int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
if (separatorIndex != -1) {
String newPath = path.substring(0, separatorIndex);
if (!relativePath.startsWith(FOLDER_SEPARATOR)) {
newPath += FOLDER_SEPARATOR;
}
return newPath + relativePath;
}
else {
return relativePath;
}
}
/**
* Normalize the path by suppressing sequences like "path/.." and
* inner simple dots.
* <p>The result is convenient for path comparison. For other uses,
* notice that Windows separators ("\") are replaced by simple slashes.
* @param path the original path
* @return the normalized path
*/
public static String cleanPath(String path) {
if (!hasLength(path)) {
return path;
}
String pathToUse = replace(path, WINDOWS_FOLDER_SEPARATOR, FOLDER_SEPARATOR);
// Shortcut if there is no work to do
if (pathToUse.indexOf('.') == -1) {
return pathToUse;
}
// Strip prefix from path to analyze, to not treat it as part of the
// first path element. This is necessary to correctly parse paths like
// "file:core/../core/io/Resource.class", where the ".." should just
// strip the first "core" directory while keeping the "file:" prefix.
int prefixIndex = pathToUse.indexOf(':');
String prefix = "";
if (prefixIndex != -1) {
prefix = pathToUse.substring(0, prefixIndex + 1);
if (prefix.contains(FOLDER_SEPARATOR)) {
prefix = "";
}
else {
pathToUse = pathToUse.substring(prefixIndex + 1);
}
}
if (pathToUse.startsWith(FOLDER_SEPARATOR)) {
prefix = prefix + FOLDER_SEPARATOR;
pathToUse = pathToUse.substring(1);
}
String[] pathArray = delimitedListToStringArray(pathToUse, FOLDER_SEPARATOR);
LinkedList<String> pathElements = new LinkedList<>();
int tops = 0;
for (int i = pathArray.length - 1; i >= 0; i--) {
String element = pathArray[i];
if (CURRENT_PATH.equals(element)) {
// Points to current directory - drop it.
}
else if (TOP_PATH.equals(element)) {
// Registering top path found.
tops++;
}
else {
if (tops > 0) {
// Merging path element with element corresponding to top path.
tops--;
}
else {
// Normal path element found.
pathElements.add(0, element);
}
}
}
// All path elements stayed the same - shortcut
if (pathArray.length == pathElements.size()) {
return prefix + pathToUse;
}
// Remaining top paths need to be retained.
for (int i = 0; i < tops; i++) {
pathElements.add(0, TOP_PATH);
}
// If nothing else left, at least explicitly point to current path.
if (pathElements.size() == 1 && "".equals(pathElements.getLast()) && !prefix.endsWith(FOLDER_SEPARATOR)) {
pathElements.add(0, CURRENT_PATH);
}
return prefix + collectionToDelimitedString(pathElements, FOLDER_SEPARATOR);
}
/**
* Compare two paths after normalization of them.
* @param path1 first path for comparison
* @param path2 second path for comparison
* @return whether the two paths are equivalent after normalization
*/
public static boolean pathEquals(String path1, String path2) {
return cleanPath(path1).equals(cleanPath(path2));
}
/**
* Decode the given encoded URI component value. Based on the following rules:
* <ul>
* <li>Alphanumeric characters {@code "a"} through {@code "z"}, {@code "A"} through {@code "Z"},
* and {@code "0"} through {@code "9"} stay the same.</li>
* <li>Special characters {@code "-"}, {@code "_"}, {@code "."}, and {@code "*"} stay the same.</li>
* <li>A sequence "{@code %<i>xy</i>}" is interpreted as a hexadecimal representation of the character.</li>
* </ul>
* @param source the encoded String
* @param charset the character set
* @return the decoded value
* @throws IllegalArgumentException when the given source contains invalid encoded sequences
* @since 5.0
* @see java.net.URLDecoder#decode(String, String)
*/
public static String uriDecode(String source, Charset charset) {
int length = source.length();
if (length == 0) {
return source;
}
Assert.notNull(charset, "Charset must not be null");
ByteArrayOutputStream baos = new ByteArrayOutputStream(length);
boolean changed = false;
for (int i = 0; i < length; i++) {
int ch = source.charAt(i);
if (ch == '%') {
if (i + 2 < length) {
char hex1 = source.charAt(i + 1);
char hex2 = source.charAt(i + 2);
int u = Character.digit(hex1, 16);
int l = Character.digit(hex2, 16);
if (u == -1 || l == -1) {
throw new IllegalArgumentException("Invalid encoded sequence \"" + source.substring(i) + "\"");
}
baos.write((char) ((u << 4) + l));
i += 2;
changed = true;
}
else {
throw new IllegalArgumentException("Invalid encoded sequence \"" + source.substring(i) + "\"");
}
}
else {
baos.write(ch);
}
}
return (changed ? StreamUtils.copyToString(baos, charset) : source);
}
/**
* Parse the given {@code String} value into a {@link Locale}, accepting
* the {@link Locale#toString} format as well as BCP 47 language tags.
* @param localeValue the locale value: following either {@code Locale's}
* {@code toString()} format ("en", "en_UK", etc), also accepting spaces as
* separators (as an alternative to underscores), or BCP 47 (e.g. "en-UK")
* as specified by {@link Locale#forLanguageTag} on Java 7+
* @return a corresponding {@code Locale} instance, or {@code null} if none
* @throws IllegalArgumentException in case of an invalid locale specification
* @since 5.0.4
* @see #parseLocaleString
* @see Locale#forLanguageTag
*/
@Nullable
public static Locale parseLocale(String localeValue) {
String[] tokens = tokenizeLocaleSource(localeValue);
if (tokens.length == 1) {
validateLocalePart(localeValue);
Locale resolved = Locale.forLanguageTag(localeValue);
if (resolved.getLanguage().length() > 0) {
return resolved;
}
}
return parseLocaleTokens(localeValue, tokens);
}
/**
* Parse the given {@code String} representation into a {@link Locale}.
* <p>For many parsing scenarios, this is an inverse operation of
* {@link Locale#toString Locale's toString}, in a lenient sense.
* This method does not aim for strict {@code Locale} design compliance;
* it is rather specifically tailored for typical Spring parsing needs.
* <p><b>Note: This delegate does not accept the BCP 47 language tag format.
* Please use {@link #parseLocale} for lenient parsing of both formats.</b>
* @param localeString the locale {@code String}: following {@code Locale's}
* {@code toString()} format ("en", "en_UK", etc), also accepting spaces as
* separators (as an alternative to underscores)
* @return a corresponding {@code Locale} instance, or {@code null} if none
* @throws IllegalArgumentException in case of an invalid locale specification
*/
@Nullable
public static Locale parseLocaleString(String localeString) {
return parseLocaleTokens(localeString, tokenizeLocaleSource(localeString));
}
private static String[] tokenizeLocaleSource(String localeSource) {
return tokenizeToStringArray(localeSource, "_ ", false, false);
}
@Nullable
private static Locale parseLocaleTokens(String localeString, String[] tokens) {
String language = (tokens.length > 0 ? tokens[0] : "");
String country = (tokens.length > 1 ? tokens[1] : "");
validateLocalePart(language);
validateLocalePart(country);
String variant = "";
if (tokens.length > 2) {
// There is definitely a variant, and it is everything after the country
// code sans the separator between the country code and the variant.
int endIndexOfCountryCode = localeString.indexOf(country, language.length()) + country.length();
// Strip off any leading '_' and whitespace, what's left is the variant.
variant = trimLeadingWhitespace(localeString.substring(endIndexOfCountryCode));
if (variant.startsWith("_")) {
variant = trimLeadingCharacter(variant, '_');
}
}
if (variant.isEmpty() && country.startsWith("#")) {
variant = country;
country = "";
}
return (language.length() > 0 ? new Locale(language, country, variant) : null);
}
private static void validateLocalePart(String localePart) {
for (int i = 0; i < localePart.length(); i++) {
char ch = localePart.charAt(i);
if (ch != ' ' && ch != '_' && ch != '-' && ch != '#' && !Character.isLetterOrDigit(ch)) {
throw new IllegalArgumentException(
"Locale part \"" + localePart + "\" contains invalid characters");
}
}
}
/**
* Determine the RFC 3066 compliant language tag,
* as used for the HTTP "Accept-Language" header.
* @param locale the Locale to transform to a language tag
* @return the RFC 3066 compliant language tag as {@code String}
* @deprecated as of 5.0.4, in favor of {@link Locale#toLanguageTag()}
*/
@Deprecated
public static String toLanguageTag(Locale locale) {
return locale.getLanguage() + (hasText(locale.getCountry()) ? "-" + locale.getCountry() : "");
}
/**
* Parse the given {@code timeZoneString} value into a {@link TimeZone}.
* @param timeZoneString the time zone {@code String}, following {@link TimeZone#getTimeZone(String)}
* but throwing {@link IllegalArgumentException} in case of an invalid time zone specification
* @return a corresponding {@link TimeZone} instance
* @throws IllegalArgumentException in case of an invalid time zone specification
*/
public static TimeZone parseTimeZoneString(String timeZoneString) {
TimeZone timeZone = TimeZone.getTimeZone(timeZoneString);
if ("GMT".equals(timeZone.getID()) && !timeZoneString.startsWith("GMT")) {
// We don't want that GMT fallback...
throw new IllegalArgumentException("Invalid time zone specification '" + timeZoneString + "'");
}
return timeZone;
}
//---------------------------------------------------------------------
// Convenience methods for working with String arrays
//---------------------------------------------------------------------
/**
* Copy the given {@link Collection} into a {@code String} array.
* <p>The {@code Collection} must contain {@code String} elements only.
* @param collection the {@code Collection} to copy
* (potentially {@code null} or empty)
* @return the resulting {@code String} array
*/
public static String[] toStringArray(@Nullable Collection<String> collection) {
return (!CollectionUtils.isEmpty(collection) ? collection.toArray(EMPTY_STRING_ARRAY) : EMPTY_STRING_ARRAY);
}
/**
* Copy the given {@link Enumeration} into a {@code String} array.
* <p>The {@code Enumeration} must contain {@code String} elements only.
* @param enumeration the {@code Enumeration} to copy
* (potentially {@code null} or empty)
* @return the resulting {@code String} array
*/
public static String[] toStringArray(@Nullable Enumeration<String> enumeration) {
return (enumeration != null ? toStringArray(Collections.list(enumeration)) : EMPTY_STRING_ARRAY);
}
/**
* Append the given {@code String} to the given {@code String} array,
* returning a new array consisting of the input array contents plus
* the given {@code String}.
* @param array the array to append to (can be {@code null})
* @param str the {@code String} to append
* @return the new array (never {@code null})
*/
public static String[] addStringToArray(@Nullable String[] array, String str) {
if (ObjectUtils.isEmpty(array)) {
return new String[] {str};
}
String[] newArr = new String[array.length + 1];
System.arraycopy(array, 0, newArr, 0, array.length);
newArr[array.length] = str;
return newArr;
}
/**
* Concatenate the given {@code String} arrays into one,
* with overlapping array elements included twice.
* <p>The order of elements in the original arrays is preserved.
* @param array1 the first array (can be {@code null})
* @param array2 the second array (can be {@code null})
* @return the new array ({@code null} if both given arrays were {@code null})
*/
@Nullable
public static String[] concatenateStringArrays(@Nullable String[] array1, @Nullable String[] array2) {
if (ObjectUtils.isEmpty(array1)) {
return array2;
}
if (ObjectUtils.isEmpty(array2)) {
return array1;
}
String[] newArr = new String[array1.length + array2.length];
System.arraycopy(array1, 0, newArr, 0, array1.length);
System.arraycopy(array2, 0, newArr, array1.length, array2.length);
return newArr;
}
/**
* Merge the given {@code String} arrays into one, with overlapping
* array elements only included once.
* <p>The order of elements in the original arrays is preserved
* (with the exception of overlapping elements, which are only
* included on their first occurrence).
* @param array1 the first array (can be {@code null})
* @param array2 the second array (can be {@code null})
* @return the new array ({@code null} if both given arrays were {@code null})
* @deprecated as of 4.3.15, in favor of manual merging via {@link LinkedHashSet}
* (with every entry included at most once, even entries within the first array)
*/
@Deprecated
@Nullable
public static String[] mergeStringArrays(@Nullable String[] array1, @Nullable String[] array2) {
if (ObjectUtils.isEmpty(array1)) {
return array2;
}
if (ObjectUtils.isEmpty(array2)) {
return array1;
}
List<String> result = new ArrayList<>(Arrays.asList(array1));
for (String str : array2) {
if (!result.contains(str)) {
result.add(str);
}
}
return toStringArray(result);
}
/**
* Sort the given {@code String} array if necessary.
* @param array the original array (potentially empty)
* @return the array in sorted form (never {@code null})
*/
public static String[] sortStringArray(String[] array) {
if (ObjectUtils.isEmpty(array)) {
return array;
}
Arrays.sort(array);
return array;
}
/**
* Trim the elements of the given {@code String} array, calling
* {@code String.trim()} on each non-null element.
* @param array the original {@code String} array (potentially empty)
* @return the resulting array (of the same size) with trimmed elements
*/
public static String[] trimArrayElements(String[] array) {
if (ObjectUtils.isEmpty(array)) {
return array;
}
String[] result = new String[array.length];
for (int i = 0; i < array.length; i++) {
String element = array[i];
result[i] = (element != null ? element.trim() : null);
}
return result;
}
/**
* Remove duplicate strings from the given array.
* <p>As of 4.2, it preserves the original order, as it uses a {@link LinkedHashSet}.
* @param array the {@code String} array (potentially empty)
* @return an array without duplicates, in natural sort order
*/
public static String[] removeDuplicateStrings(String[] array) {
if (ObjectUtils.isEmpty(array)) {
return array;
}
Set<String> set = new LinkedHashSet<>(Arrays.asList(array));
return toStringArray(set);
}
/**
* Split a {@code String} at the first occurrence of the delimiter.
* Does not include the delimiter in the result.
* @param toSplit the string to split (potentially {@code null} or empty)
* @param delimiter to split the string up with (potentially {@code null} or empty)
* @return a two element array with index 0 being before the delimiter, and
* index 1 being after the delimiter (neither element includes the delimiter);
* or {@code null} if the delimiter wasn't found in the given input {@code String}
*/
@Nullable
public static String[] split(@Nullable String toSplit, @Nullable String delimiter) {
if (!hasLength(toSplit) || !hasLength(delimiter)) {
return null;
}
int offset = toSplit.indexOf(delimiter);
if (offset < 0) {
return null;
}
String beforeDelimiter = toSplit.substring(0, offset);
String afterDelimiter = toSplit.substring(offset + delimiter.length());
return new String[] {beforeDelimiter, afterDelimiter};
}
/**
* Take an array of strings and split each element based on the given delimiter.
* A {@code Properties} instance is then generated, with the left of the delimiter
* providing the key, and the right of the delimiter providing the value.
* <p>Will trim both the key and value before adding them to the {@code Properties}.
* @param array the array to process
* @param delimiter to split each element using (typically the equals symbol)
* @return a {@code Properties} instance representing the array contents,
* or {@code null} if the array to process was {@code null} or empty
*/
@Nullable
public static Properties splitArrayElementsIntoProperties(String[] array, String delimiter) {
return splitArrayElementsIntoProperties(array, delimiter, null);
}
/**
* Take an array of strings and split each element based on the given delimiter.
* A {@code Properties} instance is then generated, with the left of the
* delimiter providing the key, and the right of the delimiter providing the value.
* <p>Will trim both the key and value before adding them to the
* {@code Properties} instance.
* @param array the array to process
* @param delimiter to split each element using (typically the equals symbol)
* @param charsToDelete one or more characters to remove from each element
* prior to attempting the split operation (typically the quotation mark
* symbol), or {@code null} if no removal should occur
* @return a {@code Properties} instance representing the array contents,
* or {@code null} if the array to process was {@code null} or empty
*/
@Nullable
public static Properties splitArrayElementsIntoProperties(
String[] array, String delimiter, @Nullable String charsToDelete) {
if (ObjectUtils.isEmpty(array)) {
return null;
}
Properties result = new Properties();
for (String element : array) {
if (charsToDelete != null) {
element = deleteAny(element, charsToDelete);
}
String[] splittedElement = split(element, delimiter);
if (splittedElement == null) {
continue;
}
result.setProperty(splittedElement[0].trim(), splittedElement[1].trim());
}
return result;
}
/**
* Tokenize the given {@code String} into a {@code String} array via a
* {@link StringTokenizer}.
* <p>Trims tokens and omits empty tokens.
* <p>The given {@code delimiters} string can consist of any number of
* delimiter characters. Each of those characters can be used to separate
* tokens. A delimiter is always a single character; for multi-character
* delimiters, consider using {@link #delimitedListToStringArray}.
* @param str the {@code String} to tokenize (potentially {@code null} or empty)
* @param delimiters the delimiter characters, assembled as a {@code String}
* (each of the characters is individually considered as a delimiter)
* @return an array of the tokens
* @see java.util.StringTokenizer
* @see String#trim()
* @see #delimitedListToStringArray
*/
public static String[] tokenizeToStringArray(@Nullable String str, String delimiters) {
return tokenizeToStringArray(str, delimiters, true, true);
}
/**
* Tokenize the given {@code String} into a {@code String} array via a
* {@link StringTokenizer}.
* <p>The given {@code delimiters} string can consist of any number of
* delimiter characters. Each of those characters can be used to separate
* tokens. A delimiter is always a single character; for multi-character
* delimiters, consider using {@link #delimitedListToStringArray}.
* @param str the {@code String} to tokenize (potentially {@code null} or empty)
* @param delimiters the delimiter characters, assembled as a {@code String}
* (each of the characters is individually considered as a delimiter)
* @param trimTokens trim the tokens via {@link String#trim()}
* @param ignoreEmptyTokens omit empty tokens from the result array
* (only applies to tokens that are empty after trimming; StringTokenizer
* will not consider subsequent delimiters as token in the first place).
* @return an array of the tokens
* @see java.util.StringTokenizer
* @see String#trim()
* @see #delimitedListToStringArray
*/
public static String[] tokenizeToStringArray(
@Nullable String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens) {
if (str == null) {
return EMPTY_STRING_ARRAY;
}
StringTokenizer st = new StringTokenizer(str, delimiters);
List<String> tokens = new ArrayList<>();
while (st.hasMoreTokens()) {
String token = st.nextToken();
if (trimTokens) {
token = token.trim();
}
if (!ignoreEmptyTokens || token.length() > 0) {
tokens.add(token);
}
}
return toStringArray(tokens);
}
/**
* Take a {@code String} that is a delimited list and convert it into a
* {@code String} array.
* <p>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} (potentially {@code null} or empty)
* @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(@Nullable String str, @Nullable String delimiter) {
return delimitedListToStringArray(str, delimiter, null);
}
/**
* Take a {@code String} that is a delimited list and convert it into
* a {@code String} array.
* <p>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} (potentially {@code null} or empty)
* @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(
@Nullable String str, @Nullable String delimiter, @Nullable String charsToDelete) {
if (str == null) {
return EMPTY_STRING_ARRAY;
}
if (delimiter == null) {
return new String[] {str};
}
List<String> result = new ArrayList<>();
if (delimiter.isEmpty()) {
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} (potentially {@code null} or empty)
* @return an array of strings, or the empty array in case of empty input
*/
public static String[] commaDelimitedListToStringArray(@Nullable String str) {
return delimitedListToStringArray(str, ",");
}
/**
* Convert a comma delimited list (e.g., a row from a CSV file) into a set.
* <p>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} (potentially {@code null} or empty)
* @return a set of {@code String} entries in the list
* @see #removeDuplicateStrings(String[])
*/
public static Set<String> commaDelimitedListToSet(@Nullable String str) {
String[] tokens = commaDelimitedListToStringArray(str);
return new LinkedHashSet<>(Arrays.asList(tokens));
}
/**
* Convert a {@link Collection} to a delimited {@code String} (e.g. CSV).
* <p>Useful for {@code toString()} implementations.
* @param coll the {@code Collection} to convert (potentially {@code null} or empty)
* @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(
@Nullable Collection<?> coll, String delim, String prefix, String suffix) {
if (CollectionUtils.isEmpty(coll)) {
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).
* <p>Useful for {@code toString()} implementations.
* @param coll the {@code Collection} to convert (potentially {@code null} or empty)
* @param delim the delimiter to use (typically a ",")
* @return the delimited {@code String}
*/
public static String collectionToDelimitedString(@Nullable Collection<?> coll, String delim) {
return collectionToDelimitedString(coll, delim, "", "");
}
/**
* Convert a {@code Collection} into a delimited {@code String} (e.g., CSV).
* <p>Useful for {@code toString()} implementations.
* @param coll the {@code Collection} to convert (potentially {@code null} or empty)
* @return the delimited {@code String}
*/
public static String collectionToCommaDelimitedString(@Nullable Collection<?> coll) {
return collectionToDelimitedString(coll, ",");
}
/**
* Convert a {@code String} array into a delimited {@code String} (e.g. CSV).
* <p>Useful for {@code toString()} implementations.
* @param arr the array to display (potentially {@code null} or empty)
* @param delim the delimiter to use (typically a ",")
* @return the delimited {@code String}
*/
public static String arrayToDelimitedString(@Nullable Object[] arr, String delim) {
if (ObjectUtils.isEmpty(arr)) {
return "";
}
if (arr.length == 1) {
return ObjectUtils.nullSafeToString(arr[0]);
}
StringJoiner sj = new StringJoiner(delim);
for (Object o : arr) {
sj.add(String.valueOf(o));
}
return sj.toString();
}
/**
* Convert a {@code String} array into a comma delimited {@code String}
* (i.e., CSV).
* <p>Useful for {@code toString()} implementations.
* @param arr the array to display (potentially {@code null} or empty)
* @return the delimited {@code String}
*/
public static String arrayToCommaDelimitedString(@Nullable Object[] arr) {
return arrayToDelimitedString(arr, ",");
}
}
