Package org.jivesoftware.smack.util

Class StringUtils

java.lang.Object

org.jivesoftware.smack.util.StringUtils

public class StringUtils
extends Object

A collection of utility methods for String objects.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	AMP_ENCODE
static final String	APOS_ENCODE
static final String	GT_ENCODE
static final char[]	HEX_CHARS
static final String	LT_ENCODE
static final String	MD5
static final String	PORTABLE_NEWLINE_REGEX
static final String	QUOTE_ENCODE
static final String	SHA1
static final String	UNAMBIGUOUS_NUMBERS_AND_LETTERS_STRING	24 upper case characters from the latin alphabet and numbers without '0' and 'O'.

Constructor Summary

Constructors

Constructor	Description
StringUtils()

Method Summary

Modifier and Type	Method	Description
static Appendable	appendHeading(Appendable appendable, String heading)
static Appendable	appendHeading(Appendable appendable, String heading, char underlineChar)
static void	appendTo(Collection<? extends Object> collection, StringBuilder sb)
static void	appendTo(Collection<? extends Object> collection, String delimiter, StringBuilder sb)
static <O> void	appendTo(Collection<O> collection, StringBuilder sb, Consumer<O> appendFunction)
static <O> void	appendTo(Collection<O> collection, String delimiter, StringBuilder sb, Consumer<O> appendFunction)
static String	collectionToString(Collection<? extends Object> collection)	Transform a collection of objects to a whitespace delimited String.
static String	deleteXmlWhitespace(String string)
static String	encodeHex(byte[] bytes)	Encodes an array of bytes as String representation of hexadecimal.
static CharSequence	escapeForXml(CharSequence input)	Escape input for XML.
static CharSequence	escapeForXmlAttribute(CharSequence input)	Escape input for XML.
static CharSequence	escapeForXmlAttributeApos(CharSequence input)	Escape input for XML.
static CharSequence	escapeForXmlText(CharSequence input)	Escape input for XML.
static String	hash(String data)	Deprecated. use SHA1.hex(String) instead.
static String	insecureRandomString(int length)	Returns a random String of numbers and letters (lower and upper case) of the specified length.
static boolean	isEmpty(CharSequence cs)	Returns true if the given CharSequence is empty.
static boolean	isNotEmpty(CharSequence cs)	Returns true if CharSequence is not null and is not empty, false otherwise.
static boolean	isNotEmpty(CharSequence... css)	Returns true if all given CharSequences are not empty.
static boolean	isNullOrEmpty(CharSequence cs)	Returns true if the given CharSequence is null or empty.
static boolean	isNullOrEmpty(CharSequence... css)	Returns true if all given CharSequences are either null or empty.
static boolean	isNullOrNotEmpty(CharSequence cs)
static String	maybeToString(CharSequence cs)	Return the String representation of the given char sequence if it is not null.
static int	nullSafeCharSequenceComparator(CharSequence csOne, CharSequence csTwo)
static boolean	nullSafeCharSequenceEquals(CharSequence csOne, CharSequence csTwo)
static String	randomString(int length)
static String	randomString(int length, Random random)
static <CS extends CharSequence> CS	requireNotNullNorEmpty(CS cs, String message)	Require a CharSequence to be neither null, nor empty.
static <CS extends CharSequence> CS	requireNotNullOrEmpty(CS cs, String message)	Deprecated. use requireNotNullNorEmpty(CharSequence, String) instead.
static <CS extends CharSequence> CS	requireNullOrNotEmpty(CS cs, String message)
static String	returnIfNotEmptyTrimmed(String string)
static String	secureOfflineAttackSafeRandomString()	Generate a secure random string with is human readable.
static String	secureOnlineAttackSafeRandomString()
static String	secureUniqueRandomString()
static List<String>	splitLinesPortable(String input)
static StringBuilder	toStringBuilder(Collection<? extends Object> collection, String delimiter)	Transform a collection of objects to a delimited String.
static List<String>	toStrings(Collection<? extends CharSequence> charSequences)
static byte[]	toUtf8Bytes(String string)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

MD5

public static final String MD5

See Also:

• Constant Field Values

SHA1

public static final String SHA1

See Also:

• Constant Field Values

QUOTE_ENCODE

public static final String QUOTE_ENCODE

See Also:

• Constant Field Values

APOS_ENCODE

public static final String APOS_ENCODE

See Also:

• Constant Field Values

AMP_ENCODE

public static final String AMP_ENCODE

See Also:

• Constant Field Values

LT_ENCODE

public static final String LT_ENCODE

See Also:

• Constant Field Values

GT_ENCODE

public static final String GT_ENCODE

See Also:

• Constant Field Values

HEX_CHARS

public static final char[] HEX_CHARS

UNAMBIGUOUS_NUMBERS_AND_LETTERS_STRING

public static final String UNAMBIGUOUS_NUMBERS_AND_LETTERS_STRING

24 upper case characters from the latin alphabet and numbers without '0' and 'O'.

See Also:

• Constant Field Values

PORTABLE_NEWLINE_REGEX

public static final String PORTABLE_NEWLINE_REGEX

See Also:

• Constant Field Values

Constructor Details

StringUtils

public StringUtils()

Method Details

escapeForXml

public static CharSequence escapeForXml(CharSequence input)

Escape input for XML.

Parameters:

input - the input to escape.

Returns:

the XML escaped variant of input.

escapeForXmlAttribute

public static CharSequence escapeForXmlAttribute(CharSequence input)

Escape input for XML.

Parameters:

input - the input to escape.

Returns:

the XML escaped variant of input.

Since:

4.2

escapeForXmlAttributeApos

public static CharSequence escapeForXmlAttributeApos(CharSequence input)

Escape input for XML.

This is an optimized variant of escapeForXmlAttribute(CharSequence) for XML where the XML attribute is quoted using ''' (Apos).

Parameters:

input - the input to escape.

Returns:

the XML escaped variant of input.

Since:

4.2

escapeForXmlText

public static CharSequence escapeForXmlText(CharSequence input)

Escape input for XML.

Parameters:

input - the input to escape.

Returns:

the XML escaped variant of input.

Since:

4.2

hash

@Deprecated
public static String hash(String data)

Deprecated.

use SHA1.hex(String) instead.

Hashes a String using the SHA-1 algorithm and returns the result as a String of hexadecimal numbers. This method is synchronized to avoid excessive MessageDigest object creation. If calling this method becomes a bottleneck in your code, you may wish to maintain a pool of MessageDigest objects instead of using this method.

A hash is a one-way function -- that is, given an input, an output is easily computed. However, given the output, the input is almost impossible to compute. This is useful for passwords since we can store the hash and a hacker will then have a very hard time determining the original password.

Parameters:

data - the String to compute the hash of.

Returns:

a hashed version of the passed-in String

encodeHex

public static String encodeHex(byte[] bytes)

Encodes an array of bytes as String representation of hexadecimal.

Parameters:

bytes - an array of bytes to convert to a hex string.

Returns:

generated hex string.

toUtf8Bytes

public static byte[] toUtf8Bytes(String string)

insecureRandomString

public static String insecureRandomString(int length)

Returns a random String of numbers and letters (lower and upper case) of the specified length. The method uses the Random class that is built-in to Java which is suitable for low to medium grade security uses. This means that the output is only pseudo random, i.e., each number is mathematically generated so is not truly random.

The specified length must be at least one. If not, the method will return null.

Parameters:

length - the desired length of the random String to return.

Returns:

a random String of numbers and letters of the specified length.

secureOnlineAttackSafeRandomString

public static String secureOnlineAttackSafeRandomString()

secureUniqueRandomString

public static String secureUniqueRandomString()

secureOfflineAttackSafeRandomString

public static String secureOfflineAttackSafeRandomString()

Generate a secure random string with is human readable. The resulting string consists of 24 upper case characters from the Latin alphabet and numbers without '0' and 'O', grouped into 4-characters chunks, e.g. "TWNK-KD5Y-MT3T-E1GS-DRDB-KVTW". The characters are randomly selected by a cryptographically secure pseudorandom number generator (CSPRNG).

The string can be used a backup "code" for secrets, and is in fact the same as the one backup code specified in XEP-0373 and the one used by the Backup Format v2 of OpenKeychain.

Returns:

a human readable secure random string.

See Also:

• XEP-0373 §5.4 Encrypting the Secret Key Backup

randomString

public static String randomString(int length)

randomString

public static String randomString(int length,
 Random random)

isNotEmpty

public static boolean isNotEmpty(CharSequence cs)

Returns true if CharSequence is not null and is not empty, false otherwise. Examples: isNotEmpty(null) - false isNotEmpty("") - false isNotEmpty(" ") - true isNotEmpty("empty") - true

Parameters:

cs - checked CharSequence

Returns:

true if string is not null and is not empty, false otherwise

isNullOrEmpty

public static boolean isNullOrEmpty(CharSequence cs)

Returns true if the given CharSequence is null or empty.

Parameters:

cs - TODO javadoc me please

Returns:

true if the given CharSequence is null or empty

isNotEmpty

public static boolean isNotEmpty(CharSequence... css)

Returns true if all given CharSequences are not empty.

Parameters:

css - the CharSequences to test.

Returns:

true if all given CharSequences are not empty.

isNullOrEmpty

public static boolean isNullOrEmpty(CharSequence... css)

Returns true if all given CharSequences are either null or empty.

Parameters:

css - the CharSequences to test.

Returns:

true if all given CharSequences are null or empty.

isNullOrNotEmpty

public static boolean isNullOrNotEmpty(CharSequence cs)

isEmpty

public static boolean isEmpty(CharSequence cs)

Returns true if the given CharSequence is empty.

Parameters:

cs - TODO javadoc me please

Returns:

true if the given CharSequence is empty

collectionToString

public static String collectionToString(Collection<? extends Object> collection)

Transform a collection of objects to a whitespace delimited String.

Parameters:

collection - the collection to transform.

Returns:

a String with all the elements of the collection.

toStringBuilder

public static StringBuilder toStringBuilder(Collection<? extends Object> collection,
 String delimiter)

Transform a collection of objects to a delimited String.

Parameters:

collection - the collection to transform.

delimiter - the delimiter used to delimit the Strings.

Returns:

a StringBuilder with all the elements of the collection.

appendTo

public static void appendTo(Collection<? extends Object> collection,
 StringBuilder sb)

appendTo

public static <O> void appendTo(Collection<O> collection,
 StringBuilder sb,
 Consumer<O> appendFunction)

appendTo

public static void appendTo(Collection<? extends Object> collection,
 String delimiter,
 StringBuilder sb)

appendTo

public static <O> void appendTo(Collection<O> collection,
 String delimiter,
 StringBuilder sb,
 Consumer<O> appendFunction)

returnIfNotEmptyTrimmed

public static String returnIfNotEmptyTrimmed(String string)

nullSafeCharSequenceEquals

public static boolean nullSafeCharSequenceEquals(CharSequence csOne,
 CharSequence csTwo)

nullSafeCharSequenceComparator

public static int nullSafeCharSequenceComparator(CharSequence csOne,
 CharSequence csTwo)

requireNotNullOrEmpty

@Deprecated
public static <CS extends CharSequence> CS requireNotNullOrEmpty(CS cs,
 String message)

Deprecated.

use requireNotNullNorEmpty(CharSequence, String) instead.

Require a CharSequence to be neither null, nor empty.

Type Parameters:

CS - CharSequence type

Parameters:

cs - CharSequence

message - error message

Returns:

cs TODO javadoc me please

requireNotNullNorEmpty

public static <CS extends CharSequence> CS requireNotNullNorEmpty(CS cs,
 String message)

Require a CharSequence to be neither null, nor empty.

Type Parameters:

CS - CharSequence type

Parameters:

cs - CharSequence

message - error message

Returns:

cs TODO javadoc me please

requireNullOrNotEmpty

public static <CS extends CharSequence> CS requireNullOrNotEmpty(CS cs,
 String message)

maybeToString

public static String maybeToString(CharSequence cs)

Return the String representation of the given char sequence if it is not null.

Parameters:

cs - the char sequence or null.

Returns:

the String representation of cs or null.

deleteXmlWhitespace

public static String deleteXmlWhitespace(String string)

appendHeading

public static Appendable appendHeading(Appendable appendable,
 String heading)
                                throws IOException

Throws:

IOException

appendHeading

public static Appendable appendHeading(Appendable appendable,
 String heading,
 char underlineChar)
                                throws IOException

Throws:

IOException

splitLinesPortable

public static List<String> splitLinesPortable(String input)

toStrings

public static List<String> toStrings(Collection<? extends CharSequence> charSequences)