org.kocakosm.pitaya.util

Class Strings

java.lang.Object

org.kocakosm.pitaya.util.Strings

public final class Strings
extends Object

String utilities.

Author:

Osman KOCAK

Method Summary

Methods

Modifier and Type	Method and Description
static String	abbreviate(String str, int length) Abbreviates the given String using "..." so that the returned String's length is equal to length.
static String	abbreviate(String str, int length, String ellipsis) Abbreviates the given String using the specified ellipsis so that the returned String's length is equal to length.
static String	concat(String... strings) Concatenates the given Strings.
static int	countOccurrences(String str, String sub) Counts the occurrences of the substring sub in str.
static int	distance(String str1, String str2) Computes and returns the Damerau-Levenshtein distance between the given Strings.
static String	emptyToNull(String str) Returns null if the given String is empty, returns the (unmodified) parameter otherwise.
static boolean	isBlank(String str) Returns whether the given String only contains space, '\n', '\r' or '\t' characters.
static boolean	isNullOrBlank(String str) Returns whether the given String is null or only contains space, '\n', '\r' or '\t' characters.
static boolean	isNullOrEmpty(String str) Returns whether the given String is null or empty.
static boolean	isNullOrWhiteSpace(String str) Returns whether the given String is null or only contains space characters.
static boolean	isWhiteSpace(String str) Returns whether the given String only contains space characters.
static String	nullToEmpty(String str) Returns an empty String if the given one is null, or returns the (unmodified) parameter otherwise.
static String	padLeft(String str, int len, char padChar) Returns a String of length at least len created by prepending as many copies of padChar as necessary to reach that length.
static String	padRight(String str, int len, char padChar) Returns a String of length at least len created by appending as many copies of padChar as necessary to reach that length.
static String	quote(String str) Quotes the given String with double quotes.
static String	random(int length, char... chars) Returns a pseudo-random String of the specified size using characters from the given array.
static String	random(int length, Random rnd, char... chars) Returns a random String using the given characters and the specified source of randomness.
static String	repeat(String str, int count) Returns the String obtained by repeating count times the given String.
static String	reverse(String str) Reverses the given String.
static String	shuffle(String str) Randomly permutes the characters from the given String.
static String	shuffle(String str, Random rnd) Randomly permutes the characters from the given String using the specified source of randomness.
static String	strip(String str, int n) Returns the new String obtained by stripping the first and last n characters from the given one.
static String	stripLeft(String str, int n) Returns the new String obtained by stripping the first n characters from the given one.
static String	stripRight(String str, int n) Returns the new String obtained by stripping the last n characters from the given one.
static String	trim(String str) Returns a copy of the given String with leading and trailing whitespaces omitted.
static String	trimLeft(String str) Returns a copy of the given String with leading whitespaces omitted.
static String	trimRight(String str) Returns a copy of the given String with trailing whitespaces omitted.
static String	unquote(String str) Unquotes the given String, that is, this method removes any leading or trailing double quotes.

Methods inherited from class java.lang.Object

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

Method Detail

isBlank

public static boolean isBlank(String str)

Returns whether the given String only contains space, '\n', '\r' or '\t' characters.

Parameters:

str - the String to test.

Returns:

whether the given String is blank.

Throws:

NullPointerException - if str is null.

isNullOrBlank

public static boolean isNullOrBlank(String str)

Returns whether the given String is null or only contains space, '\n', '\r' or '\t' characters.

Parameters:

str - the String to test.

Returns:

whether the given String is null or blank.

isWhiteSpace

public static boolean isWhiteSpace(String str)

Returns whether the given String only contains space characters.

Parameters:

str - the String to test.

Returns:

whether the given String contains only spaces.

Throws:

NullPointerException - if str is null.

isNullOrWhiteSpace

public static boolean isNullOrWhiteSpace(String str)

Returns whether the given String is null or only contains space characters.

Parameters:

str - the String to test.

Returns:

whether the given String is null or contains only spaces.

isNullOrEmpty

public static boolean isNullOrEmpty(String str)

Returns whether the given String is null or empty.

Parameters:

str - the String to test.

Returns:

true if str is null or empty, false otherwise.

abbreviate

public static String abbreviate(String str,
                int length)

Abbreviates the given String using "..." so that the returned String's length is equal to length.

Parameters:

str - the String to abbreviate.

length - the desired length for the abbreviated String.

Returns:

the abbreviated String.

Throws:

NullPointerException - if str is null.

IllegalArgumentException - if length is too small.

abbreviate

public static String abbreviate(String str,
                int length,
                String ellipsis)

Abbreviates the given String using the specified ellipsis so that the returned String's length is equal to length.

Parameters:

str - the String to abbreviate.

length - the desired length for the abbreviated String.

ellipsis - the ellipsis to use to mark abbreviation.

Returns:

the abbreviated String.

Throws:

NullPointerException - if one of the arguments is null.

IllegalArgumentException - if length is too small.

concat

public static String concat(String... strings)

Concatenates the given Strings.

Parameters:

strings - the Strings to concatenate.

Returns:

the concatenated String.

Throws:

NullPointerException - if strings is null.

distance

public static int distance(String str1,
           String str2)

Computes and returns the Damerau-Levenshtein distance between the given Strings. This distance is obtained by counting the minimum number of operations needed to transform one String into the other, where an operation is defined as an insertion, deletion, or substitution of a single character, or a transposition of two adjacent characters.

Parameters:

str1 - the first String.

str2 - the second String.

Returns:

the distance between str1 and str2.

Throws:

NullPointerException - if one of the arguments is null.

emptyToNull

public static String emptyToNull(String str)

Returns null if the given String is empty, returns the (unmodified) parameter otherwise.

Parameters:

str - the String to test.

Returns:

null if the given String is empty.

nullToEmpty

public static String nullToEmpty(String str)

Returns an empty String if the given one is null, or returns the (unmodified) parameter otherwise.

Parameters:

str - the String to test.

Returns:

an empty String if the given one is null.

random

public static String random(int length,
            char... chars)

Returns a pseudo-random String of the specified size using characters from the given array.

Parameters:

length - the length of the String to produce.

chars - the characters to use to build the String.

Returns:

a pseudo-random String.

Throws:

NullPointerException - if chars is null.

IllegalArgumentException - if length is negative or if chars is empty.

random

public static String random(int length,
            Random rnd,
            char... chars)

Returns a random String using the given characters and the specified source of randomness. All characters have equal likelihood to appear in the resulting String assuming that the source of randomness is fair.

Parameters:

length - the length of the String to produce.

rnd - the source of randomness to use.

chars - the characters to use to build the String.

Returns:

a random String.

Throws:

NullPointerException - if one of the arguments is null.

IllegalArgumentException - if length is negative or if chars is empty.

repeat

public static String repeat(String str,
            int count)

Returns the String obtained by repeating count times the given String.

Parameters:

str - the String to repeat.

count - the number of times the str has to be repeared.

Returns:

the created String.

Throws:

IllegalArgumentException - if count is negative.

NullPointerException - if str is null.

reverse

public static String reverse(String str)

Reverses the given String.

Parameters:

str - the String to reverse.

Returns:

the reversed String.

Throws:

NullPointerException - if str is null.

shuffle

public static String shuffle(String str)

Randomly permutes the characters from the given String. This implementation uses the optimized version of the Fisher-Yates shuffle algorithm (Fisher, Yates, Durstenfeld, Knuth) and thus runs in linear time.

Parameters:

str - the String to be shuffled.

Returns:

the shuffled String.

Throws:

NullPointerException - if str is null.

shuffle

public static String shuffle(String str,
             Random rnd)

Randomly permutes the characters from the given String using the specified source of randomness. All permutations occur with equal likelihood assuming that the source of randomness is fair. This implementation uses the optimized version of the Fisher-Yates shuffle algorithm (Fisher, Yates, Durstenfeld, Knuth) and thus runs in linear time.

Parameters:

str - the String to be shuffled.

rnd - the source of randomness to use.

Returns:

the shuffled String.

Throws:

NullPointerException - if one of the arguments is null.

strip

public static String strip(String str,
           int n)

Returns the new String obtained by stripping the first and last n characters from the given one.

Parameters:

str - the String to be stripped.

n - the number of characters to strip.

Returns:

the stripped String.

Throws:

NullPointerException - if str is null.

IllegalArgumentException - if n is negative.

stripLeft

public static String stripLeft(String str,
               int n)

Returns the new String obtained by stripping the first n characters from the given one.

Parameters:

str - the String to be stripped.

n - the number of characters to strip.

Returns:

the stripped String.

Throws:

NullPointerException - if str is null.

IllegalArgumentException - if n is negative.

stripRight

public static String stripRight(String str,
                int n)

Returns the new String obtained by stripping the last n characters from the given one.

Parameters:

str - the String to be stripped.

n - the number of characters to strip.

Returns:

the stripped String.

Throws:

NullPointerException - if str is null.

IllegalArgumentException - if n is negative.

trim

public static String trim(String str)

Returns a copy of the given String with leading and trailing whitespaces omitted.

Parameters:

str - the String to trim.

Returns:

the trimmed String.

Throws:

NullPointerException - if str is null.

trimLeft

public static String trimLeft(String str)

Returns a copy of the given String with leading whitespaces omitted.

Parameters:

str - the String to trim.

Returns:

the trimmed String.

Throws:

NullPointerException - if str is null.

trimRight

public static String trimRight(String str)

Returns a copy of the given String with trailing whitespaces omitted.

Parameters:

str - the String to trim.

Returns:

the trimmed String.

Throws:

NullPointerException - if str is null.

padLeft

public static String padLeft(String str,
             int len,
             char padChar)

Returns a String of length at least len created by prepending as many copies of padChar as necessary to reach that length.

Parameters:

str - the String to pad.

len - the result's minimum length.

padChar - the padding character.

Returns:

the padded String.

Throws:

IllegalArgumentException - if len is negative.

NullPointerException - if str is null.

padRight

public static String padRight(String str,
              int len,
              char padChar)

Returns a String of length at least len created by appending as many copies of padChar as necessary to reach that length.

Parameters:

str - the String to pad.

len - the result's minimum length.

padChar - the padding character.

Returns:

the padded String.

Throws:

NullPointerException - if str is null.

IllegalArgumentException - if len is negative.

quote

public static String quote(String str)

Quotes the given String with double quotes. If the given String has multiple quotes, only one of them is kept.

Parameters:

str - the String to quote.

Returns:

the quoted String.

Throws:

NullPointerException - if str is null.

unquote

public static String unquote(String str)

Unquotes the given String, that is, this method removes any leading or trailing double quotes. If the given String is not quoted, returns it unmodified.

Parameters:

str - the String to unquote.

Returns:

the unquoted String.

Throws:

NullPointerException - if str is null.

countOccurrences

public static int countOccurrences(String str,
                   String sub)

Counts the occurrences of the substring sub in str.

Parameters:

str - String to search in.

sub - String to search for.

Returns:

the number of occurrences of sub in str.

Throws:

NullPointerException - if one of the arguments is null.