Class StringUtil

java.lang.Object

io.netty.util.internal.StringUtil

public final class StringUtil
extends java.lang.Object

String utility class.

Field Summary

Fields

Modifier and Type	Field	Description
private static final java.lang.String[]	BYTE2HEX_NOPAD
private static final java.lang.String[]	BYTE2HEX_PAD
static final char	CARRIAGE_RETURN
static final char	COMMA
private static final int	CSV_NUMBER_ESCAPE_CHARACTERS	2 - Quote character at beginning and end.
static final char	DOUBLE_QUOTE
static final java.lang.String	EMPTY_STRING
private static final byte[]	HEX2B
static final char	LINE_FEED
static final java.lang.String	NEWLINE
private static final char	PACKAGE_SEPARATOR_CHAR
static final char	SPACE
static final char	TAB

Constructor Summary

Constructors

Modifier	Constructor	Description
private	StringUtil()

Method Summary

Modifier and Type	Method	Description
static java.lang.String	byteToHexString(int value)	Converts the specified byte value into a hexadecimal integer.
static <T extends java.lang.Appendable> T	byteToHexString(T buf, int value)	Converts the specified byte value into a hexadecimal integer and appends it to the specified buffer.
static java.lang.String	byteToHexStringPadded(int value)	Converts the specified byte value into a 2-digit hexadecimal integer.
static <T extends java.lang.Appendable> T	byteToHexStringPadded(T buf, int value)	Converts the specified byte value into a 2-digit hexadecimal integer and appends it to the specified buffer.
static java.lang.String	className(java.lang.Object o)	Generates a class name from a Class.
static boolean	commonSuffixOfLength(java.lang.String s, java.lang.String p, int len)	Checks if two strings have the same suffix of specified length
static byte	decodeHexByte(java.lang.CharSequence s, int pos)	Decode a 2-digit hex byte from within a string.
static byte[]	decodeHexDump(java.lang.CharSequence hexDump)	Decodes a hex dump
static byte[]	decodeHexDump(java.lang.CharSequence hexDump, int fromIndex, int length)	Decodes part of a string with hex dump
static int	decodeHexNibble(byte b)	Helper to decode half of a hexadecimal number from a string.
static int	decodeHexNibble(char c)	Helper to decode half of a hexadecimal number from a string.
static boolean	endsWith(java.lang.CharSequence s, char c)	Determine if the string s ends with the char c.
static java.lang.CharSequence	escapeCsv(java.lang.CharSequence value)	Escapes the specified value, if necessary according to RFC-4180.
static java.lang.CharSequence	escapeCsv(java.lang.CharSequence value, boolean trimWhiteSpace)	Escapes the specified value, if necessary according to RFC-4180.
private static int	indexOfFirstNonOwsChar(java.lang.CharSequence value, int length)
private static int	indexOfLastNonOwsChar(java.lang.CharSequence value, int start, int length)
static int	indexOfNonWhiteSpace(java.lang.CharSequence seq, int offset)	Find the index of the first non-white space character in s starting at offset.
static int	indexOfWhiteSpace(java.lang.CharSequence seq, int offset)	Find the index of the first white space character in s starting at offset.
private static boolean	isDoubleQuote(char c)
static boolean	isNullOrEmpty(java.lang.String s)	Determine if a string is null or String.isEmpty() returns true.
private static boolean	isOws(char c)
static boolean	isSurrogate(char c)	Determine if c lies within the range of values defined for Surrogate Code Point.
static java.lang.CharSequence	join(java.lang.CharSequence separator, java.lang.Iterable<? extends java.lang.CharSequence> elements)	Returns a char sequence that contains all elements joined by a given separator.
static int	length(java.lang.String s)	Get the length of a string, null input is considered 0 length.
private static java.lang.IllegalArgumentException	newInvalidEscapedCsvFieldException(java.lang.CharSequence value, int index)
static java.lang.String	simpleClassName(java.lang.Class<?> clazz)	Generates a simplified name from a Class.
static java.lang.String	simpleClassName(java.lang.Object o)	The shortcut to simpleClassName(o.getClass()).
static java.lang.String	substringAfter(java.lang.String value, char delim)	Get the item after one char delim if the delim is found (else null).
static java.lang.String	substringBefore(java.lang.String value, char delim)	Get the item before one char delim if the delim is found (else null).
static java.lang.String	toHexString(byte[] src)	Converts the specified byte array into a hexadecimal value.
static java.lang.String	toHexString(byte[] src, int offset, int length)	Converts the specified byte array into a hexadecimal value.
static <T extends java.lang.Appendable> T	toHexString(T dst, byte[] src)	Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.
static <T extends java.lang.Appendable> T	toHexString(T dst, byte[] src, int offset, int length)	Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.
static java.lang.String	toHexStringPadded(byte[] src)	Converts the specified byte array into a hexadecimal value.
static java.lang.String	toHexStringPadded(byte[] src, int offset, int length)	Converts the specified byte array into a hexadecimal value.
static <T extends java.lang.Appendable> T	toHexStringPadded(T dst, byte[] src)	Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.
static <T extends java.lang.Appendable> T	toHexStringPadded(T dst, byte[] src, int offset, int length)	Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.
static java.lang.CharSequence	trimOws(java.lang.CharSequence value)	Trim optional white-space characters from the specified value, according to RFC-7230.
static java.lang.CharSequence	unescapeCsv(java.lang.CharSequence value)	Unescapes the specified escaped CSV field, if necessary according to RFC-4180.
static java.util.List<java.lang.CharSequence>	unescapeCsvFields(java.lang.CharSequence value)	Unescapes the specified escaped CSV fields according to RFC-4180.
private static void	validateCsvFormat(java.lang.CharSequence value)	Validate if value is a valid csv field without double-quotes.

Methods inherited from class java.lang.Object

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

Field Details

EMPTY_STRING

public static final java.lang.String EMPTY_STRING

See Also:

• Constant Field Values

NEWLINE

public static final java.lang.String NEWLINE

DOUBLE_QUOTE

public static final char DOUBLE_QUOTE

See Also:

• Constant Field Values

COMMA

public static final char COMMA

See Also:

• Constant Field Values

LINE_FEED

public static final char LINE_FEED

See Also:

• Constant Field Values

CARRIAGE_RETURN

public static final char CARRIAGE_RETURN

See Also:

• Constant Field Values

TAB

public static final char TAB

See Also:

• Constant Field Values

SPACE

public static final char SPACE

See Also:

• Constant Field Values

BYTE2HEX_PAD

private static final java.lang.String[] BYTE2HEX_PAD

BYTE2HEX_NOPAD

private static final java.lang.String[] BYTE2HEX_NOPAD

HEX2B

private static final byte[] HEX2B

CSV_NUMBER_ESCAPE_CHARACTERS

private static final int CSV_NUMBER_ESCAPE_CHARACTERS

2 - Quote character at beginning and end. 5 - Extra allowance for anticipated escape characters that may be added.

See Also:

• Constant Field Values

PACKAGE_SEPARATOR_CHAR

private static final char PACKAGE_SEPARATOR_CHAR

See Also:

• Constant Field Values

Constructor Details

StringUtil

private StringUtil()

Method Details

substringAfter

public static java.lang.String substringAfter(java.lang.String value,
 char delim)

Get the item after one char delim if the delim is found (else null). This operation is a simplified and optimized version of String.split(String, int).

substringBefore

public static java.lang.String substringBefore(java.lang.String value,
 char delim)

Get the item before one char delim if the delim is found (else null). This operation is a simplified and optimized version of String.split(String, int).

commonSuffixOfLength

public static boolean commonSuffixOfLength(java.lang.String s,
 java.lang.String p,
 int len)

Checks if two strings have the same suffix of specified length

Parameters:

s - string

p - string

len - length of the common suffix

Returns:

true if both s and p are not null and both have the same suffix. Otherwise - false

byteToHexStringPadded

public static java.lang.String byteToHexStringPadded(int value)

Converts the specified byte value into a 2-digit hexadecimal integer.

byteToHexStringPadded

public static <T extends java.lang.Appendable> T byteToHexStringPadded(T buf,
 int value)

Converts the specified byte value into a 2-digit hexadecimal integer and appends it to the specified buffer.

toHexStringPadded

public static java.lang.String toHexStringPadded(byte[] src)

Converts the specified byte array into a hexadecimal value.

toHexStringPadded

public static java.lang.String toHexStringPadded(byte[] src,
 int offset,
 int length)

Converts the specified byte array into a hexadecimal value.

toHexStringPadded

public static <T extends java.lang.Appendable> T toHexStringPadded(T dst,
 byte[] src)

Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.

toHexStringPadded

public static <T extends java.lang.Appendable> T toHexStringPadded(T dst,
 byte[] src,
 int offset,
 int length)

Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.

byteToHexString

public static java.lang.String byteToHexString(int value)

Converts the specified byte value into a hexadecimal integer.

byteToHexString

public static <T extends java.lang.Appendable> T byteToHexString(T buf,
 int value)

Converts the specified byte value into a hexadecimal integer and appends it to the specified buffer.

toHexString

public static java.lang.String toHexString(byte[] src)

Converts the specified byte array into a hexadecimal value.

toHexString

public static java.lang.String toHexString(byte[] src,
 int offset,
 int length)

Converts the specified byte array into a hexadecimal value.

toHexString

public static <T extends java.lang.Appendable> T toHexString(T dst,
 byte[] src)

Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.

toHexString

public static <T extends java.lang.Appendable> T toHexString(T dst,
 byte[] src,
 int offset,
 int length)

Converts the specified byte array into a hexadecimal value and appends it to the specified buffer.

decodeHexNibble

public static int decodeHexNibble(char c)

Helper to decode half of a hexadecimal number from a string.

Parameters:

c - The ASCII character of the hexadecimal number to decode. Must be in the range [0-9a-fA-F].

Returns:

The hexadecimal value represented in the ASCII character given, or -1 if the character is invalid.

decodeHexNibble

public static int decodeHexNibble(byte b)

Helper to decode half of a hexadecimal number from a string.

Parameters:

b - The ASCII character of the hexadecimal number to decode. Must be in the range [0-9a-fA-F].

Returns:

The hexadecimal value represented in the ASCII character given, or -1 if the character is invalid.

decodeHexByte

public static byte decodeHexByte(java.lang.CharSequence s,
 int pos)

Decode a 2-digit hex byte from within a string.

decodeHexDump

public static byte[] decodeHexDump(java.lang.CharSequence hexDump,
 int fromIndex,
 int length)

Decodes part of a string with hex dump

Parameters:

hexDump - a CharSequence which contains the hex dump

fromIndex - start of hex dump in hexDump

length - hex string length

decodeHexDump

public static byte[] decodeHexDump(java.lang.CharSequence hexDump)

Decodes a hex dump

className

public static java.lang.String className(java.lang.Object o)

Generates a class name from a Class. Similar to Class.getName(), but null-safe.

simpleClassName

public static java.lang.String simpleClassName(java.lang.Object o)

The shortcut to simpleClassName(o.getClass()).

simpleClassName

public static java.lang.String simpleClassName(java.lang.Class<?> clazz)

Generates a simplified name from a Class. Similar to Class.getSimpleName(), but it works fine with anonymous classes.

escapeCsv

public static java.lang.CharSequence escapeCsv(java.lang.CharSequence value)

Escapes the specified value, if necessary according to RFC-4180.

Parameters:

value - The value which will be escaped according to RFC-4180

Returns:

CharSequence the escaped value if necessary, or the value unchanged

escapeCsv

public static java.lang.CharSequence escapeCsv(java.lang.CharSequence value,
 boolean trimWhiteSpace)

Escapes the specified value, if necessary according to RFC-4180.

Parameters:

value - The value which will be escaped according to RFC-4180

trimWhiteSpace - The value will first be trimmed of its optional white-space characters, according to RFC-7230

Returns:

CharSequence the escaped value if necessary, or the value unchanged

unescapeCsv

public static java.lang.CharSequence unescapeCsv(java.lang.CharSequence value)

Unescapes the specified escaped CSV field, if necessary according to RFC-4180.

Parameters:

value - The escaped CSV field which will be unescaped according to RFC-4180

Returns:

CharSequence the unescaped value if necessary, or the value unchanged

unescapeCsvFields

public static java.util.List<java.lang.CharSequence> unescapeCsvFields(java.lang.CharSequence value)

Unescapes the specified escaped CSV fields according to RFC-4180.

Parameters:

value - A string with multiple CSV escaped fields which will be unescaped according to RFC-4180

Returns:

List the list of unescaped fields

validateCsvFormat

private static void validateCsvFormat(java.lang.CharSequence value)

Validate if value is a valid csv field without double-quotes.

Throws:

java.lang.IllegalArgumentException - if value needs to be encoded with double-quotes.

newInvalidEscapedCsvFieldException

private static java.lang.IllegalArgumentException newInvalidEscapedCsvFieldException(java.lang.CharSequence value,
 int index)

length

public static int length(java.lang.String s)

Get the length of a string, null input is considered 0 length.

isNullOrEmpty

public static boolean isNullOrEmpty(java.lang.String s)

Determine if a string is null or String.isEmpty() returns true.

indexOfNonWhiteSpace

public static int indexOfNonWhiteSpace(java.lang.CharSequence seq,
 int offset)

Find the index of the first non-white space character in s starting at offset.

Parameters:

seq - The string to search.

offset - The offset to start searching at.

Returns:

the index of the first non-white space character or <-1 if none was found.

indexOfWhiteSpace

public static int indexOfWhiteSpace(java.lang.CharSequence seq,
 int offset)

Find the index of the first white space character in s starting at offset.

Parameters:

seq - The string to search.

offset - The offset to start searching at.

Returns:

the index of the first white space character or <-1 if none was found.

isSurrogate

public static boolean isSurrogate(char c)

Determine if c lies within the range of values defined for Surrogate Code Point.

Parameters:

c - the character to check.

Returns:

true if c lies within the range of values defined for Surrogate Code Point. false otherwise.

isDoubleQuote

private static boolean isDoubleQuote(char c)

endsWith

public static boolean endsWith(java.lang.CharSequence s,
 char c)

Determine if the string s ends with the char c.

Parameters:

s - the string to test

c - the tested char

Returns:

true if s ends with the char c

trimOws

public static java.lang.CharSequence trimOws(java.lang.CharSequence value)

Trim optional white-space characters from the specified value, according to RFC-7230.

Parameters:

value - the value to trim

Returns:

CharSequence the trimmed value if necessary, or the value unchanged

join

public static java.lang.CharSequence join(java.lang.CharSequence separator,
 java.lang.Iterable<? extends java.lang.CharSequence> elements)

Returns a char sequence that contains all elements joined by a given separator.

Parameters:

separator - for each element

elements - to join together

Returns:

a char sequence joined by a given separator.

indexOfFirstNonOwsChar

private static int indexOfFirstNonOwsChar(java.lang.CharSequence value,
 int length)

Returns:

length if no OWS is found.

indexOfLastNonOwsChar

private static int indexOfLastNonOwsChar(java.lang.CharSequence value,
 int start,
 int length)

Returns:

start if no OWS is found.

isOws

private static boolean isOws(char c)