Class Strings
- java.lang.Object
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- org.apache.logging.log4j.util.Strings
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public final class Strings extends Object
Consider this class private.- See Also:
- Apache Commons Lang
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Field Summary
Fields Modifier and Type Field Description static String
EMPTY
The empty string.static String[]
EMPTY_ARRAY
The empty array.static String
LINE_SEPARATOR
OS-dependent line separator, defaults to"\n"
if the system property""line.separator"
cannot be read.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static String
concat(String str1, String str2)
Concatenates 2 Strings without allocation.static String
dquote(String str)
Returns a double quoted string.static boolean
isBlank(String s)
Checks if a String is blank.static boolean
isEmpty(CharSequence cs)
Checks if a CharSequence is empty ("") or null.static boolean
isNotBlank(String s)
Checks if a String is not blank.static boolean
isNotEmpty(CharSequence cs)
Checks if a CharSequence is not empty ("") and not null.static String
join(Iterable<?> iterable, char separator)
Joins the elements of the providedIterable
into a single String containing the provided elements.static String
join(Iterator<?> iterator, char separator)
Joins the elements of the providedIterator
into a single String containing the provided elements.static String
left(String str, int len)
Gets the leftmostlen
characters of a String.static String
quote(String str)
Returns a quoted string.static String
repeat(String str, int count)
Creates a new string repeating givenstr
count
times.static String[]
splitList(String string)
static String
toRootLowerCase(String str)
Shorthand forstr.toLowerCase(Locale.ROOT);
static String
toRootUpperCase(String str)
Shorthand forstr.toUpperCase(Locale.ROOT);
static String
trimToNull(String str)
Removes control characters (char <= 32) from both ends of this String returningnull
if the String is empty ("") after the trim or if it isnull
.
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Field Detail
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EMPTY
public static final String EMPTY
The empty string.- See Also:
- Constant Field Values
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EMPTY_ARRAY
public static final String[] EMPTY_ARRAY
The empty array.
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LINE_SEPARATOR
public static final String LINE_SEPARATOR
OS-dependent line separator, defaults to"\n"
if the system property""line.separator"
cannot be read.
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Method Detail
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dquote
public static String dquote(String str)
Returns a double quoted string.- Parameters:
str
- a String- Returns:
"str"
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isBlank
public static boolean isBlank(String s)
Checks if a String is blank. A blank string is one that is eithernull
, empty, or all characters areCharacter.isWhitespace(char)
.- Parameters:
s
- the String to check, may benull
- Returns:
true
if the String isnull
, empty, or or all characters areCharacter.isWhitespace(char)
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isEmpty
public static boolean isEmpty(CharSequence cs)
Checks if a CharSequence is empty ("") or null.
Strings.isEmpty(null) = true Strings.isEmpty("") = true Strings.isEmpty(" ") = false Strings.isEmpty("bob") = false Strings.isEmpty(" bob ") = false
NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is available in isBlank().
Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.isEmpty(CharSequence)
- Parameters:
cs
- the CharSequence to check, may be null- Returns:
true
if the CharSequence is empty or null
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isNotBlank
public static boolean isNotBlank(String s)
Checks if a String is not blank. The opposite ofisBlank(String)
.- Parameters:
s
- the String to check, may benull
- Returns:
true
if the String is non-null
and has content after being trimmed.
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isNotEmpty
public static boolean isNotEmpty(CharSequence cs)
Checks if a CharSequence is not empty ("") and not null.
Strings.isNotEmpty(null) = false Strings.isNotEmpty("") = false Strings.isNotEmpty(" ") = true Strings.isNotEmpty("bob") = true Strings.isNotEmpty(" bob ") = true
Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.isNotEmpty(CharSequence)
- Parameters:
cs
- the CharSequence to check, may be null- Returns:
true
if the CharSequence is not empty and not null
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join
public static String join(Iterable<?> iterable, char separator)
Joins the elements of the provided
Iterable
into a single String containing the provided elements.No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.
- Parameters:
iterable
- theIterable
providing the values to join together, may be nullseparator
- the separator character to use- Returns:
- the joined String,
null
if null iterator input
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join
public static String join(Iterator<?> iterator, char separator)
Joins the elements of the provided
Iterator
into a single String containing the provided elements.No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.
- Parameters:
iterator
- theIterator
of values to join together, may be nullseparator
- the separator character to use- Returns:
- the joined String,
null
if null iterator input
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left
public static String left(String str, int len)
Gets the leftmost
len
characters of a String.If
len
characters are not available, or the String isnull
, the String will be returned without an exception. An empty String is returned if len is negative.StringUtils.left(null, *) = null StringUtils.left(*, -ve) = "" StringUtils.left("", *) = "" StringUtils.left("abc", 0) = "" StringUtils.left("abc", 2) = "ab" StringUtils.left("abc", 4) = "abc"
Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.
- Parameters:
str
- the String to get the leftmost characters from, may be nulllen
- the length of the required String- Returns:
- the leftmost characters,
null
if null String input
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quote
public static String quote(String str)
Returns a quoted string.- Parameters:
str
- a String- Returns:
'str'
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trimToNull
public static String trimToNull(String str)
Removes control characters (char <= 32) from both ends of this String returning
null
if the String is empty ("") after the trim or if it isnull
.The String is trimmed using
String.trim()
. Trim removes start and end characters <= 32.Strings.trimToNull(null) = null Strings.trimToNull("") = null Strings.trimToNull(" ") = null Strings.trimToNull("abc") = "abc" Strings.trimToNull(" abc ") = "abc"
Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.trimToNull(String)
- Parameters:
str
- the String to be trimmed, may be null- Returns:
- the trimmed String,
null
if only chars <= 32, empty or null String input
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toRootLowerCase
public static String toRootLowerCase(String str)
Shorthand forstr.toLowerCase(Locale.ROOT);
- Parameters:
str
- The string to upper case.- Returns:
- a new string
- See Also:
String.toLowerCase(Locale)
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toRootUpperCase
public static String toRootUpperCase(String str)
Shorthand forstr.toUpperCase(Locale.ROOT);
- Parameters:
str
- The string to lower case.- Returns:
- a new string
- See Also:
String.toLowerCase(Locale)
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concat
public static String concat(String str1, String str2)
Concatenates 2 Strings without allocation.- Parameters:
str1
- the first string.str2
- the second string.- Returns:
- the concatenated String.
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repeat
public static String repeat(String str, int count)
Creates a new string repeating givenstr
count
times.- Parameters:
str
- input stringcount
- the repetition count- Returns:
- the new string
- Throws:
IllegalArgumentException
- if eitherstr
is null orcount
is negative
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