Package com.alibaba.cloud.commons.lang

Class StringUtils

java.lang.Object

com.alibaba.cloud.commons.lang.StringUtils

public final class StringUtils
extends Object

StringUtils. copy from apache common-lang3.

Author:

theonefx

Field Summary

Fields

Modifier and Type	Field	Description
static final String	EMPTY	The empty String "".
static final int	INDEX_NOT_FOUND	Represents a failed index search.

Method Summary

Modifier and Type	Method	Description
static boolean	equals(CharSequence cs1, CharSequence cs2)	Compares two CharSequences, returning true if they represent equal sequences of characters.
static boolean	isBlank(CharSequence cs)	Checks if a CharSequence is whitespace, empty ("") or null.
static boolean	isEmpty(CharSequence cs)	Checks if a CharSequence is empty ("") or null.
static boolean	isNotBlank(CharSequence cs)	Checks if a CharSequence is not empty (""), not null and not whitespace only.
static boolean	isNotEmpty(CharSequence cs)	Checks if a CharSequence is not empty ("") and not null.
static boolean	regionMatches(CharSequence cs, boolean ignoreCase, int thisStart, CharSequence substring, int start, int length)	Green implementation of regionMatches.
static String	substringAfter(String str, String separator)	Gets the substring after the first occurrence of a separator.
static String	substringBetween(String str, String tag)	Gets the String that is nested in between two instances of the same String.
static String	substringBetween(String str, String open, String close)	Gets the String that is nested in between two Strings.
static String	trim(String str)	Removes control characters (char <= 32) from both ends of this String, handling null by returning null.

Methods inherited from class java.lang.Object

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

Field Details

EMPTY

public static final String EMPTY

The empty String "".

Since:

2.0

See Also:

• Constant Field Values

INDEX_NOT_FOUND

public static final int INDEX_NOT_FOUND

Represents a failed index search.

Since:

2.1

See Also:

• Constant Field Values

Method Details

isEmpty

public static boolean isEmpty(CharSequence cs)

Checks if a CharSequence is empty ("") or null.

 StringUtils.isEmpty(null)      = true
 StringUtils.isEmpty("")        = true
 StringUtils.isEmpty(" ")       = false
 StringUtils.isEmpty("bob")     = false
 StringUtils.isEmpty("  bob  ") = false
 

NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is available in isBlank().

Parameters:

cs - the CharSequence to check, may be null

Returns:

true if the CharSequence is empty or null

Since:

3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)

isNotEmpty

public static boolean isNotEmpty(CharSequence cs)

Checks if a CharSequence is not empty ("") and not null.

 StringUtils.isNotEmpty(null)      = false
 StringUtils.isNotEmpty("")        = false
 StringUtils.isNotEmpty(" ")       = true
 StringUtils.isNotEmpty("bob")     = true
 StringUtils.isNotEmpty("  bob  ") = true
 

Parameters:

cs - the CharSequence to check, may be null

Returns:

true if the CharSequence is not empty and not null

Since:

3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)

isBlank

public static boolean isBlank(CharSequence cs)

Checks if a CharSequence is whitespace, empty ("") or null.

 StringUtils.isBlank(null)      = true
 StringUtils.isBlank("")        = true
 StringUtils.isBlank(" ")       = true
 StringUtils.isBlank("bob")     = false
 StringUtils.isBlank("  bob  ") = false
 

Parameters:

cs - the CharSequence to check, may be null

Returns:

true if the CharSequence is null, empty or whitespace

isNotBlank

public static boolean isNotBlank(CharSequence cs)

Checks if a CharSequence is not empty (""), not null and not whitespace only.

Whitespace is defined by Character.isWhitespace(char).

 StringUtils.isNotBlank(null)      = false
 StringUtils.isNotBlank("")        = false
 StringUtils.isNotBlank(" ")       = false
 StringUtils.isNotBlank("bob")     = true
 StringUtils.isNotBlank("  bob  ") = true
 

Parameters:

cs - the CharSequence to check, may be null

Returns:

true if the CharSequence is not empty and not null and not whitespace only

Since:

2.0, 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)

trim

public static String trim(String str)

Removes control characters (char <= 32) from both ends of this String, handling null by returning null.

The String is trimmed using String.trim(). Trim removes start and end characters <= 32.

 StringUtils.trim(null)          = null
 StringUtils.trim("")            = ""
 StringUtils.trim("     ")       = ""
 StringUtils.trim("abc")         = "abc"
 StringUtils.trim("    abc    ") = "abc"
 

Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed string, null if null String input

equals

public static boolean equals(CharSequence cs1,
 CharSequence cs2)

Compares two CharSequences, returning true if they represent equal sequences of characters.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

 StringUtils.equals(null, null)   = true
 StringUtils.equals(null, "abc")  = false
 StringUtils.equals("abc", null)  = false
 StringUtils.equals("abc", "abc") = true
 StringUtils.equals("abc", "ABC") = false
 

Parameters:

cs1 - the first CharSequence, may be null

cs2 - the second CharSequence, may be null

Returns:

true if the CharSequences are equal (case-sensitive), or both null

See Also:

• Object.equals(Object)

regionMatches

public static boolean regionMatches(CharSequence cs,
 boolean ignoreCase,
 int thisStart,
 CharSequence substring,
 int start,
 int length)

Green implementation of regionMatches.

Parameters:

cs - the CharSequence to be processed

ignoreCase - whether or not to be case insensitive

thisStart - the index to start on the cs CharSequence

substring - the CharSequence to be looked for

start - the index to start on the substring CharSequence

length - character length of the region

Returns:

whether the region matched

substringAfter

public static String substringAfter(String str,
 String separator)

Gets the substring after the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the empty string if the input string is not null.

If nothing is found, the empty string is returned.

 StringUtils.substringAfter(null, *)      = null
 StringUtils.substringAfter("", *)        = ""
 StringUtils.substringAfter(*, null)      = ""
 StringUtils.substringAfter("abc", "a")   = "bc"
 StringUtils.substringAfter("abcba", "b") = "cba"
 StringUtils.substringAfter("abc", "c")   = ""
 StringUtils.substringAfter("abc", "d")   = ""
 StringUtils.substringAfter("abc", "")    = "abc"
 

Parameters:

str - the String to get a substring from, may be null

separator - the String to search for, may be null

Returns:

the substring after the first occurrence of the separator, null if null String input

Since:

2.0

substringBetween

public static String substringBetween(String str,
 String tag)

Gets the String that is nested in between two instances of the same String.

A null input String returns null. A null tag returns null.

 StringUtils.substringBetween(null, *)            = null
 StringUtils.substringBetween("", "")             = ""
 StringUtils.substringBetween("", "tag")          = null
 StringUtils.substringBetween("tagabctag", null)  = null
 StringUtils.substringBetween("tagabctag", "")    = ""
 StringUtils.substringBetween("tagabctag", "tag") = "abc"
 

Parameters:

str - the String containing the substring, may be null

tag - the String before and after the substring, may be null

Returns:

the substring, null if no match

Since:

2.0

substringBetween

public static String substringBetween(String str,
 String open,
 String close)

Gets the String that is nested in between two Strings. Only the first match is returned.

A null input String returns null. A null open/close returns null (no match). An empty ("") open and close returns an empty string.

 StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
 StringUtils.substringBetween(null, *, *)          = null
 StringUtils.substringBetween(*, null, *)          = null
 StringUtils.substringBetween(*, *, null)          = null
 StringUtils.substringBetween("", "", "")          = ""
 StringUtils.substringBetween("", "", "]")         = null
 StringUtils.substringBetween("", "[", "]")        = null
 StringUtils.substringBetween("yabcz", "", "")     = ""
 StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
 StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"
 

Parameters:

str - the String containing the substring, may be null

open - the String before the substring, may be null

close - the String after the substring, may be null

Returns:

the substring, null if no match

Since:

2.0