com.ctrip.framework.apollo.core.utils

Class StringUtils

java.lang.Object

com.ctrip.framework.apollo.core.utils.StringUtils

public class StringUtils
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	StringUtils.StringFormatter<T>

Field Summary

Fields

Modifier and Type	Field and Description
static String	EMPTY

Constructor Summary

Constructors

Constructor and Description
StringUtils()

Method Summary

Methods

Modifier and Type	Method and Description
static boolean	equals(String str1, String str2) Compares two Strings, returning true if they are equal.
static boolean	equalsIgnoreCase(String str1, String str2) Compares two Strings, returning true if they are equal ignoring the case.
static boolean	isBlank(String str) Checks if a String is whitespace, empty ("") or null.
static boolean	isContainEmpty(String... args)
static boolean	isEmpty(String str) Checks if a String is empty ("") or null.
static boolean	isNumeric(String str) Checks if the String contains only unicode digits.
static <T> String	join(Collection<T> collection, String separator)
static <T> String	join(Collection<T> collection, String separator, StringUtils.StringFormatter<T> formatter)
static boolean	startsWith(String str, String prefix) Check if a String starts with a specified prefix.
static boolean	startsWithIgnoreCase(String str, String prefix) Case insensitive check if a String starts with a specified prefix.
static String	trim(String str) Removes control characters (char <= 32) from both ends of this String, handling null by returning null.
static String	trimToEmpty(String str) Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.
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 is null.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final String EMPTY

See Also:

Constant Field Values

Constructor Detail

StringUtils

public StringUtils()

Method Detail

isEmpty

public static boolean isEmpty(String str)

Checks if a String 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 String. That functionality is available in isBlank().

Parameters:

str - the String to check, may be null

Returns:

true if the String is empty or null

isContainEmpty

public static boolean isContainEmpty(String... args)

isBlank

public static boolean isBlank(String str)

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

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

Parameters:

str - the String to check, may be null

Returns:

true if the String is null, empty or whitespace

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 is null.

The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use #stripToNull(String).

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

Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed String, null if only chars <= 32, empty or null String input

Since:

2.0

trimToEmpty

public static String trimToEmpty(String str)

Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.

The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use #stripToEmpty(String).

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

Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed String, or an empty String if null input

Since:

2.0

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. To strip whitespace use #strip(String).

To trim your choice of characters, use the #strip(String, String) methods.

 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(String str1,
             String str2)

Compares two Strings, returning true if they are equal.

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:

str1 - the first String, may be null

str2 - the second String, may be null

Returns:

true if the Strings are equal, case sensitive, or both null

See Also:

String.equals(Object)

equalsIgnoreCase

public static boolean equalsIgnoreCase(String str1,
                       String str2)

Compares two Strings, returning true if they are equal ignoring the case.

nulls are handled without exceptions. Two null references are considered equal. Comparison is case insensitive.

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

Parameters:

str1 - the first String, may be null

str2 - the second String, may be null

Returns:

true if the Strings are equal, case insensitive, or both null

See Also:

String.equalsIgnoreCase(String)

startsWith

public static boolean startsWith(String str,
                 String prefix)

Check if a String starts with a specified prefix.

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

 StringUtils.startsWith(null, null)      = true
 StringUtils.startsWith(null, "abc")     = false
 StringUtils.startsWith("abcdef", null)  = false
 StringUtils.startsWith("abcdef", "abc") = true
 StringUtils.startsWith("ABCDEF", "abc") = false
 

Parameters:

str - the String to check, may be null

prefix - the prefix to find, may be null

Returns:

true if the String starts with the prefix, case sensitive, or both null

Since:

2.4

See Also:

String.startsWith(String)

startsWithIgnoreCase

public static boolean startsWithIgnoreCase(String str,
                           String prefix)

Case insensitive check if a String starts with a specified prefix.

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

 StringUtils.startsWithIgnoreCase(null, null)      = true
 StringUtils.startsWithIgnoreCase(null, "abc")     = false
 StringUtils.startsWithIgnoreCase("abcdef", null)  = false
 StringUtils.startsWithIgnoreCase("abcdef", "abc") = true
 StringUtils.startsWithIgnoreCase("ABCDEF", "abc") = true
 

Parameters:

str - the String to check, may be null

prefix - the prefix to find, may be null

Returns:

true if the String starts with the prefix, case insensitive, or both null

Since:

2.4

See Also:

String.startsWith(String)

isNumeric

public static boolean isNumeric(String str)

Checks if the String contains only unicode digits. A decimal point is not a unicode digit and returns false.

null will return false. An empty String (length()=0) will return true.

 StringUtils.isNumeric(null)   = false
 StringUtils.isNumeric("")     = true
 StringUtils.isNumeric("  ")   = false
 StringUtils.isNumeric("123")  = true
 StringUtils.isNumeric("12 3") = false
 StringUtils.isNumeric("ab2c") = false
 StringUtils.isNumeric("12-3") = false
 StringUtils.isNumeric("12.3") = false
 

Parameters:

str - the String to check, may be null

Returns:

true if only contains digits, and is non-null

join

public static <T> String join(Collection<T> collection,
              String separator)

join

public static <T> String join(Collection<T> collection,
              String separator,
              StringUtils.StringFormatter<T> formatter)