com.cronutils.utils

Class StringUtils

java.lang.Object

com.cronutils.utils.StringUtils

public class StringUtils
extends Object

Operations on String that are null safe.

• IsEmpty - checks if a String contains text
• IndexOfAny - index-of any of a set of Strings

The StringUtils class defines certain words related to String handling.

• null - null
• empty - a zero-length string ("")
• space - the space character (' ', char 32)
• whitespace - the characters defined by Character.isWhitespace(char)
• trim - the characters <= 32 as in String.trim()

StringUtils handles null input Strings quietly. That is to say that a null input will return null. Where a boolean or int is being returned details vary by method.

A side effect of the null handling is that a NullPointerException should be considered a bug in StringUtils.

Methods in this class give sample code to explain their operation. The symbol * is used to indicate any input including null.

#ThreadSafe#

Since:

1.0

Version:

$Id: StringUtils.java 1648067 2014-12-27 16:45:42Z britter $

See Also:

String

Field Summary

Fields

Modifier and Type	Field and Description
static String	EMPTY The empty String "".

Method Summary

Modifier and Type	Method and Description
static boolean	containsAny(CharSequence cs, char... searchChars) Checks if the CharSequence contains any character in the given.
static boolean	isEmpty(CharSequence cs) Checks if a CharSequence is empty ("") or null.
static boolean	isNumeric(CharSequence cs) Checks if the CharSequence contains only Unicode digits.
static String	join(Object[] parts, String separator) Joins the elements of the provided array into a single String containing the provided list of elements.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final String EMPTY

The empty String "".

Since:

2.0

See Also:

Constant Field Values

Method Detail

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)

containsAny

public static boolean containsAny(CharSequence cs,
                                  char... searchChars)

Checks if the CharSequence contains any character in the given. set of characters.

A null CharSequence will return false. A null or zero length search array will return false.

 StringUtils.containsAny(null, *)                = false
 StringUtils.containsAny("", *)                  = false
 StringUtils.containsAny(*, null)                = false
 StringUtils.containsAny(*, [])                  = false
 StringUtils.containsAny("zzabyycdxx",['z','a']) = true
 StringUtils.containsAny("zzabyycdxx",['b','y']) = true
 StringUtils.containsAny("aba", ['z'])           = false
 

Parameters:

cs - the CharSequence to check, may be null

searchChars - the chars to search for, may be null

Returns:

the true if any of the chars are found, false if no match or null input

Since:

2.4, 3.0 Changed signature from containsAny(String, char[]) to containsAny(CharSequence, char...)

isNumeric

public static boolean isNumeric(CharSequence cs)

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

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

Note that the method does not allow for a leading sign, either positive or negative. Also, if a String passes the numeric test, it may still generate a NumberFormatException when parsed by Integer.parseInt or Long.parseLong, e.g. if the value is outside the range for int or long respectively.

 StringUtils.isNumeric(null)   = false
 StringUtils.isNumeric("")     = false
 StringUtils.isNumeric("  ")   = false
 StringUtils.isNumeric("123")  = true
 StringUtils.isNumeric("१२३")  = true
 StringUtils.isNumeric("12 3") = false
 StringUtils.isNumeric("ab2c") = false
 StringUtils.isNumeric("12-3") = false
 StringUtils.isNumeric("12.3") = false
 StringUtils.isNumeric("-123") = false
 StringUtils.isNumeric("+123") = false
 

Parameters:

cs - the CharSequence to check, may be null

Returns:

true if only contains digits, and is non-null

Since:

3.0 Changed signature from isNumeric(String) to isNumeric(CharSequence), 3.0 Changed "" to return false and not true

join

public static String join(Object[] parts,
                          String separator)

Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

 StringUtils.join(null, *)                = null
 StringUtils.join([], *)                  = ""
 StringUtils.join([null], *)              = "null"
 StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
 StringUtils.join(["a", "b", "c"], null)  = "abc"
 StringUtils.join(["a", "b", "c"], "")    = "abc"
 StringUtils.join([null, "", "a"], ',')   = "null,,a"
 

Parameters:

parts - - the array of values to join together, may be null

separator - - the separator character to use, null treated as ""

Returns:

the joined String, null if null array input