Wednesday, February 6, 2013

StringUtils.isEmtpty() vs StringUtils.isBlank()

Posted by Sharath Chandra

StringUtils.isEmpty() is used to find if the String is length 0 or null but StringUtils.isBlank() takes it a step forward. It not only checks if the String is length 0 or null, but also checks if it is only a whitespace string, i.e. "\s*".

1) 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
[Taken from Apache API reference ]

2) 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

isNotEmpty
public static boolean isNotEmpty(String str)
Checks if a String 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:
str - the String to check, may be null
Returns:
true if the String is not empty and not null

isNotBlank
public static boolean isNotBlank(String str)
Checks if a String is not empty (""), not null and not whitespace only.
 StringUtils.isNotBlank(null)      = false
 StringUtils.isNotBlank("")        = false
 StringUtils.isNotBlank(" ")       = false
 StringUtils.isNotBlank("bob")     = true
 StringUtils.isNotBlank("  bob  ") = true
 

Parameters:
str - the String to check, may be null
Returns:
true if the String is not empty and not null and not whitespace
Since:
2.0