StringUtils tool class in Java performs analysis of judgment that String is empty

The criterion for determining whether a string is empty is str==null or str.length()==0

1. The following is an example of whether StringUtils is empty:

 StringUtils.isEmpty(null) = true StringUtils.isEmpty("") = true StringUtils.isEmpty(" ") = false //Note that the spaces are non-empty in StringUtils StringUtils.isEmpty(" ") = false StringUtils.isEmpty("bob") = false StringUtils.isEmpty("bob ") = false

2. public static boolean isNotEmpty(String str)

Determine whether a string is not empty, equal to !isEmpty(String str)

Here is an example:

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

3. public static boolean isBlank(String str)

Determine whether a string is empty or has a length of 0 or is composed of a whitespace character (whitespace)

Here is an example:

 StringUtils.isBlank(null) = true StringUtils.isBlank("") = true StringUtils.isBlank(" ") = true StringUtils.isBlank(" ") = true StringUtils.isBlank("/t /n /f /r") = true //For tabs, line breaks, page breaks and carriage return StringUtils.isBlank() //All are recognized as blanks StringUtils.isBlank("/b") = false //"/b" is the word boundary character StringUtils.isBlank("bob") = false StringUtils.isBlank("bob") = false StringUtils.isBlank("bob ") = false

4. public static boolean isNotBlank(String str)

Determine whether a string is not empty, its length is not 0, and it is not composed of whitespace, which is equal to !isBlank(String str)

Here is an example:

 StringUtils.isNotBlank(null) = false StringUtils.isNotBlank("") = false StringUtils.isNotBlank(" ") = false StringUtils.isNotBlank(" ") = false StringUtils.isNotBlank("/t /n /f /r") = false StringUtils.isNotBlank("/b") = true StringUtils.isNotBlank("bob") = true StringUtils.isNotBlank("bob") = true

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