How to determine whether a string is empty or null in java?

#How does Java determine whether a string is empty or null?

First, distinguish between empty strings and null strings:

The empty string "" is a string of length 0, which has its own string length (0) and content (empty), the method to determine whether a string is empty:

 if (str.length() == 0)

or

if (str.equals(""))

null string means that there is currently no object associated with the variable, the method to check whether a string is null:

if (str == null)

Check that a string is neither a null string nor an empty string. Use the following method to determine:

if (str != null && str.length() != 0)

Note: You must first check that str is not null, otherwise in An error will occur if the length() method is increased by a null value.

Use the StringUtils tool class to determine whether it is neither null nor empty, as follows:

if (StringUtils.isNotBlank(str))

Recommended learning: Java video tutorial

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