How to determine whether a string is empty in java

Java method to determine whether a string is empty:

First, distinguish between empty strings and null strings

1. The empty string "" is the length A string of 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(""));

2. Null string represents There is currently no object associated with this variable. How to check whether a string is null:

if (str == null);

3. To check whether 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 an error will occur when adjusting the length() method on a null value.

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

if (StringUtils.isNotBlank(str))

For more java knowledge, please pay attention to java basic tutorial.

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