@ NotEmpty, @ NotBlank, @ NotNull, @ notempty @ notblank

@ NotEmpty, @ NotBlank, @ NotNull, @ notempty @ notblank

@ NotEmpty used on the Collection class

@ NotBlank: Used on String

@ NotNull is used in basic types

 

 

Only simple results, but more specific content cannot be found, so I went to the source code and found the following annotations:

 

1. @ NotEmpty

/** 
* Asserts that the annotated string, collection, map or array is not {@code null} or empty. 
* 
* @author Emmanuel Bernard 
* @author Hardy Ferentschik 
*/

That is to say, the String class, Collection, Map, and array added with @ NotEmpty cannot be null or the length is 0 (the isEmpty () method of String, Collection, and Map ).

2. @ NotBlank

/** 
* Validate that the annotated string is not {@code null} or empty. 
* The difference to {@code NotEmpty} is that trailing whitespaces are getting ignored. 
* 
* @author Hardy Ferentschik 
*/

"The difference to {@ code NotEmpty} is that trailing whitespaces are getting ignored. "-> unlike {@ code NotEmpty}, trailing spaces are ignored. That is, strings with pure spaces do not comply with the rules. So it is said that @ NotBlank is used for String.

3. @ NotNull

/** 
* The annotated element must not be {@code null}. 
* Accepts any type. 
* 
* @author Emmanuel Bernard 
*/

This is easy to understand and cannot be null.