@NotNull,@NotEmpty,@NotBlank cognitive verification
in conclusion:
@NotNull, which means that the object is not null,
@NotEmpty. indicates that the object is not null and the data of the elements in the object cannot be 0,
@NotBlank, which means that the object cannot be null and the number of elements in the object (after using the trim() method) is not 0.
user target audience ,
@NotNull can be applied to different objects, such as Integer, String, and collections. It is generally used in Integer basic data type packaging classes.
@NotEmpty can be used for String, but not for Integer objects, generally used on collection properties
@NotBlank, can only be applied to String objects, generally the same as @NotBlank
For @ ApiModelProperty in allowEmptyValue , it is not for @NotEmpty, and @NotBlank influential.
The page on the swagger corresponding to @ApiModelProperty is displayed, and @NotNull, @NotEmpty, and @NotBlank are validator annotations.
The null in the database is the same as this.
The @DecimalMin annotation does not judge the null value, so it has no effect on @NotNull, @NotEmpty, and @NotBlank.
Another point to say is that when using reference variables, you must verify that they are non-null.