What is the difference between @NotEmpty, @NotBlank and @NotNull?

Question

Hibernate

I'm doing form validation in Spring using javax validation
But something didn't get the difference between annotations @NotNull, @NotBlankand @NotEmpty?
Oh, and even in the Oracle documentation I came across this code :

public class Name {
    @NotNull
    @Size(min=1, max=16)
    private String firstname;

    @NotNull 
    @Size(min=1, max=16)
    private String lastname;
    ...
}

and here I have a question, why use @NotNullif we have @Sizein which the minimum length is set ( min=1 ) ?

Answer 1

String name = null;
NotNull = false
NotEmpty = false
NotBlank = false

String nam = "";
NotNull = true
NotEmpty = false
NotBlank = false

String name = "  ";
NotNull = true
NotEmpty = true
NotBlank = false

String name = "zojian"
NotNull = true
NotEmpty = true
NotBlank = true