@NotBlank vs @Column(nullable = false) vs @NotNull — Which one should you use?

When I started working with Spring Boot, I thought all three did the same thing.

They don’t.

Understanding the difference between them helped me write cleaner and safer backend code.

1. @NotNull

• Prevents null
• Allow empty string "" and spaces " ".
• Provided by Hibernate Validator, used for application level validation.
• Works both for string and integer.

2. @NotBlank

• Prevents null, empty string "" and spaces " ".
• Provided by Bean Validation API(Hibernate Validator), used for application level validation.
• Works only for string.

3. @Column(nullable = false)

• This is not validation. It is database constraint.
• Prevents null
• Allow empty string "" and spaces " ".
• Provided by JPA, used for database level constraints.

Which is better?

Use both @NotBlank and @Column(nullable = false) for string to ensure data integrity at both levels. Use @NotNull if just presence of value is enough.

Comments

[buildbasekit]

@NotNull: “I just don’t want null, do whatever else you want 😌”

@notblank: “No empty drama either, bring real content 😤”

@column(nullable = false): “I don’t care what you validated… if it’s null, you’re not getting in 😎”

Spring Boot devs learning this the hard way at 2 AM 😅