What’s the difference between @NotBlank and @NotNull in Spring Boot?

@NotBlank checks strings for null, empty, or whitespace only. @NotNull just blocks nulls on any type—empties pass.

Should I use @Column(nullable = false) with @NotBlank?

Yes, always for strings. App validation + DB constraint = double-lock against bad data.

No—it's app validation only. Pair it with @Column(nullable = false) for schema enforcement.

Thought @NotBlank, @NotNull, and @Column(nullable=false) were interchangeable? They're not. Here's why mixing them up wrecks your backend.

Dev Digest Apr 11, 2026 4 min read

Layer @NotBlank/@NotNull (app validation) with @Column(nullable=false) (DB constraints) for full protection. 𝕏
@NotBlank is strings-only, rejects empties/whitespace; @NotNull is broader but laxer. 𝕏
In microservices, DB constraints prevent cross-service data poisoning. 𝕏

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#@NotBlank #@NotNull #JPA constraints #Spring Boot #Spring Boot validation #bean-validation #hibernate-validator #jpa-annotations

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