@Email and @Pattern in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @Email annotation in Spring Boot?

The @Email annotation checks if a string is a valid email address format. It helps ensure users enter proper emails in forms.

beginner

How does the @Pattern annotation work in Spring Boot?

@Pattern validates a string against a regular expression (regex). It ensures the string matches a specific pattern you define.

beginner

Example usage of @Email annotation in a Spring Boot model?

You add @Email(message = "Invalid email") above a String field to check email format. Example:<br>@Email(message = "Invalid email")<br>private String userEmail;

intermediate

What happens if a string does not match the regex in @Pattern validation?

Spring Boot validation fails and returns an error message. You can customize the message with message = "Your message" in the annotation.

intermediate

Can @Email and @Pattern be used together on the same field?

Yes, you can combine them to enforce email format and additional pattern rules. Both validations run and must pass for the input to be valid.

What does the @Email annotation validate?

A If a number is positive

B If a string matches a regex pattern

C If a string is a valid email format

D If a field is not null

@Email checks if the string looks like a proper email address.

Which annotation uses a regular expression to validate a string?

A @Size

B @Email

C @NotNull

D @Pattern

@Pattern validates strings against regex patterns you provide.

How do you customize the error message shown when @Pattern validation fails?

A By overriding <code>toString()</code>

B Using <code>message</code> attribute in <code>@Pattern</code>

C Using <code>@ErrorMessage</code> annotation

D You cannot customize it

You add message = "Your message" inside @Pattern to customize errors.

Can @Email annotation alone guarantee the email domain is real?

A No, it only checks format

B Yes, it checks domain existence

C Yes, it sends a verification email

D No, it checks only length

@Email only checks if the email looks correct, not if the domain exists.

If you want to ensure a string contains only digits, which annotation is best?

A @Pattern(regexp = "\\d+")

B @Size(min=1)

C @NotNull

D @Email

@Pattern with regex \d+ ensures only digits are allowed.

Explain how you would use @Email and @Pattern annotations to validate a user input field in Spring Boot.

Think about combining format checks and pattern rules on the same field.

What are the limitations of @Email validation and how can @Pattern help overcome them?

Consider what @Email does not check and how regex can add control.