@Min, @Max for numeric constraints in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

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

The @Min annotation ensures that a numeric value is not less than a specified minimum value. It helps validate input data by enforcing a lower limit.

beginner

How does the @Max annotation work in Spring Boot validation?

The @Max annotation checks that a numeric value does not exceed a specified maximum value. It prevents values greater than the limit from being accepted.

intermediate

Can @Min and @Max be used together on the same field? What does that achieve?

Yes, using @Min and @Max together sets a range for valid numeric input. The value must be between the minimum and maximum limits inclusive.

beginner

What happens if a value violates the @Min or @Max constraint in Spring Boot?

If the value is outside the allowed range, Spring Boot validation fails and returns an error message. This helps prevent invalid data from being processed.

beginner

Show a simple example of using @Min and @Max on a field in a Spring Boot model class.

Example:
<pre>import javax.validation.constraints.Min;
import javax.validation.constraints.Max;

public class Product {
  @Min(1)
  @Max(100)
  private int quantity;

  // getters and setters
}</pre>
This means quantity must be between 1 and 100.

What does @Min(5) enforce on a numeric field?

A Value must be exactly 5

B Value must be at most 5

C Value must be at least 5

D Value must be between 0 and 5

@Min(5) means the value cannot be less than 5.

Which annotation ensures a number is not greater than a limit?

A @Max

B @Min

C @Size

D @NotNull

@Max sets the maximum allowed value.

If a field has @Min(1) and @Max(10), which value is invalid?

A 5

B 1

C 10

D 15

15 is greater than the max limit 10, so it is invalid.

What type of values can @Min and @Max be applied to?

A Numeric types like int, long, double

B Only Strings

C Boolean values

D Any object

@Min and @Max validate numeric values.

What happens if validation fails for @Min or @Max in Spring Boot?

A The application crashes

B An error message is returned

C The value is automatically corrected

D Nothing happens

Validation failure returns an error message to inform the user.

Explain how @Min and @Max annotations help in validating numeric input in Spring Boot.

Think about setting minimum and maximum allowed values.

Describe a real-life example where you would use @Min and @Max annotations in a Spring Boot application.

Consider a form input that must stay within a range.