@Min, @Max for numeric constraints in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a minimum value constraint on the age field.

Spring Boot

@Min([1])
private int age;

Drag options to blanks, or click blank then click option'

A18

B0

C21

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using a negative number for minimum age.

Confusing @Min with @Max.

The @Min annotation sets the minimum allowed value for a numeric field. Here, 18 means age cannot be less than 18.

2fill in blank

medium

Complete the code to set a maximum value constraint on the score field.

Spring Boot

@Max([1])
private int score;

Drag options to blanks, or click blank then click option'

A10

B1000

C100

D50

Attempts:

3 left

💡 Hint

Common Mistakes

Setting maximum too low or too high.

Mixing up @Min and @Max annotations.

The @Max annotation sets the maximum allowed value. Here, 100 means the score cannot exceed 100.

3fill in blank

hard

Fix the error in the code by completing the annotation to restrict quantity between 1 and 10.

Spring Boot

@Min(1)
@Max([1])
private int quantity;

Drag options to blanks, or click blank then click option'

A5

B10

C15

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Setting max less than min causes validation errors.

Using zero or negative numbers for max.

The @Max annotation should be 10 to restrict quantity between 1 and 10 inclusive.

4fill in blank

hard

Fill both blanks to create a field 'rating' that must be between 1 and 5 inclusive.

Spring Boot

@Min([1])
@Max([2])
private int rating;

Drag options to blanks, or click blank then click option'

A1

B3

C5

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping min and max values.

Using values outside the 1-5 range.

The rating must be at least 1 and at most 5, so @Min(1) and @Max(5) are correct.

5fill in blank

hard

Fill all three blanks to define a field 'level' with minimum 0, maximum 10, and default value 5.

Spring Boot

@Min([1])
@Max([2])
private int level = [3];

Drag options to blanks, or click blank then click option'

A0

B10

C5

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Setting default value outside the min-max range.

Confusing min and max values.

The field 'level' must be between 0 and 10, so @Min(0) and @Max(10) are used. The default value is set to 5.

Practice

1.

What is the main purpose of using @Min and @Max annotations in Spring Boot?

easy

A. To define the length of a string

B. To enforce minimum and maximum numeric values on fields

C. To format dates in a specific pattern

D. To mark a method as a REST endpoint

Solution

1. Step 1: Identify purpose of @Min and @Max

   @Min and @Max set numeric limits on fields to ensure values stay within a range. Formatting dates, string length, and REST endpoints are unrelated.

2. Final Answer:

   To enforce minimum and maximum numeric values on fields -> Option B

3. Quick Check:

   @Min/@Max = numeric limits [OK]

Hint: Remember: @Min/@Max control numbers, not strings or dates [OK]

Common Mistakes:

• Confusing @Min/@Max with string length annotations
• Thinking they format dates
• Assuming they define REST endpoints

2.

Which of the following is the correct way to apply @Min and @Max annotations on an integer field age to restrict it between 18 and 65?

public class Person {
    // Which is correct?
    private int age;
}

easy

A. @Min(18) @Max(65) private int age;

B. @Min=18 @Max=65 private int age;

C. @Min{18} @Max{65} private int age;

D. @Min:18 @Max:65 private int age;

Solution

1. Step 1: Verify annotation syntax

   Annotations use parentheses with values, e.g., @Min(18), not =, {} or :. @Min(18) @Max(65) private int age; is correct; others invalid.

2. Final Answer:

   @Min(18) @Max(65) private int age; -> Option A

3. Quick Check:

   Annotations use (value) [OK]

Hint: Annotations always use parentheses for values [OK]

Common Mistakes:

• Using = or {} instead of () in annotations
• Forgetting to import javax.validation.constraints.*
• Placing annotations incorrectly outside the field

3.

Given the following Spring Boot entity snippet, what will happen if score is set to 105?

public class GameScore {
    @Min(0)
    @Max(100)
    private int score;

    // getters and setters
}

medium

A. Validation will fail because 105 is greater than the max 100

B. The value 105 will be accepted without error

C. Validation will fail because 105 is less than the min 0

D. The application will throw a NullPointerException

Solution

1. Step 1: Evaluate constraint for value 105

   @Min(0) requires >= 0; @Max(100) requires <= 100. 105 > 100 violates @Max, triggering validation failure.

2. Final Answer:

   Validation will fail because 105 is greater than the max 100 -> Option A

3. Quick Check:

   Value > @Max = error [OK]

Hint: Values outside @Min/@Max cause validation errors [OK]

Common Mistakes:

• Assuming values above max are accepted
• Confusing min and max roles
• Expecting runtime exceptions instead of validation errors

4.

Identify the error in this code snippet that uses @Min and @Max:

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

    // getters and setters
}

medium

A. No error, code is correct

B. The values 1 and 100 are invalid for @Min and @Max

C. Missing @NotNull annotation on quantity

D. Annotations @Min and @Max cannot be applied to String fields

Solution

1. Step 1: Check field type compatibility

   @Min/@Max apply only to numeric types (int, long, etc.), not String. quantity is String, causing validation error.

2. Final Answer:

   Annotations @Min and @Max cannot be applied to String fields -> Option D

3. Quick Check:

   @Min/@Max require numeric fields [OK]

Hint: Use @Min/@Max only on numbers, not strings [OK]

Common Mistakes:

• Applying @Min/@Max on non-numeric types
• Assuming @NotNull fixes type issues
• Ignoring type mismatch errors

5.

You want to create a Spring Boot model field rating that only accepts values from 1 to 5 inclusive. Which of the following code snippets correctly enforces this using @Min and @Max?

hard

A. public class Review {
@Min(0)
@Max(5)
private int rating;
}

B. public class Review {
@Min(1)
@Max(6)
private int rating;
}

C. public class Review {
@Min(1)
@Max(5)
private int rating;
}

D. public class Review {
@Min(1)
@Max(5)
private String rating;
}

Solution

1. Step 1: Select correct range and type

   1-5 inclusive requires @Min(1) @Max(5) on int. public class Review { @Min(1) @Max(5) private int rating; } matches; @Min(0) allows 0, @Max(6) allows 6, String invalid.

2. Final Answer:

   public class Review { @Min(1) @Max(5) private int rating; } -> Option C

3. Quick Check:

   @Min(1)/@Max(5) on int [OK]

Hint: Use int with @Min(1) and @Max(5) for rating 1-5 [OK]

Common Mistakes:

• Using wrong numeric ranges
• Applying annotations on String fields
• Setting min or max outside desired range