@Min, @Max for numeric constraints in Spring Boot - Mini Project: Build & Apply

Using @Min and @Max for Numeric Validation in Spring Boot

📖 Scenario: You are building a simple Spring Boot application that accepts user input for product quantities. You want to make sure the quantity is never less than 1 and never more than 100.

🎯 Goal: Create a Spring Boot model class with a numeric field quantity that uses @Min and @Max annotations to enforce these limits.

📋 What You'll Learn

Create a model class named OrderItem

Add an integer field named quantity

Use @Min(1) annotation on quantity

Use @Max(100) annotation on quantity

Include getter and setter for quantity

💡 Why This Matters

🌍 Real World

Numeric constraints like @Min and @Max help ensure data integrity in applications, such as limiting order quantities or age inputs.

💼 Career

Understanding validation annotations is essential for backend developers working with Spring Boot to build robust and user-friendly APIs.

1

Create the OrderItem class with quantity field

Create a public class named OrderItem and add a private integer field called quantity.

Spring Boot

public class OrderItem {
    // Your code here
}

Need a hint?

Define the class and then declare the quantity field as an integer.

2

Add @Min annotation to quantity

Add the @Min(1) annotation above the quantity field to ensure the minimum value is 1. Import javax.validation.constraints.Min.

Spring Boot

import javax.validation.constraints.Min;

public class OrderItem {
    // Add @Min(1) annotation here
    private int quantity;
}

Need a hint?

Place @Min(1) directly above the quantity field.

3

Add @Max annotation to quantity

Add the @Max(100) annotation above the quantity field to ensure the maximum value is 100. Import javax.validation.constraints.Max.

Spring Boot

import javax.validation.constraints.Max;

public class OrderItem {
    @Min(1)
    // Add @Max(100) annotation here
    private int quantity;
}

Need a hint?

Place @Max(100) directly above the quantity field, below @Min(1).

4

Add getter and setter for quantity

Add a public getter method named getQuantity() and a public setter method named setQuantity(int quantity) for the quantity field.

Spring Boot

import javax.validation.constraints.Min;
import javax.validation.constraints.Max;

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

    // Add getter and setter methods here
}

Need a hint?

Write standard getter and setter methods for the quantity field.