How to handle String input for for an Integer Field

 How to Make Integer field required and handle Strings?

Question:

I am getting the following error when i submit the form with an empty value for customer "freePasses". I am  using @NotNull on the field "freePasses". It is not throwing "is required" after validation after submit.
How to fix this? Please help.
Also, how do I handle validation if the user enters String input for the integer field?
-----
Answer:
Great question!
The root cause is the freePasses field is using a primitive type: int. In order to check for null we must use the appropriate wrapper class: Integer.
To resolve this, In Customer.java, replace "int" with "Integer"
@NotNull(message="is required")   
@Min(value=0, message="must be greater than or equal to zero")   
@Max(value=10, message="must be less than or equal to 10")   
private Integer freePasses;
Then update your getter/setter methods to use "Integer"
    public Integer getFreePasses() {
        return freePasses;
    }
    public void setFreePasses(Integer freePasses) {
        this.freePasses = freePasses;
    }
Save everything and retest.

=====
Here is the full source code.

package com.luv2code.springdemo.mvc;
import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;

public class Customer {

    private String firstName;
    
    @NotNull(message="is required")
    @Size(min=1, message="is required")
    private String lastName;

    @NotNull(message="is required")
    @Min(value=0, message="must be greater than or equal to zero")
    @Max(value=10, message="must be less than or equal to 10")
    private Integer freePasses;
    
    @Pattern(regexp="^[a-zA-Z0-9]{5}", message="only 5 chars/digits")
    private String postalCode;
        

    public String getPostalCode() {
        return postalCode;
    }

    public void setPostalCode(String postalCode) {
        this.postalCode = postalCode;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public Integer getFreePasses() {
        return freePasses;
    }

    public void setFreePasses(Integer freePasses) {
        this.freePasses = freePasses;
    }    
    
}

====
Handle String Input for Integer Fields
If the user enters String input such as "abcde" for the Free Passes integer field, we'd like to give a descriptive error message.

We basically need to override the default Spring MVC validation messages.
Follow these steps.
1. In your Eclipse project, expand the node: Java Resources
2. Right-click the src directory and create a new sub-directory: resources
3. Right-click the resources sub-directory and create a new file named: messages.properties
Your directory structure should look like this:

4. Add the following entry to the messages.properties file
typeMismatch.customer.freePasses=Invalid number
5. Save file
---
This file contains key/value pairs for the error message type
For a basic example:
  typeMismatch.customer.freePasses=Invalid number
The format of the error key is:   code + "." + object name + "." + field
To find out the given error code, in your Spring controller, you can log the details of the binding result
 System.out.println("Binding result: " + theBindingResult);  
For details, see the docs here
- http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/validation/DefaultMessageCodesResolver.html
---
6. Edit your config file: WEB-INF/spring-mvc-demo-servlet.xml
Add the following:

<bean id="messageSource" 
      class="org.springframework.context.support.ResourceBundleMessageSource">

    <property name="basenames" value="resources/messages" />

</bean>

7. Save the file. Restart the Tomcat server
8. Run your app and add bad data for the "Free Passes" field. You will see the error message from our properties file.