Bean validation in the language, Study notes of Law

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Bean Validation

What is “Bean Validation”?

Validating input received from the user to maintain data integrity is an important part of application logic. Validation of data can take place at different layers in even the simplest of applications. The Java API for JavaBean Validation ("Bean Validation") provides a facility for validating objects, object members, methods, and constructors. In Java EE environments, Bean Validation integrates with Java EE containers and services to allow developers to easily define and enforce validation constraints. Bean Validation is available as part of the Java EE platform. Bean validation API packages available in Java EE API specification

1. javax.validation
2. javax.validation.bootstrap
3. javax.validation.constraints
4. javax.validation.constraintvalidation
5. javax.validation.executable
6. javax.validation.groups
7. javax.validation.metadata
8. javax.validation.spi
9. javax.validation.valueextraction Using Bean Validation constraints The Bean Validation model is supported by constraints in the form of annotations placed on a field, method, or class of a JavaBeans component, such as a managed bean. Two types of bean validation constraints
10. Built-in constraints Default implementation is available. All the built-in constrains are listed below (Available in javax.validation.constraints package) To use all of the below annotations you have to;
11. Download the bean validation jar file from Maven repository or Jakartha EE Speciication
12. Add the .jar file to the build path using;

BigDecimal area; @PositiveOrZero The value of the field or property must be a positive number or zero. @PositiveOrZero int totalGoals; @Size The size of the field or property is evaluated and must match the specified boundaries. If the field or property is a String , the size of the string is evaluated. If the field or property is a Collection , the size of the Collection is evaluated. If the field or property is a Map , the size of the Map is evaluated. If the field or property is an array, the size of the array is evaluated. Use one of the optional max or min elements to specify the boundaries. @Size(min=2, max=240) String briefMessage; Example:

Repeating annotations

In Bean Validation 2.0, you can specify the same constraint several times on a validation target using repeating annotation: Example: All in-built constraints from javax.validation.constraints package support repeatable annotations.

Validating empty and null strings

https://javaee.github.io/tutorial/bean-validation003.html Validating constructors and methods

2. User-defined / Custom constraints No built-in implementation is available. You have to define an implementation.