Kod źródłowy do wpisu o Java Bean Validation znajdującego się pod adresem: https://blog.mloza.pl/java-bean-validation-sprawdzanie-poprawnosci-przeslanych-danych/

Pet.java

public class Pet {
    @NotBlank
    private String name;

    public Pet(@NotBlank String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public Pet setName(String name) {
        this.name = name;
        return this;
    }
}

pom-simple.xml

    <dependencies>
        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>2.0.0.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate.validator</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>6.1.5.Final</version>
        </dependency>
      
        <dependency>
            <groupId>javax.el</groupId>
            <artifactId>javax.el-api</artifactId>
            <version>3.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.web</groupId>
            <artifactId>javax.el</artifactId>
            <version>2.2.6</version>
        </dependency>
    </dependencies>

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>bean-validation</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.3.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>2.0.0.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate.validator</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>6.1.5.Final</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <release>14</release>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

ProgrammaticValidation.java

public class ProgrammaticValidation {
    public static void main(String[] args) {
        ValidatorFactory factory = Validation.buildDefaultValidatorFactory(); // #1
        Validator validator = factory.getValidator();

        User user = new User(); // #2
        user.setName("");
        user.setAge(10);
        user.setAboutMe("short");
        user.setEmail("notAnEmail");
        user.setNotARobot(false);

        Set<ConstraintViolation<User>> violations = validator.validate(user); // #3
        System.out.println(violations);

        User validUser = new User();  // #4
        validUser.setName("Michal");
        validUser.setAge(30);
        validUser.setAboutMe("A little bit longer about me text. Text length should be in size constraints");
        validUser.setEmail("valid@email.com");
        validUser.setNotARobot(true);

        Set<ConstraintViolation<User>> noViolations = validator.validate(validUser);  // #5
        System.out.println(noViolations);
    }
}

User.java

public class User {

    @NotBlank
    private String name;

    @Min(value = 18, message = "You are to young to use our service")
    @Max(value = 150, message = "People are not live that long")
    private int age;

    @AssertTrue
    private boolean notARobot;

    @Email
    private String email;

    @Size(min = 50, max = 255, message = "Create a text that is between 50 and 255 charters long")
    private String aboutMe;
  
    // getters, setters...
}

UserPet.java

    @Valid
    @NotNull
    private Pet pet;

UserZip.java

private Optional<@Pattern(regexp = "\\d{2}-\\d{3}") String> zipCode;