Java Bean Validation’s validateProperty() and validateValue() in Three Minutes

While it's not widely known, Java Bean Validation ships with the validateProperty() and validateValue() methods, which can be used for validating the individual fields of a constrained class as well as values even before assigning them.

I assume that you already have at least a basic background on how to use the standard for validating objects, but if you want to get a more intimate understanding on how this works, feel free to check my previous article, where I took an in-depth look at Bean Validation's core features.

Selective Validation of Field-Level Constraints

In a typical use case, a constrained domain class like the following will be validated in one single step with a Bean Validation implementation, like Hibernate Validator.

public class User {

    @NotEmpty(message = "Name may not be empty")
    @Size(min = 2, max = 32,
            message = "Name must be between 2 and 32 characters long")
    private String name;

    @NotEmpty(message = "Email may not be empty")
    @Email(message = "Email must be a well-formed email address")
    private String email;

    public User(){}

    public User(String name, String email) {
        this.name = name;
        this.email = email;
    }

    // setters and getters for name / email

}

But with validateProperty() and validateValue() the validation process can be performed more selectively.

The validateProperty() Method

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by Alejandro Gervasio via SitePoint