Java String validation using enum values and annotation

Question

I want to validate a string against a set of values using annotations.

What I want is basically this:

@ValidateString(enumClass=com.co.enum)
String dataType;

int maxValue;
int minValue;
int precision;

or

@ValidateString(values={"String","Boolean", "Integer"})
String dataType;

int maxValue;
int minValue;
int precision;

I also want to do some validation on other variables depending upon the value set in dataType:

if (dataType = "String") {
    // maxValue, minValue, precision all should be null or zero
}

I can't think of a way to achieve this by custom annotations.
Somebody please help me.

question from:https://stackoverflow.com/questions/6294587/java-string-validation-using-enum-values-and-annotation

Answer 1

So here is the code being using Spring validation and works great for me. Full code is given below.

---

@EnumValidator annotation definition:

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import javax.validation.Constraint;
import javax.validation.Payload;
import javax.validation.ReportAsSingleViolation;
import javax.validation.constraints.NotNull;

@Documented
@Constraint(validatedBy = EnumValidatorImpl.class)
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
@NotNull(message = "Value cannot be null")
@ReportAsSingleViolation
public @interface EnumValidator {

  Class<? extends Enum<?>> enumClazz();

  String message() default "Value is not valid";

  Class<?>[] groups() default {};

  Class<? extends Payload>[] payload() default {};

}

Implementation of the above class:

import java.util.ArrayList;
import java.util.List;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

public class EnumValidatorImpl implements ConstraintValidator<EnumValidator, String> {

    List<String> valueList = null;

    @Override
    public boolean isValid(String value, ConstraintValidatorContext context) {
        return valueList.contains(value.toUpperCase());
    }

    @Override
    public void initialize(EnumValidator constraintAnnotation) {
        valueList = new ArrayList<String>();
        Class<? extends Enum<?>> enumClass = constraintAnnotation.enumClazz();

        @SuppressWarnings("rawtypes")
        Enum[] enumValArr = enumClass.getEnumConstants();

        for (@SuppressWarnings("rawtypes") Enum enumVal : enumValArr) {
            valueList.add(enumVal.toString().toUpperCase());
        }
    }

}

Usage of the above annotation is very simple

 @JsonProperty("lead_id")
 @EnumValidator(
     enumClazz = DefaultEnum.class,
     message = "This error is coming from the enum class",
     groups = {Group1.class}
 )
 private String leadId;