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.

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; 

Answer 2

This is what I did.

Annotation

public @interface ValidateString {      String[] acceptedValues();      String message() default "{uk.dds.ideskos.validator.ValidateString.message}";      Class<?>[] groups() default { };      Class<? extends Payload>[] payload() default { };  } 

Validation Class

public class StringValidator implements ConstraintValidator<ValidateString, String>{      private List<String> valueList;      @Override     public void initialize(ValidateString constraintAnnotation) {         valueList = new ArrayList<String>();         for(String val : constraintAnnotation.acceptedValues()) {             valueList.add(val.toUpperCase());         }     }      @Override     public boolean isValid(String value, ConstraintValidatorContext context) {         return valueList.contains(value.toUpperCase());     }  } 

And i used it like

@ValidateString(acceptedValues={"Integer", "String"}, message="Invalid dataType") String dataType;  Long maxValue; Long minValue; 

Now I need to figure out how to implement conditional check ie. if String then maxValue and minValue should be null or Zero..

Any ideas?