package org.kuali.common.util.validate;
   
   import java.lang.reflect.Field;
   
   import org.apache.commons.lang3.StringUtils;
   import org.kuali.common.util.ReflectionUtils;
   
   import com.google.common.base.Optional;
   
  public class NoBlankStringsValidator extends AbstractFieldsValidator<NoBlankStrings, Object> {
  
  	@Override
  	protected Optional<String> validate(Field field, Object instance) {
  
  		// This field may not be a String
  		if (!ReflectionUtils.isString(field)) {
  			return Optional.absent();
  		}
  
  		// Extract the value of the field into an optional
  		Optional<?> fieldValue = ReflectionUtils.get(field, instance);
  
  		// We know the field contains a string at this point
  		String string = (String) fieldValue.orNull();
  
  		// Null is ok
  		if (string == null) {
  			return Optional.absent();
  		}
  
  		// Non-null value cannot be blank
  		if (StringUtils.isBlank(string)) {
  			return Validation.errorMessage(field, "blank strings not allowed");
  		} else {
  			return Optional.absent();
  		}
  	}
  
  }