Why can't my compiler convert this?
Error:
Type mismatch: cannot convert from Set<ConstraintViolation<capture#1-of ?>> to Set<ConstraintViolation<Class<?>>>
My code:
public class validateValue(Class<?> beanType, String propertyName, Object v开发者_运维技巧alue, Class<?>... groups){
TraversableResolver tr = new MyTraversableResolver();
Validator validator = Validation.buildDefaultValidatorFactory().usingContext().traversableResolver(tr).getValidator();
final Set<ConstraintViolation<Class<?>>> constraintViolations = validator.validateValue(beanType, propertyName, value, groups);
}
private class MyTraversableResolver implements TraversableResolver {
public boolean isReachable(Object traversableObject, Path.Node traversableProperty, Class<?> rootBeanType, Path pathToTraversableObject, ElementType elementType) {
return traversableObject == null || Hibernate.isInitialized(traversableObject);
}
public boolean isCascadable(Object traversableObject, Path.Node traversableProperty, Class<?> rootBeanType, Path pathToTraversableObject, ElementType elementType) {
return true;
}
}
I think the problem is your compiler doesn't know that the type of your beanType variable matches the set. Try something like this (code may need to be tweaked a bit)
public <T> class validateValue(Class<T> beanType, String propertyName, Object value, Class<?>... groups)
Then changing:
final Set<ConstraintViolation<Class<?>>>
to
final Set<ConstraintViolation<Class<T>>>
@JustinKSU is correct about changing the wildcard (?) to a type arg (T). The other issue is that validator.validateValue(Class<T> beanType, String propertyName, Object value, Class<?>... groups)
doesn't return a set of constraint violations on the type's class, which would be:
Set<ConstraintViolation<Class<T>>>
...but rather it returns a set of constraint violations on the type:
Set<ConstraintViolation<T>>
It's a subtle difference to see, but it's noticeable if you check the error message closely and count the angle brackets.
So, your code should be as below. I simplified the validator creation for purposes of the example. I also added a return value since I assume you want to do something with the results.
public <T> Set<ConstraintViolation<T>> validateValue(Class<T> beanType, String propertyName, Object value, Class<?>... groups) {
Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
final Set<ConstraintViolation<T>> constraintViolations = validator.validateValue(beanType, propertyName, value, groups);
return constraintViolations;
}
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