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up vote 2 down vote favorite

I am writing a URL validator. The code is as follows

public ValidationResult validate(final Object data, final Object root, final String path, final ValidationContext validationContext, final EvaluationContext evaluationContext) {

    ValidationResult validationResult = new ValidationResult();

    @SuppressWarnings("unchecked")
    List<URL> URLs = (List<URL>)data;

    UrlValidator urlValidator = new UrlValidator();
    boolean isValid = true;
    for (URL websiteURL : URLs) {

        if (urlValidator.isValid(websiteURL.getPath())) {
            isValid = true;
        } else {
            isValid = false;
            break;
        }
        System.out.println("websiteURL.getPath() " + websiteURL.getPath());         
    }
    System.out.println("websiteURL.getPath() " + isValid);  

    return validationResult;
}

While debugging i found that for (URL websiteURL : URLs) is giving java.lang.ClassCastException: java.net.URI cannot be cast to java.net.URL error. How can i make my logic work?

share|improve this question
up vote 1 down vote

The real problem is here:

@SuppressWarnings("unchecked")
List<URL> URLs = (List<URL>)data;

In fact, it would appear that you are calling this code with an object that is a list of URI objects rather than a list of URL objects. At any rate, the class cast is happening in a hidden cast that happens when the object returned by the Iterator.next() object is assigned to websiteURL.

It is not really clear what the correct solution to this is:

  • You could (possibly) change the code that calls this to pass it a list containing URL objects ... as expected by the validator.

  • You could change the validator to work on a list of URI objects ... starting with the declaration of the URLs variable. (YUCK! Didn't anyone explain Java identifier conventions to you??)

      @SuppressWarnings("unchecked")
  List<URI> uris = (List<URI>)data;

  • You could change the validator to work with URL and URI objects ... starting by changing the above declaration to:

      List<?> urls = (List) data;

    Then you need to use instanceof to discriminate between URI and URL objects before validating them.

For the record, the way to convert a URI to a URL is to call URI.toURL() on it.

share|improve this answer
    
why is it casting it to URI when i am giving URL in the list type ? How can i coerce it to be URL object. – CoderGuy Apr 7 '15 at 9:25
    
1) It is not being cast to URI. It is being cast to URL. And the cast is happening >>because<< you declared the list type as List<URL>. 2) See the last sentence of my Answer. However, you must get of the unchecked cast of the data to List<URL> because that is problematic. – Stephen C Apr 7 '15 at 10:35

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