package api;

 // BEGIN: instanceof.class.InstanceProvider2

 import java.util.Arrays;

 import java.util.HashSet;

 import java.util.Set;

 import java.util.concurrent.Callable;

 public final class InstanceProvider {

     private final Callable<Object> instance;

     private final Set<String> types;

     public InstanceProvider(Callable<Object> instance) {

         this.instance = instance;

         this.types = null;

     }

     /** Specifies not only a factory for creating objects, but

      * also additional information about them.

      * @param instance the factory to create the object

      * @param type the class that the create object will be instance of

      * @since 2.0 

      */

     public InstanceProvider(Callable<Object> instance, String... types) {

         this.instance = instance;

         this.types = new HashSet<String>();

         this.types.addAll(Arrays.asList(types));

     }

     public Class<?> instanceClass() throws Exception {

         return instance.call().getClass();

     }

     public Object instanceCreate() throws Exception {

         return instance.call();

     }

     /** Allows to find out if the InstanceProvider creates object of given

      * type. This check can be done without loading the actual object or

      * its implementation class into memory.

      * 

      * @param c class to test 

      * @return if the instances produced by this provider is instance of c

      * @since 2.0 

      */

     public boolean isInstanceOf(Class<?> c) throws Exception {

         if (types != null) {

             return types.contains(c.getName());

         } else {

             // fallback

             return c.isAssignableFrom(instanceClass());

         }

     }

 }

 // END: instanceof.class.InstanceProvider2