This is probably a dumb question but I need to know. I have an interface as
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBAsync;
public interface AsyncClient extends AmazonDynamoDBAsync{
}
And I have a ClientCreator class which has the method
import com.company.clients.AsyncClient;
public class ClientCreator {
public static AsyncClient getAsyncClient() throws FileNotFoundException, IllegalArgumentException, IOException{
AmazonDynamoDBAsync client = new AmazonDynamoDBAsyncClient(getCredentials());
client.setRegion(getRegion());
return (AsyncClient)client;
}
.
.
.
Here AmazonDynamoDBAsyncClient implements AmazonDynamoDBAsync and AsyncClient extends AmazonDynamoDBAsync , but this code would not work and throws
com.amazonaws.services.dynamodbv2.AmazonDynamoDBAsyncClient cannot be cast to com.company.clients.AsyncClient
but why ?
Basically you've got the hierarchy like this:
AmazonDynamoDBAsync
^
|
-----------------------------
| |
AmazonDynamoDBAsyncClient AsyncClient
And you are trying to cast AmazonDynamoDBAsyncClient
instance to AsyncClient
, which isn't possible. Those are siblings. Take it like this: "Apple" and "Banana" are both "Fruit", but an "Apple" is not a "Banana".
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