i'm coding on a MongoDB java application.
I want to create a Collection of the objects (Type MongoDatabase) of every database from the mongoClient. Check
Next step: i want to extend the Type MongoDatabase to code some functions for my own. Folling error comes up: java.lang.ClassCastException: com.mongodb.MongoDatabaseImpl cannot be cast to model.ownMongoDatabase
I don't know why, but the old Java-driver has an DB-Class. Some changes are made to the Java-Driver (Version 3), and the function for the DB-Class are now marked as deprecated. Now you apperently have to use MongoDatabase. But MongoDatabase is an Interface, so no chance to extend it for my own Class?!
Code Snippet:
public class MongodbInstance extends com.mongodb.MongoClient {
private ArrayList<ownMongoDatabase > _mongodbDatabases = new ArrayList<ownMongoDatabase >();
private void buildMongodbDatabases(){
MongoCursor<String> iterator = this.listDatabaseNames().iterator(); // iterate through Databases
while(iterator.hasNext()){
this._mongodbDatabases.add((ownMongoDatabase) this.getDatabase(iterator.next())); // add Database-Object to Array
}
}
}
class ownMongoDatabase implements MongoDatabase {
}
Is there an tought mistake/coding failure? Thanks for your help.
this._mongodbDatabases.add((ownMongoDatabase) this.getDatabase(iterator.next()));
In this line you are trying to assign MongoDatabaseImpl to your ownMongoDatabase. This will for sure throw class cast exception.
Suppose you have class A which is parent class, Class B and Class C extends from Class A. You cannot assign class B to class C.
Try has-A relationship instead of is-A relationship.
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