This week's book giveaway is in the Agile and other Processes forum. We're giving away four copies of The Mikado Method and have Ola Ellnestam and Daniel Brolund on-line! See this thread for details.
Hi Friends Could u tell me as all the methods of the ResultSet interface is abstract but we use them like next() getString(String),getMetaData() etc. and they works HOW??? Where they are implemented ie which is the subclass of the ResultSet plus also for Statement,PreparedStatement and Connection interfaces ....
How do any calls to an interface work? At runtime the method is called on a class which implements the interface. And that class will be part of the driver supplied by the database vendor.
There is where the Database Drivers comes into place.
Now all database should support common operations of executing a query, trversion through the resultset, reading each column in a result, getting a connection,closing a connection ...etc.
So these standard operations are made as interface methods by Java.
Now the vendors who provide database drivers, implement this interface and hence they have to write their own implementation for each methods.
Say Oracle database driver will have its own logic/code of executing a query.
an SQL Server database driver will have its own logic/code for the same purpose. Since both implement the Statement interface, we the developers need not worry what method to call if its a oracle driver or sql server driver.
we just call the method in the interface, and based upon the driver that is loaded, those methods are called and executed.
In that way, Java allows any database vendor to write their drivers but all drivers will be in a standard way ,without confusing the developer.
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