This interface defines a method that creates DatagramSocketImpl objects. You can register an instance of this factory interface with the static setDatagramSocketImplFactory( ) method of DatagramSocket. Application-level code never needs to use or implement this interface.

public interface DatagramSocketImplFactory {
// Public Instance Methods
     DatagramSocketImpl createDatagramSocketImpl( );  
}

Passed To

DatagramSocket.setDatagramSocketImplFactory( )