Further Features of Interfaces
Interfaces are either public or have the default friendly access (public for the package and private elsewhere)
Methods in an interface are always abstract and have the same access as the interface. No other modifiers may be applied
Variables in an interface are public, static, and final. They must be initialized.
Interfaces can incorporate one or more other interfaces, using the extends keyword:
- public interface DoesItAll extends Storable, Paintable {
- public abstract void doesSomethingElse();
- }
A class can implement more than one interface:
- public class Picture implements Storable, Paintable {
- public void store(Stream s) {...}
- public void retrieve(Stream s) {...}
- public void refresh() {...}
- }