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