Interfaces Interfaces Generally interface describes public members of a class Java interface allows programmer to specify method signatures for reusability An interface cannot be instantiated A class that implements and interface must implement the methods defined in the interface Example sortable Syntax public interface interface name method signature public return type name params public class class name implements interface name method implementation public return type name params Casting public interface Animal public void speak public class Bird implements Animal public class Cow implements Animal public void speak public void speak System out println Moo System out println Squawk public void fly public void milk Casting Animal animals new Animal 3 animals 0 new Cow animals 1 new Bird animals 2 new Cow milk all cows for int i 0 i animals length i if animals i instanceof Cow Cow c Cow animals i c milk Implementing Multiple Interfaces public class class name implements interface1 interface2 interface3 implementation of ALL methods from interfaces 1 2 and 3 Example interface Student with method listClasses interface ComputerScientist with method writeProgram class CSStudent implements Student and ComptuerScientist must implement methods listClasses and writeProgram
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