InterfacesSlide 2SyntaxCastingSlide 5Implementing Multiple InterfacesInterfacesInterfaces•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 – sortableSyntaxpublic interface interface_name {//method signaturepublic return_type name(params);}public class class_name implements interface_name {//method implementationpublic return_type name(params) {}}Castingpublic interface Animal {public void speak();}public class Bird implements Animal { public void speak() { System.out.println(“Squawk”);}public void fly() {...}} public class Cow implements Animal { public void speak() { System.out.println(“Moo”);}public void milk() {...}}CastingAnimal[] animals = new Animal[3];animals[0] = new Cow();animals[1] = new Bird(); animals[2] = new Cow();//milk all cowsfor(int i = 0; i < animals.length; i++) {if(animals[i] instanceof Cow) {Cow c = (Cow)animals[i];c.milk();}}Implementing Multiple Interfacespublic class class_name implements interface1, interface2, interface3 {//implementation of ALL methods from interfaces 1, 2, and 3}Example: interface Student with method listClassesinterface ComputerScientist with method writeProgramclass CSStudent implements Student and ComptuerScientistmust implement methods listClasses and
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