ssd3,Exercise3

ssd3,Exercise3的习题，帮助大家学习Java。Prerequisites:Beforeyoubeginthisexercise,youneedmasteryofthefollowing:•ObjectOrientedProgrammingoKnowledgeofclassdesignClassattributesConstructorsAccessormethodsMutatormethodsoKnowledgeofinheritanceHowtoimplementaspecialization/generalizationrelation