上通大Refactoring Example:Pull Up Field SHANGHAI JIAO TONG UNIVERSITY public class User private String email; public class Player extends public class Player User private String email; //... //... 3 3 public class LeagueOwner public class LeagueOwner extends User private String eMail; //... //... 3 3 public class Advertiser public class Advertiser extends User private String //... email_address; 3 //... } Software EngineeringSoftware Engineering Refactoring Example: Pull Up Field public class Player { private String email; //... } public class LeagueOwner { private String eMail; //... } public class Advertiser { private String email_address; //... } public class User { private String email; } public class Player extends User { //... } public class LeagueOwner extends User { //... } public class Advertiser extends User { //... }