避免写出难以理解的大类

避免写出难以理解的大类

• 原因：一个人理解的东西是有限的，没人能面对所有的细节
• 大类的产生：
  • 职责不单一
  • 字段未分组
• 操作要点：把类写小，越小越好

案例1:

public class User {
  private long userId;
  private String name;
  private String nickname;
  private String email;
  private String phoneNumber;
  private AuthorType authorType;
  private ReviewStatus authorReviewStatus;
  private EditorType editorType;
  ...
}

问题：userId,name这些是和用户关联的，后面的AuthorType，ReviewStatus，EditorType和用户信息无关

修正：AuthorType，ReviewStatus，EditorType和用户信息无关 拆成单独的类，通过userId去关联

public class Author {
  private long userId;
  private AuthorType authorType;
  private ReviewStatus authorReviewStatus;
  ...
}

public class Editor {
  private long userId;
  private EditorType editorType;
  ...
}

案例2

public class User {
  private long userId;
  private String name;
  private String nickname;
  private String email;
  private String phoneNumber;
  ...
}

问题：这个类中userId，name，nickname是属于用户的基本信息，而email，phoneNumber其实是属于用户的联系方式

修正：对字段进行分组，把email，phoneNumber放在单独的contact类

public class User {
  private long userId;
  private String name;
  private String nickname;
  private Contact contact;
  ...
}

public class Contact {
  private String email;
  private String phoneNumber;
  ...
}