Spring-boot读书笔记一@builder

the complete details of what Lombok's @Builder annotation generates for the CourseNameRating class:

Generated Builder Class (by Lombok):

// This entire class is generated by Lombok at compile time
public static class CourseNameRatingBuilder {// Private fields to store values during buildingprivate String name;private int rating;// Default constructorCourseNameRatingBuilder() {}// Setter method for name (returns builder for chaining)public CourseNameRatingBuilder name(String name) {this.name = name;return this;  // Returns 'this' for method chaining}// Setter method for rating (returns builder for chaining)  public CourseNameRatingBuilder rating(int rating) {this.rating = rating;return this;  // Returns 'this' for method chaining}// Build method - creates the final objectpublic CourseNameRating build() {return new CourseNameRating(this.name, this.rating);}// toString method for debuggingpublic String toString() {return "CourseNameRating.CourseNameRatingBuilder(name=" + this.name + ", rating=" + this.rating + ")";}
}// Static factory method (also generated by Lombok)
public static CourseNameRatingBuilder builder() {return new CourseNameRatingBuilder();
}

How it works step by step:
1. CourseNameRating.builder()

• Calls the static factory method
• Creates and returns a new CourseNameRatingBuilder instance
  2. .name(course.getName())
• Calls CourseNameRatingBuilder.name(String name)
• Sets this.name = "Spring Boot" (example)
• Returns the same builder instance
  3. .rating(course.getRating())
• Calls CourseNameRatingBuilder.rating(int rating)
• Sets this.rating = 4 (example)
• Returns the same builder instance
  4. .build()
• Calls CourseNameRatingBuilder.build()
• Creates new CourseNameRating("Spring Boot", 4)
• Returns the completed CourseNameRating object

Key Features:

• Method chaining: Each setter returns this
• Immutable result: Final object can't be changed after creation
• Type safety: Compile-time checking of required fields
• Clean API: Fluent, readable object construction