Discussion on: "Builder Pattern" generator for Java

Interesting tool. It's a pain to write these things by hand.

However, a note (or you may call it a feature request): with these templates, there is no check done by the builder that all or a mandatory subset of parameters have been given a value. You could use Optional<> to encode arguments that may not be necessary to construct the object; after all, one of the use cases of the Builder pattern is managing construction-time validation of the constructor arguments.

Another idea: there is at least another implementation style for the pattern; the one in which each step is encoded in a Class (or better, an Interface) so that the user must follow a precise call sequence in building the object. I.e:

class Point { 
  final int x, y; 
  private Point(int x, int y) {
    this.x = x; this.y = y;
  }

  static class PointY {
    final int x;
    PointY(int x) {
      this.x = x;
    }
    Point py(int y) {
      return new Point(x, y);
    }
  }

  static PointY px(int x) { 
    return new PointY(x); 
  } 
};

The Point class can only be instantiated in this way:

Point pt= Point.px(42).py(20);

This style may be useful when you want to thightly constrain how an object is created.