学习记录--遇到多个构造参数时考虑用构建器

public class NutritionFacts {

    private final int servingSize;

    private final int servings;

    private final int calories;

    private final int fat;

    private final int sodium;

    private final int carbohydrate;

    public static class Builder {

        private final int servingSize;

        private final int servings;

        private int calories = 0;

        private int fat = 0;

        private int sodium = 0;

        private int carbohydrate = 0;

        public Builder(int servingSize, int servings) {
            super();
            this.servingSize = servingSize;
            this.servings = servings;
        }

        public Builder calories(int val) {
            calories = val;
            return this;
        }

        public Builder fat(int val) {
            fat = val;
            return this;
        }

        public Builder sodium(int val) {
            sodium = val;
            return this;
        }

        public Builder carbohydrate(int val) {
            carbohydrate = val;
            return this;
        }

        public NutritionFacts build() {
            return new NutritionFacts(this);
        }
    }

    private NutritionFacts(Builder builder) {
        servingSize = builder.servingSize;
        servings = builder.servings;
        calories = builder.calories;
        fat = builder.fat;
        carbohydrate = builder.carbohydrate;
        sodium = builder.sodium;
    }

    public static void main(String[] args) {
        NutritionFacts cocaCola = new NutritionFacts.Builder(240, 8).calories(23).sodium(5).build();
    }
}