遇到多个构造器参数时考虑用构建器_存在多个构造器-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_42218986/article/details/104534474

本文介绍了一个使用建造者模式创建营养成分事实类的具体实例。通过Builder模式，可以灵活地为NutritionFacts类设置参数，如份量大小、每份热量、脂肪、钠和碳水化合物含量等，而无需面对大量构造函数参数的问题。示例中，通过Builder模式构建了一杯可乐的营养成分信息。

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package com.sudy.alarm.test;

//Builder Pattern
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 {
        //required parameters
        private final int servingSize;
        private final int servings;
        //optional parameters
        private int calories = 0;
        private int fat = 0;
        private int carbohydrate = 0;
        private int sodium = 0;

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

        public Builder sodium(int val) {
            sodium = 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;
        sodium = builder.sodium;
        carbohydrate = builder.carbohydrate;
    }

    public static void main(String[] args) {
        NutritionFacts cocaCola = new Builder(240, 8).
                calories(100).sodium(35).carbohydrate(27).build();
    }
}