Java建立和銷毀對象的幾種方式__Java

建立對象的幾種方式 構造器 靜態Factory 方法 通過Builder
不直接產生想要的對象，而是讓用戶端利用所有必要的參數調用構造器，得到一個builder對象，然後用戶端在builder對象上調用類似於setter的方法，來設定每個選擇性參數，最後在用戶端調用無參的build()方法來產生對象。下面是一個簡單的樣本：

//builder patternpublic 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        private final int servingSize;        private final int servings;        //optional        private int calories =0;        private int fat =0;        private int sodium =0;        private int carbohydrate =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 sodium(int val){            sodium=val;            return this;        }        public Builder carbohydrate(int val){            carbohydrate=val;            return this;        }        //build 構造對象        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;    }}//用戶端調用NutritionFacts cocaCola = new NutritionFacts.Builder(20, 8).calories(100).sodium(35).carbohydrate(27).build()；