- **总结：**  
  + 方法名尽量采用valueOf、of、getInstance、newInstance、getType、newType
  + 与构造器方式各有长处，灵活使用

#### 遇到多个构造器参数时要考虑构造器
静态工厂方法和构造器有一个共同的局限：他们不能很好的扩展到大量可选参数。一种思路是重叠构造器（telescoping constructor，多个构造器之前嵌套调用）可以解决，
但当参数过多时，客户端会很难编写。另一种思路是JavaBean模式，通过调用无参构造器来创建对象，然后使用`setter`方法设置属性值。

JavaBean模式存在致命的问题是：线程不安全，导致对象状态不一致
（类不能仅仅通过校验构造器参数的有效性来保证一致性，当多个线程共享一个对象时，简单的setter方法不能保证对象状态一致。）。   

第三种思路是Builder模式，既能保证想重叠构造器一样安全，又能实现JavaBean模式一样的可读性。
```java
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 - initialized to default values
        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();
    }
}