遇到多个构造器参数时要考虑用构建器

1.当一个类有很多参数,其中一些是必须的,一些是可选的时候,使用构建器清晰明了:
下面的类可以修改为构造器

/** * Created by kaizige on 2017/7/3. */public class Person {    private  int age;//必须    private String name;//必须    private String sex;//必须    private String father;    private String mother;    public Person(int age, String name, String sex, String father, String mother) {        this.age = age;        this.name = name;        this.sex = sex;        this.father = father;        this.mother = mother;    }    public Person(int age, String name, String sex,String father){        this(age,name,sex,father,null);    }    public Person(int age, String name, String sex){        this(age,name,sex,null,null);    }}/** * Created by kaizige on 2017/7/3. */public class Person2 {    private  int age;//必须    private String name;//必须    private String sex;//必须    private String father;    private String mother;    @Override    public String toString() {        return "Person2{" +                "age=" + age +                ", name='" + name + '\'' +                ", sex='" + sex + '\'' +                ", father='" + father + '\'' +                ", mother='" + mother + '\'' +                '}';    }    public Person2(Builder builder){        this.age=builder.age;        this.name=builder.name;        this.father=builder.father;        this.mother=builder.mother;        this.sex=builder.sex;    }    public  static class Builder{        private  int age;//必须        private String name;//必须        private String sex;//必须        private String father=null;        private String mother=null;        public Builder(int age, String name, String sex){            this.age = age;            this.name = name;            this.sex = sex;        }        public Builder withFather(String father){            this.father=father;            return this;        }        public Builder withMother(String mother){            this.mother=mother;            return this;        }        public Person2 build(){            return new Person2(this);        }    }    public static void main(String[] args) {        System.out.println(new Builder(22,"杨凯","男").withFather("杨").withMother("王").build());    }}