Builder 建造者模

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Builder 建造者模式

本系列为 https://github.com/iluwatar/java-design-patterns 阅读笔记
之前读《java effective》时了解到Builder模式
至于为什么出现Builder模式参见 https://blog.csdn.net/lms1719/article/details/70741691
这个模式看似简单还是需要写一遍才行，
我敲了一遍中间出了很多错
Builder 声明public static class Builder

 public class Hero {

    private final String name;
    private final String gen;
    private final LocalDate birthday;

    public Hero(Builder builder) {//
        this.name = builder.name;
        this.gen = builder.gen;
        this.birthday = builder.birthday;
    }

    public static class Builder {
        private final String name;
        private String gen;
        private LocalDate birthday;

        public Builder(String name) {//必填参数
            this.name = name;
        }

        public Builder setGen(String gen){
            this.gen = gen;
            return this;//返回自身，链式创建
        }

        public Builder setBirthDay(LocalDate day){
            this.birthday = day;
            return this;
        }


        public Hero build(){//构造完成之后调用外部类构造函数
            return new Hero(this);
        }

    }

    public static void main(String[] args) {
        Hero build = new Builder("tom").setBirthDay(LocalDate.now()).build();
        System.out.println(build);
    }

}