Builder模式构建器
当类中参数较多，且并非所有参数都必须设置时使用
优势：builder可以有多个可变参数；因为builder利用单独的方法来设置每个参数，你想要多少个可变参数，它们就可以有多少个
class Dog { private String name; private int age; private char sex; private Dog(Builder builder) { this.name = builder.name; this.age = builder.age; this.sex = builder.sex; } public static class Builder { private String name; private int age; private char sex; public Builder(String name) { this.name = name; } public Builder age(int age) { this.age = age; return this; } public Builder sex(char sex) { this.sex = sex; return this; } public Dog build() { return new Dog(this); } } @Override public String toString() { return "Dog [name=" + name + ", age=" + age + ", sex=" + sex + "]"; } } public class Demo { public static void main(String[] args) { Dog d = new Dog.Builder("姓名").age(10).sex('q').build(); //参数可以随意定义，顺序不限，个数不限 System.out.println(d); } }
