java 构造函数处理缺少参数的情况

Question

我在这里有一个人详细信息的代码，并且无论给出多少可能的参数，都应该始终初始化该人，例如仅高度和年龄或薪水和年龄
我发现很难为每个参数组合声明一个构造函数，是否有比这更优化的解决方案？

class person {
    public static final int defalut_salary=1000;
    public static final int default_age=20;
    public static final double default_height=6;
    public static final String default_name="jack";

    protected int salary;
    protected int age;
    protected double height;
    protected String name;  

    person(){       
    }
}

Answer 1

我建议使用Builder模式:

public final class Person {
    private final int salary;
    private final int age;
    private final double height;
    private final String name;

    public Person(int salary, int age, double height, String name) {
        this.salary = salary;
        this.age = age;
        this.height = height;
        this.name = name;
    }

    // Getters or whatever you want

    public static class Builder {
        // Make each field default appropriately
        private int salary = 1000;
        private int age = 20;
        private double height = 6;
        private String name = "jack";

        public Builder setSalary(int salary) {
            this.salary = salary;
            return this;
        }

        // Ditto for other properties

        public Person build() {
            return new Person(salary, age, height, name);
        }
    }
}

用法:

Person person = new Person.Builder().setAge(25).setHeight(15).build();

您可以在 Person 构造函数中执行验证，如果您想要将任何字段设为必填，您可以在 Builder 中获取这些字段 构造函数。