【每天学个新注解】Day 7 Lombok注解简解（六）—@With

@With

创建一个新的对象，该对象是当前对象的副本，但某些字段的值可以被更改。

1、如何使用

• @With 可以使用在类上，也可以使用在成员变量上。加在类上相当于给所有成员变量 @With
• 可以配合AccessLevel使用，创建出指定访问修饰符的with方法。

2、代码示例

例：

@AllArgsConstructor
@ToString
@With(AccessLevel.PRIVATE)
public class People {
    private String name;
    private int age;
    private String sex;

    public static void main(String[] args) {
        People p = new People("tom", 18, "男");
        People p1 = p.withAge(19).withSex("女");

        System.out.println(p.toString());
        System.out.println(p1.toString());
    }
}

编译后：创建出所有属性的with方法，并且访问修饰符为private，另外通过编译后的代码可以看出，with方法依赖有参构造方法，所以@With往往与@AllArgsConstructor共同使用。

public class People {
    private String name;
    private int age;
    private String sex;

    public static void main(String[] args) {
        People p = new People("tom", 18, "男");
        People p1 = p.withAge(19).withSex("女");
        System.out.println(p.toString());
        System.out.println(p1.toString());
    }

    @Generated
    public People(String name, int age, String sex) {
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

    @Generated
    public String toString() {
        return "People(name=" + this.name + ", age=" + this.age + ", sex=" + this.sex + ")";
    }

    @Generated
    private People withName(String name) {
        return this.name == name ? this : new People(name, this.age, this.sex);
    }

    @Generated
    private People withAge(int age) {
        return this.age == age ? this : new People(this.name, age, this.sex);
    }

    @Generated
    private People withSex(String sex) {
        return this.sex == sex ? this : new People(this.name, this.age, sex);
    }
}

代码输出结果：