package com.example.domain;public class Product {    private Long id;    private  String name;    public Product(Long id, String name) {        this.id = id;        this.name = name;    }    public Long getId() {        return id;    }    public void setId(Long id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "Product{" +                "id=" + id +                ", name='" + name + '\'' +                '}';    }    public static void main(String[] args){        Product product = new Product(1L,"demo");        System.out.println(product.toString());        change(product);        System.out.println(product.toString());    }    public static void change(Product product){        product.setName("demo_1");        product.setId(2L);        System.out.println(product.toString());        product = new Product(3L, "demo_2");        System.out.println(product.toString());    }}

　以上代码的输出结果：

Product{id=1, name='demo'}Product{id=2, name='demo_1'}Product{id=3, name='demo_2'}Product{id=2, name='demo_1'}