# 具体遇到的问题
请问老师,我这种写法更好还是把显示信息的函数写在类内好呢,

是否根据单一职责原则,这类业务函数不应写在类内?

Book.java

/**
 * 标题: 书
 *
 * @Author:
 * @Date: 2020/11/23 17:24
 */
public class Book {
private String bookname;
    private String writer;
    private String faxingshe;
    private double prize;

    public Book() {

    }
public Book(String bookname, String writer, String faxingshe, double prize) {
this.bookname = bookname;
        this.writer = writer;
        this.setFaxingshe(faxingshe);
        this.setPrize(prize);
    }

public String getBookname() {
return this.bookname;
    }

public String getWriter() {
return this.writer;
    }

public String getFaxingshe() {
return this.faxingshe;
    }

public void setFaxingshe(String faxingshe) {
this.faxingshe = faxingshe;
    }

public double getPrize() {
return this.prize;
    }

public void setPrize(double prize) {
if (prize<=10.0) {
            System.out.println("图书价格最低10元");
            this.prize = 10.0;
        }else {
this.prize = prize;
        }
    }

}

BookTest.java

/**
 * 标题: 测试类
 *
 * @Author:
 * @Date: 2020/11/23 17:24
 */
public class BookTest {
public static void introducebook(Book book) {
        System.out.println("书名:" + book.getBookname());
        System.out.println("作者:" + book.getWriter());
        System.out.println("出版社:" + book.getFaxingshe());
        System.out.println("价格:" + book.getPrize() + "元");
    }

public static void main(String[] args) {
        Book b1 = new Book("红楼梦","曹雪芹","人民文学出版社",10);
        Book b2 = new Book("小李飞刀","古龙","中国长安出版社",55.5);
        introducebook(b1);
        System.out.println("=========================================================");
        introducebook(b2);
    }
}