如何限制为只读属性？如果限制成只读属性，岂不是不能set了？

而且构造函数初始化的时候一定会要set呀

相关代码：

​public class Book {
	private String bookname;
	private String writer;
	private String publish;
	double price;

	public void setBookname(String bookname) {
		this.bookname = bookname;
	}

	public void setWriter(String writer) {
		this.writer = writer;
	}

	public String getBookname() {
		return bookname;
	}

	public String getWriter() {
		return writer;
	}

	public String getPublish() {
		return publish;
	}

	public void setPublish(String publish) {
		this.publish = publish;
	}

	public double getPrice() {
		return price;
	}

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

	}

	public Book(String bookname,String writer,String publish,double price) {
		this.setBookname(bookname);
		this.setWriter(writer);
		this.setPublish(publish);
		this.setPrice(price);
	}

	public void BookDisplay() {
		System.out.println("书名："+this.bookname);
		System.out.println("作者："+this.writer);
		System.out.println("出版社："+this.publish);
		System.out.println("价格："+this.price+"元");
	}

}