限制价格必须为10的问题？为什么价格为9时也是正常输出的？

public class Book {
   private String bookname;
   private String auther;
   private String press;

   public String getBookname() {
       return bookname;
   }

   public String getAuther() {
       return auther;
   }

   public String getPress() {
       return press;
   }

   public void setPress(String press) {
     this.press = press;
   }

   public double getPrice() {
       return price;
   }

   public void setPrice(double price) {
       if(price < 10){
           System.out.println("价格必须大于10");
           this.price = 10;
       }
       this.price = price;
   }

   private double price;

   public  Book(String bookname,String auther,String press,Double price){
       this.bookname = bookname;
       this.auther = auther;
       this.press = press;
       this.price = price;
   }
   public void info(){
       System.out.println("书名： "+bookname+'\n'+"作者： "+auther+'\n'+"出版社： "+press+'\n'+"价格： "+price);

   }

}

ublic class BookTest {
   public static void main(String[] args){
       Book bb = new Book("红楼梦","曹雪芹","人民文学出版社",9.00);
       bb.info();
       System.out.println("=====================");
       Book bb1 = new Book("小李飞刀","古龙","中国长安出版社",11.00);
       bb1.info();
   }
}

------------------------------------------------改过后的代码

public class Book {

    private String bookname;

    private String auther;

    private String press;

    private double price;

    public Book(String bookname,String auther,String press,double price){

    this.bookname = bookname;

    this.auther = auther;

    this.setPress(press);

    this.setPrice(price);

}

    //get和set方法

    public String getBookname() {

        return bookname;

    }

    public String getAuther() {

        return auther;

    }

    public String getPress() {

        return press;

    }

    public void setPress(String press) {

        this.press = press;

    }

    public double getPrice() {

        return price;

    }

    public void setPrice(double price) {

        if(price < 10){

            price=10.0;

        }

        this.price = price;  

    }

    public void info(){

        System.out.println("书名:"+bookname);

        System.out.println("作者:"+auther);

        System.out.println("出版社:"+press);

        System.out.println("价格:"+price+"元");

    }

}

public class BookTest {

    public static void main(String[] args){

        Book bb = new Book("红楼梦","曹雪芹","人名文学出版社",9.0);

        Book bb1= new Book("小李飞刀","古龙","中国长安出版社",55.5);

        bb.info();

        System.out.println("=======================");

        bb1.info();

    }

}