java中的面向对象的练习

class Book{
    private String title;
    private int ;
    public Book(){
        //无参构造可以作为提示信息；例如：
        title = "未知";
        pageNum = "00";
    }    
    
    public Book(String s1, int s2){
        title = s1;
        pageNum = s2;//此处也可以进行页数判断。
    }
    public String getTitle(){
        return title;
    }
    public void setTitle(String t){
        title = t;
    }
    public int getPageNum(){
        return pageNum;
    }
    public void setPageNum(int n){
        if(n<200){
            System.out.println("页数不够200");
            pageNum = 200;
            return;
        }
        pageNum = n;
    }
    public void detail(){   //此处的方法不能用static 如果是则有 静态方法不能访问非静态变量的错误。
        //System.out.println(getTitle());
        System.out.println(this.title);
        //System.out.println(getPageNum());
        System.out.println(this.pageNum);
    }
}

public class Homework{
    public static void main(String[] args){
        Book one = new Book("fuck", 2510);
        one.detail();
        one.setTitle("fuck you");
        one.detail();
        one.setPageNum(150);
        one.detail();
    }
    
}