Java 借书系统之异常练习

package Exception;
import java.util.*;
public class bookmanager {
    static Books[] book={new Books(1,"数据结构"),new Books(2,"论语")};//静态数组
    public static void main(String[] args) {
        bookmanager bkm = new bookmanager();
        bkm.mainsystem();//调用mainsystem
    }

    public void mainsystem(){
        try{
            book();
        }catch(BookException e){
            System.out.println(e.getMessage());
            mainsystem();//如果输入异常，在此调用mainsystem
        }
    }

    public void book() throws BookException{
        Scanner in = new Scanner(System.in);
        System.out.println("Input Command:1-Base oon name for book;2-Base on number for Book");
        try{    
            int num=in.nextInt();
            while(num>book.length || num<=0){//如果num大于数组长度或者小于等于0，重新输入
                System.out.println("Inexistence Value! Please Redo!");
                num=in.nextInt();
            }
            booktype(num);
        }catch(InputMismatchException e){
            throw new BookException("Command Error!");//异常捕获
        }
    }

    public void booktype(int num){
        Scanner in = new Scanner(System.in);//输入选项类型
        switch(num){
        case 1:
            System.out.println("The name of the book");
            String txt=in.next();
            bookselect(txt,0);
            break;
        case 2:
            System.out.println("The number of the book");
            num=in.nextInt();
            bookselect("",num);
            break;
        }
    }

    public void bookselect(String txt,int num){
            for(int i=0;i<=book.length;i++){
                if(txt.equals(book[i].getName()) || num==book[i].getNum()){
                    System.out.println("book:"+book[i].getName());//找到,输出名字
                    return;//找到,返回
                }
            }
            System.out.println("Inexistance Book!");
            mainsystem();//for循环之后没找到,调用mainsystem 回到开始

> 上面for循环是见解某位幕友的代码,在此感谢!

    }
}

package Exception;
//数组
public class Books {
    int num;
    String name;
    public Books(int num,String name){
        this.num=num;
        this.name=name;
    }
    public void setName(String name){
        this.name=name;
    }
    public String getName(){
        return name;
    }
    public void setNum(int num){
        this.num=num;
    }
    public int getNum(){
        return num;
    }
}

package Exception;
//自定义异常
@SuppressWarnings("serial")
public class BookException extends Exception{
    public BookException(String message){
        super(message);
    }
}