手记

Java入门自定义异常&模拟借书系统

要求:
提示用户输入 按照书名或者图书序号来查找信息;
如果用户输入信息有误就会抛出提示信息并且要求重新输入;

(1)定义图书查找异常类findexception,继承自Exception。

public class findexception extends Exception {

        public findexception(String message){

            super(message); 
        }
}

(2)编写一个查找图书系统类。

import java.util.*;

public class booktest {

    protected int id = 0;
    protected String name;
    static int i = 1;

    String[] books = new String[] { "论语", "高数", "英语" };

    public static Scanner sc = new Scanner(System.in);

    public booktest() {

    }

    public static void bookfind() throws findexception, InputMismatchException {

        System.out.println("输入命令:1-按照命令查找图书 2-按照序号查找图书");
        int com = sc.nextInt();

        if (com == 1) {

            i = 2;
            booktest bt = new booktest();
            bt.searchname();

        } else if (com == 2) {
            i = 2;
            booktest bt = new booktest();
            bt.searchtype();

        } else {
            throw new InputMismatchException("输入错误,请根据提示输入数字命令");

        }

    }

(3)测试类


Public class booktest{
    public static void main(String[] args) {
        booktest bt = new booktest();
        while (i == 1) {
            try {

                bookfind();

            } catch (findexception e) {

                System.out.println("图书不存在!");
                // System.out.println("输入命令:1-按照命令查找图书 2-按照序号查找图书");
                i = 1;
            } catch (ArrayIndexOutOfBoundsException e) {

                System.out.println("图书不存在!");
                i = 1;
            }

        }
    }

}
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