阶段练习--模拟借书系统
要求:
1.定义字符串数组保存图书信息;
2.提示用户输入,分别按"书名"和"图书序号"查找图书;
3.根据输入信息进行适当的异常处理
a.如果输入类型错误,抛出"错误命令异常",并提示重新输入;
b.如果书名不存在,抛出"图书不存在异常",并提示重新输入;
c.如果图书序号超过字符串数组范围,抛出"图书不存在异常",并提示重新输入;
博主把慕课上老师的代码和自己的做了下对比，有不同的意见欢迎大家拍砖:
慕课上老师的代码：
<span style="font-family:SimSun;font-size:18px;">package ExceptionTest;
import java.util.Scanner;
public class BookManagerEasy {
private static Scanner console = new Scanner(System.in);
public static void main(String[] args) {
//定义”图书“数组
String[] books = { "C语言", "数据结构", "汇编语言", "高数", "大学语文", "毛概" };
while (true) {
System.out.println("输入命令：1-按照名称查找图书；2-按照序号查找图书");
String book;
try {
//取得整型命令
int command = inputCommand();
//根据不同命令值，进行不同操作
switch (command) {
case 1://按照图书名称选择图书
book = getBookByName(books);
System.out.println("book:" + book);
break;
case 2://按照图书序号（数组下标）选择图书
book = getBookByNumber(books);
System.out.println("book:" + book);
break;
case -1://返回值为-1，说明输入有误
System.out.println("命令输入错误！请根据提示输入数字命令！");
continue;
default://其他值的命令均认为是错误命令
System.out.println("命令输入错误！");
continue;
}
break;//退出程序
} catch (Exception bne) {
//捕获”图书不存在异常“时，要求重新输入命令
System.out.println(bne.getMessage());
continue;
}
}
}
//按照图书名称查询图书
private static String getBookByName(String[] books)
throws Exception {
System.out.println("输入图书名称：");
//获取输入的图书名称
String name = console.next();
for (int i = 0; i < books.length; i++) {
if (name.equals(books[i]))
//输入的名称与某一图书名称匹配，返回该图书
return books[i];
}
//若无匹配，抛出”图书不存在异常“
throw new Exception("图书不存在！");
}
//根据图书序号（数组下标）查询图书
private static String getBookByNumber(String[] books)
throws Exception {
while (true) {
System.out.println("输入图书序号：");
try {
//获取输入的图书序号（数组下标）
int index = inputCommand();
//若返回值为-1
if(index == -1){
System.out.println("命令输入错误！请根据提示输入数字命令！");
continue;
}
//若不出现”数组下标越界异常“，则返回相应位置的图书
String book = books[index];
return book;
} catch (ArrayIndexOutOfBoundsException e) {
//输入的序号不存在（引发”数组下标越界异常“），则抛出”图书不存在异常“
Exception bookNotExists = new Exception("图书不存在！");
bookNotExists.initCause(e);
throw bookNotExists;
}
}
}
//从控制台输入命令，用于输入命令和输入图书序号
private static int inputCommand(){
int command;
try {
command = console.nextInt();
return command;
} catch (Exception e) {
//若输入字符型或者字符串，则抛出异常，捕获该异常，抛出”错误命令异常“
console = new Scanner(System.in);
//返回-1
return -1;
}
}
}</span><span style="font-family:KaiTi_GB2312;font-size:24px;">
</span>
博主的案例：
Book类:
package BookManger;
public class Book {
protected int bookId;
protected String bookName;
public Book(int bookId,String bookName){
this.bookId = bookId;
this.bookName = bookName;
}
public int getBookId() {
return bookId;
}
public void setBookId(int bookId) {
this.bookId = bookId;
}
public String getBookName() {
return bookName;
}
public void setBookName(String bookName) {
this.bookName = bookName;
}
@Override
public String toString() {
return "书号" + bookId + ", 书名: " + bookName;
}
}
CompturBook类:
package BookManger;
public class CompturBook extends Book{
public CompturBook(int bookId,String bookName){
super(bookId,bookName);
}
@Override
public String toString() {
return "书号" + bookId + ", 书名: " + bookName;
}
}
MathBook 类:
package BookManger;
public class MathBook extends Book{
public MathBook(int bookId,String bookName){
super(bookId,bookName);
}
public String toString() {
return "书号" + bookId + ", 书名: " + bookName;
}
}
BookMangerEasy类(主类):
package BookManger;
import java.util.*;
public class BookMangerEasy {
private static Scanner console = new Scanner(System.in);
public static void main(String[] args){
System.out.println("输入命令:1.按照书名查找图书;2.按照序号查找图书");
try{
sysInital();
}catch(RuntimeException e){
e.printStackTrace();
System.out.println("命令数字输入有误，请根据提示输入数字命令！");
main(null);
}
}
//系统初始化
public static void sysInital(){
Book[] book = {new CompturBook(1,"疯狂java"),new MathBook(2,"汤家凤高数")};
try{
int command = inputCommand();
//选择借书查询方式
//根据不同命令值，进行不同操作
switch (command) {
case 1://按照图书名称选择图书
getBookByName(book);
break;
case 2://按照图书序号（数组下标）选择图书
getBookByNumber(book);
break;
case -1: //返回值为-1，说明输入有误
System.out.println("命令输入错误！请根据提示输入数字命令！");
default://其他值的命令均认为是错误命令
System.out.println("命令输入错误！");
main(null);
}
}catch(Exception e){
RuntimeException newExc = new RuntimeException(e);
throw newExc;
}
}
//按照图书的序号去查询图书
public static void getBookByNumber(Book[] book) throws Exception {
System.out.print("输入图书序号：");
int id = inputCommand();
boolean mark = false;
try { for (Book book2 : book) {
if (book2.bookId == id) {
System.out.println("书名:" + book2.bookName);
mark = true;
}
}
if (!mark) System.out.println("图书不存在！");
main(null);
} catch (InputMismatchException e) {
throw new Exception("输入类型有误！");
}
}
//按照图书的名称去查询图书
public static void getBookByName(Book[] book) throws Exception{
System.out.println("输入图书名称:");
String name = sinputCommand();
boolean mark = false;
try{
for(Book book2:book){
if(book2.bookName.equals(name)){
System.out.println("book:"+book2.bookName);
mark = true;
}
}
if(!mark) System.out.println("图书不存在！");
main(null);
}catch(InputMismatchException e){
System.out.println(name);
}
}
//从控制台输入命令，用于输入命令和输入图书序号
private static int inputCommand(){
int command;
try{
command = console.nextInt();
return command;
}catch(Exception e){
//若输入字符型或者字符串,则抛出异常,捕获该异常,抛出"错误命令异常"
console = new Scanner(System.in);
//返回-1
return -1;
}
}
//用于图书的名称中的输入
private static String sinputCommand(){
String command;
try{
command = console.next();
return command;
}catch(Exception e){
console = new Scanner(System.in);
return "查询出现错误!";
}
}
}
在这里自己规避了while(true)..continue这种不爽的方法，用了main(null)这种循环方式，关于这个main(null)的解释见下一篇文章.
今天任务结束,至此异常类总结完毕,断言那篇转载的文章已经介绍的很详细辣,
总体来说，总结的还略粗糙，有错误的麻烦各位看官及时告知批评
