用java语言编写一个“模拟借书系统”

<pre name="code" class="java">import java.util.*;
public class book {

private static int x;
private static int num;
private static int num1;

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
bookname A1=new bookname();
booknum A2=new booknum();
Scanner s=new Scanner(System.in);
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{
x=s.nextInt();}
//throw new Exception("输入错误，请按提示输入数字命令！");
catch(Exception e){
System.out.println("输入错误，请按提示输入数字命令！");
book.main(null);}

if(x==1){ //按书名查找书籍
System.out.println("输入图书名称:");
String name=s.next();
A1.output(name);
//catch(Exception e){
//System.out.print("该图书不存在!");
//}

}

else if(x==2){//按序号查找书籍
System.out.println("输入图书序号(请输入数字命令:)");
num=s.nextInt();
A2.output1(num);
book.main(null);}

}
}

public class bookname extends book{
String[] str={"数学","语文","英语","物理","化学","生物"};
public static  boolean isHAVE(String[]str,String x){
for(int i=0;i<str.length;i++){
if(str[i].indexOf(x)!=-1){
return true;}
}
return false;

}

void output(String s){
if(isHAVE(str,s)){
System.out.println("book:"+s);
book.main(null);
}
else{
try{
throw new Exception("该图书不存在!");
}
catch(Exception e){
System.out.println(e.getMessage());
book.main(null);
}
//	System.out.println("该图书不存在");
//book.main(null);}
}
}
}

public class booknum extends bookname {
void output1(int x){
switch(x){
case 0:
System.out.println("book:"+(str[0]));
break;
case 1:
System.out.println("book:"+str[1]);
break;
case 2:
System.out.println("book:"+str[2]);
break;
case 3:
System.out.println("book:"+str[3]);
break;
case 4:
System.out.println("book:"+str[4]);
break;
case 5:
System.out.println("book:"+str[5]);
break;
default:
System.out.println("该图书不存在");}
}
}