package?com.imooc;
import?java.util.Scanner;

public?class?BorrowBook?{
	String[]?shu={"高數(shù)","大學(xué)英語","計算機(jī)"};
????Scanner?sc?=?new?Scanner(System.in);

public?void?test1(){
	System.out.println("輸入命令1或2：1代表按照書名查找圖書；2代表按照序號查找圖書");
}

public?void?test2()?throws?Exception{
	test1();
????int?a1=sc.nextInt();
????if?(a1!=1||a1!=2){?
	throw?new?Exception("命令輸入錯誤；請根據(jù)提示輸入數(shù)字命令！!");?
????}???
}
public?void?test3()?
{??try{??
	test2();
	}catch(Exception?e){
????test3();
}
if(a1==1){
	System.out.println("請輸入圖書名");
	String?a2=sc.next();
	for(int?i=0;i<3;i++){
		if(a2==shu[i])
			System.out.println("book:"+a2);
	}
}
	else?if(a1==2)
	{
		System.out.println("請輸入圖書序號");
		int?b2=?sc.nextInt();
		for(int?i=0;i<3;i++){
			if(b2==i)
				System.out.println("book:"+shu[i]);
	}
	System.out.println("圖書不存在");
}
}
}

請大神看一下（main方法放到別處了），錯誤是：a1 cannot be resolved to a variable。求解釋一下哈