各位大神：交流下作業(yè)心得，煩請大家提提意見！

以下為源文件：
package?three1;

import?java.util.InputMismatchException;
import?java.util.Scanner;

import?com.sun.xml.internal.bind.v2.runtime.unmarshaller.XsiNilLoader.Array;

public?class?LibrarySystem?{

	//?圖書館現(xiàn)有書目
	private?String[]?books?=?{"高數(shù)","大物","英語"};
	
	//?按序號查找圖書
	public?void?findABook(?int?num?){
		try{
			System.out.println("book:"?+?books[num]);
		}catch?(InputMismatchException?e){
			System.out.println("命令輸入錯誤！請根據(jù)提示輸入數(shù)字命令！");
		}
		catch?(ArrayIndexOutOfBoundsException?e){
			System.out.println("圖書不存在！");
		}
	}
	
	//?按書名查找圖書
	public?boolean?findABook(?String?bookName?){
		for(?String?book:books){
			if(book.equalsIgnoreCase(bookName)){
				System.out.println("book:"?+?book);
				return?true;
			}
		}
		System.out.println("圖書不存在！");
		return?false;
	}
	
	public?static?void?main(String[]?args)?{
		//?TODO?Auto-generated?method?stub
		LibrarySystem?ls?=?new?LibrarySystem();
		
		Scanner?sc?=?new?Scanner(System.in);
		while(sc?!=?null){?
			System.out.println("輸入命令：1-按照名稱查找圖書；2-按照序號查找圖書。");
			
			try{
				int?commandNum?=?sc.nextInt();
				sc.nextLine();
				switch?(commandNum)?{
					case?1:
						System.out.println("輸入圖書名稱：");
						String?bookName?=?sc.nextLine();
						ls.findABook(bookName);
						break;
					case?2:
						System.out.println("輸入圖書序號：");
						int?bookNum?=?sc.nextInt();
						sc.nextLine();
						ls.findABook(bookNum);
						break;
					default:
						//輸入整數(shù)范圍有誤，拋出異常
						throw?new?Exception("0命令輸入錯誤！請根據(jù)提示輸入數(shù)字命令！");
				}
			}catch(InputMismatchException?e){
				System.out.println("命令輸入錯誤！請根據(jù)提示輸入數(shù)字命令！");
				sc.nextLine();
			}catch?(Exception?e){
				//e.printStackTrace();
				System.out.println("命令輸入錯誤！請根據(jù)提示輸入數(shù)字命令！");
			}
		}
	}
}