作业有问题吗?

public class Borrow {	
    public static void main(String[] args) throws CommandException, NoResultException {		
        Borrow borrow = new Borrow();		
        borrow.select();	
    }	
    public void select() throws CommandException, NoResultException {		
        String[] books = {"西游记", "红楼梦", "水浒传", "三国演义"};		
        Scanner input = new Scanner(System.in);		
        try {			
            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");			
            int ipt1 = input.nextInt();			
            if (ipt1 == 1) {				
                System.out.println("输入图书名称:");				
                String ipt2 = input.next();				
                String result = "";				
                for (String book : books) {					
                    if (ipt2.contentEquals(book)) {						
                        result = book;					
                    }				
                }				
                if (result != "") {					
                    System.out.println("book:" + result);				
                } else {					
                    throw new NoResultException("图书不存在!");				
                }			
            } else if (ipt1 == 2) {				
                System.out.println("输入图书序号:");				
                int ipt3 = input.nextInt();				
                if (ipt3 > books.length || ipt3 <= 0) {					
                    throw new NoResultException("图书不存在!");				
                } else if (ipt3 > 0 && ipt3 <= books.length) {					
                    System.out.println("book:" + books[ipt3 - 1]);				
                } else {					
                    throw new CommandException("命令输入错误!请根据提示输入数字命令!");				
                }			
            } else {				
                throw new CommandException("命令输入错误!请根据提示输入数字命令!");			
            }		
        } catch (CommandException e) {			
            System.out.println(e.getMessage());			
            select();		
        } catch (NoResultException e) {			
            System.out.println(e.getMessage());			
            select();		
        } catch (InputMismatchException e) {			
            System.out.println("命令输入错误!请根据提示输入数字命令!");			
            select();		
        }	
    }
}
public class CommandException extends Exception {	
    public CommandException() {	}	
    public CommandException(String e) {		
        super(e);	
    }
}
public class NoResultException extends Exception {	
    public NoResultException() { }	
    public NoResultException(String e) {		
        super(e);	
    }
}