public Book updatefield(int field, Book findbook) throws Exception {
		int inputcompleteup=0;
		Scanner scan = new Scanner(System.in);
		Book updatebook = findbook;
		switch (field) {
		case 1:
			do {
				System.out.print("Update title:");
				updatetitle = scan.nextLine();
				updatebook.settitle(updatetitle);
				inputcompleteup = 1;
			} while (inputcompleteup == 0);
			break;
		case 2:
			do {
				System.out.print("Update author:");
				updateauthor = scan.nextLine();
				updatebook.setauthor(updateauthor);
				inputcompleteup = 1;
			} while (inputcompleteup == 0);
			break;
		case 3:
			do {
				System.out.print("Update publish:");
				updatepublish = scan.nextLine();
				updatebook.setpublish(updatepublish);
				inputcompleteup = 1;
			} while (inputcompleteup == 0);
			break;
		case 4:
			do {
				System.out.print("Update ISBN:");
				updateISBN = scan.nextInt();
				if(1000>updateISBN || updateISBN>=10000){
					System.out.println("ISBN 4ڸ Էּ.(1000~9999)");
				}
				else{
					if (getequalISBN(updateISBN) == 1) {
						System.out.println("̹ ϵ ISBN̹Ƿ Ʈ  ϴ.");
					} else {
						updatebook.setISBN(updateISBN);
						inputcompleteup = 1;
					}
				}
			} while (inputcompleteup == 0);
			break;
		case 5:
			do {
				System.out.print("Update avail:");
				updateavail = scan.nextLine();
				findbook.setavail(updateavail);
				if (updateavail.equals("X"))
					updatebook.setborrower("");
				inputcompleteup = 1;
			} while (inputcompleteup == 0);
			break;
		case 6:
			do {
				System.out.print("Update borrower:");
				updateborrower = scan.nextLine();
				if (updateborrower.length() < 7) {
					System.out.println("borrower 7ڸ й Էּ.");
				} else {
					updatebook.setborrower(updateborrower);
					inputcompleteup = 1;
				}
			} while (inputcompleteup == 0);
			break;
		}
		return updatebook;
	}