public class Test { public static boolean a; public void ex() throws MyException{ if (a == false){ throw new MyException("輸入有誤，請重新輸入"); } } public static void main(String[] args) { // TODO Auto-generated method stub System.out.println("輸入1表示按照書名查找書籍，輸入2表示按照書的序號查找書籍"); Scanner input = new Scanner(System.in); int a = input.nextInt(); if (a == 1){ System.out.println("請輸入書籍名稱"); Scanner input1 = new Scanner(System.in); String b = input1.toString(); switch (b) { case "高數": System.out.println(new Book().getBook1()); break; case "數據結構": System.out.println(new Book().getBood2()); break; default: Test.a = false; break; } } }}