为什么只能输入一个数字？

[recentlywe]

为什么只能输入一个数字，输入不了第二个数字？

public class Demo extends Exception {//自定义异常，必须继承Exception或其子类
	public Demo() {
		super();
	}
	public Demo(String code) {
		super(code);
	}
}

import java.util.Scanner;

public class Test {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("code:");
		Scanner input = new Scanner(System.in);
		
		try {
			int code = input.nextInt();
			show(code);
		} catch (Demo e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}catch(Exception e) {
			e.printStackTrace();
		}
		System.out.println("程序结束");
	}
	public static void show(int code) throws Demo{
		if(code<1||code>3) {
			throw new Demo("课程编码越界");//使用throws关键字声明异常对象
		}else if (code==1) {
			System.out.println("c++");
		}else if(code==2){
			System.out.println("java");
		}
		else {
			System.out.println("mysql");
		}
	}
}

[时间胶嚢]

加个循环就可以了 while(1){ try { int code = input.nextInt(); show(code); } catch (Demo e) { // TODO Auto-generated catch block e.printStackTrace(); }catch(Exception e) { e.printStackTrace(); } System.out.println("程序结束"); } }

[barton92]

稍微改了下，抛出异常就停止

public class Test { public static void main(String[] args) { // TODO Auto-generated method stub System.out.println("code:"); try { while(true) { show(); } } catch (Demo e) { // TODO Auto-generated catch block e.printStackTrace(); }catch(Exception e) { e.printStackTrace(); } System.out.println("程序结束"); } public static void show() throws Demo{ Scanner input = new Scanner(System.in); int code = input.nextInt(); if(code<1||code>3) { throw new Demo("课程编码越界");//使用throws关键字声明异常对象 }else if (code==1) { System.out.println("c++"); }else if(code==2){ System.out.println("java"); } else { System.out.println("mysql"); } } }