无限循环输入

1.推荐 呕心沥血,自己写的!

public class Hello {
	public static void main(String[] args)  {
		inputScore();
	}
	
	public static void inputScore(){

		while(true){
			try {
				System.out.println("请输入您的分数:");
				BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
				String score = bf.readLine();
				String regex = "^[0-9]\d*$";
				if(score.equalsIgnoreCase("quit")){
					System.out.println("谢谢你的使用,欢迎下次光临.");
					System.exit(0);
				}
				if(score.matches(regex)){
					getGrade(Integer.parseInt(score));
				}
				System.out.println("如果想退出输入,请输入quit");
			} catch (Exception e) {
				System.out.println("2222");
				throw new RuntimeException("您的输入有误...");
			}
		}
	}
	
	public static void getGrade(int score){
		if(score >= 90){
			System.out.println("优秀");
		}else if(score >= 80){
			System.out.println("良好");
		}else if(score >= 70){
			System.out.println("一般");
		}else if(score >= 60){
			System.out.println("差强人意");
		}else if( score >= 0){
			System.out.println("补考");
		}else{
			System.out.println("您的输入有误,请重新输入:");
		}
	}

}

　　2. 普通的单次输入

public class Hello {
	public static void main(String[] args)  {
		Scanner scanner = new Scanner(System.in);
		boolean flag = true;
		while(flag){
			try {
				System.out.println("请输入您的分数:");
				int score = scanner.nextInt();
				getGrade(score);
			
			} catch (Exception e) {
				System.out.println("分数必须是数字! 请重新输入:");
				flag = false;
			}
		}
	}

    public static void getGrade(int score){
		if(score >= 90){
			System.out.println("优秀");
		}else if(score >= 80){
			System.out.println("良好");
		}else if(score >= 70){
			System.out.println("一般");
		}else if(score >= 60){
			System.out.println("差强人意");
		}else if( score >= 0){
			System.out.println("补考");
		}else{
			System.out.println("您的输入有误,请重新输入:");
		}
	}

}