Poechant 练习 Java API - Y/N 输入验证

循环输入，直到控制台输入的内容为Y/y或N/n才结束，输入其他内容则提示错误。

import java.util.Scanner;

public class test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		boolean isValid = false;
		while (!isValid) {
			String str = sc.next(); 
			if (str.equalsIgnoreCase("y")) {
				System.out.println("YES");
				isValid = true;
			} else if (str.equalsIgnoreCase("n")) {
				System.out.println("NO");
				isValid = true;
			} else {
				System.out.println("Please input \"y\" or \"n\"");
			}
		}
	}
}