防止用户在Java扫描仪中输入数字？

Question

I am having some trouble preventing the user from entering numbers with the scanner class. This is what I have:

package palindrome;

import java.util.Scanner;

public class Palindrome {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        String word;
        String inverse = "";

        System.out.println("Write a sentence or word: ");

        while (!input.hasNext("[A-Za-z]+")) {
        System.out.println("Not valid! Try again: ");
        input.nextLine();
    }
        word = input.nextLine();

        word = word.replaceAll("\\s+","");
        word = word.toLowerCase();

        int length = word.length();
        length = length - 1;

        for (int i = length; i >= 0; i--) {
            inverse = inverse + word.charAt(i);
        }

        if (word.equals(inverse)) {
            System.out.println("Is a palindrome.");
        } else {
            System.out.println("Is not a palindrome.");
        }

    }
}

Basically when I enter a word or sentence I want it to check if it has any numbers anywhere in the input, if it has then you need to enter another one until it doesn't. Here is an example of output:

• Write a sentence or word:

  --> 11

• Not valid! Try again:

  --> 1 test

• Not valid! Try again:

  --> test 1

• Is not a palindrome.

As you can see it works for most cases, but when I enter a word FIRST and then a space followed by a number it evaluates it without the number. I am assuming this is happening because in the while loop is checking for only input.hasNext but it should be input.hasNextLine I believe to check the entire string. However I cannot have any arguments if I do that. Help much appreciated!

Answer 1

将您的正则表达式从： [A-Za-z]+更改为^[A-Za-z]+$ ，以防止输入字符串中的任何数字