我需要更简洁的代码

好的，以下是更简洁的代码实现：

import java.util.*;

public class NumberToEnglish {
    private static final String[] DIGITS = {"zero","one","two","three","four","five","six","seven","eight","nine"};
    private static final String[] TEENS = {"ten","eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen"};
    private static final String[] TENS = {"","","twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety"};

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入一个小于100的整数或英文单词：");
        String input = scanner.nextLine();
        if (isNumeric(input)) {
            int num = Integer.parseInt(input);
            if (num < 10) {
                System.out.println(DIGITS[num]);
            } else if (num < 20) {
                System.out.println(TEENS[num - 10]);
            } else {
                System.out.println(TENS[num / 10] + " " + DIGITS[num % 10]);
            }
        } else {
            String[] words = input.split(" ");
            if (words.length == 1) {
                System.out.println(getDigit(words[0]));
            } else if (words.length == 2) {
                System.out.println(getTens(words[0]) + " " + getDigit(words[1]));
            } else {
                System.out.println("输入不正确！");
            }
        }
    }

    private static boolean isNumeric(String str) {
        return str.matches("\\d+");
    }

    private static String getDigit(String word) {
        for (int i = 0; i < DIGITS.length; i++) {
            if (DIGITS[i].equals(word)) {
                return Integer.toString(i);
            }
        }
        return null;
    }

    private static String getTens(String word) {
        for (int i = 2; i < TENS.length; i++) {
            if (TENS[i].equals(word)) {
                return Integer.toString(i * 10);
            }
        }
        return null;
    }
}

在这个版本中，我将数字转换为英文的数组和常量放在了类的顶部，使代码更加简洁，同时使用了正则表达式判断输入是否为数字，简化了代码。此外，在 `getTens()` 方法中，我从数组的第2个元素开始循环，避免了在数组中添加空值的操作。