计算一个句子中元音和辅音的数量的 Java 程序

public class Main {

  public static void main(String[] args) {
    String line = "This website is aw3som3.";
    int vowels = 0, consonants = 0, digits = 0, spaces = 0;

    line = line.toLowerCase();
    for (int i = 0; i < line.length(); ++i) {
      char ch = line.charAt(i);

      // check if character is any of a, e, i, o, u
      if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
        ++vowels;
      }

      // check if character is in between a to z
      else if ((ch >= 'a' && ch <= 'z')) {
        ++consonants;
      }

      // check if character is in between 0 to 9
      else if (ch >= '0' && ch <= '9') {
        ++digits;
      }

      // check if character is a white space
      else if (ch == ' ') {
        ++spaces;
      }
    }

    System.out.println("元音: " + vowels);
    System.out.println("辅音: " + consonants);
    System.out.println("数字: " + digits);
    System.out.println("空格: " + spaces);
  }
}