输出如图所示，我得到了第一行的第25个字母。

    public class RandomChar {
      public static void main(String[] args) {
        final int NUMBER_OF_CHARACTERS = 175;
        final int CHARS_PER_LINE = 25;
        for (int i = 0; i < NUMBER_OF_CHARACTERS; i++) {
            char jk = randomVariables('a', 'z');
            if (i  % CHARS_PER_LINE == 0)
                System.out.println(jk);
            else 
                System.out.print(jk);
        }
      }
      public static char randomVariables(char ch1, char ch2) {
        return (char)(ch1 + (int)(Math.random() * (ch2 - ch1 + 1)));
      }
    }