初学Java 数组统计字母

public class CountLetterInArray {
  public static void main(String[] args) {
      char[] chars = createArray();
      
      System.out.println("The lowercase letters are: ");
      displayArray(chars);
      
      int[] counts = countLetters(chars);
      
      System.out.println(" ");
      System.out.println("The occurrences of each letter are: ");
      displayCounts(counts);
  }

  public static char[] createArray() {
      char[] chars = new char[100];
      for(int i=0; i<chars.length; i++) {
          chars[i] = RandomCharacter.getRandomLowerCaseLetter();
      }
      return chars;  
      
  }
  public static void displayArray(char[] chars) {
      for(int i=0; i<chars.length; i++) {
          if((i+1)%20==0)
            System.out.println(chars[i]);
          else
              System.out.print(chars[i]+" ");
      }
  }
  public static int[] countLetters(char[] chars) {
     int[] counts = new int[26];
     
     for(int i=0; i<chars.length; i++) {
         counts[chars[i]-'a']++;
     }
     return counts;
  }
  public static void displayCounts(int[] counts) {
      for(int i=0; i<counts.length; i++) {
          if((i+1)%10==0)
              System.out.println(counts[i]+" "+(char)(i+'a'));
          else
              System.out.print(counts[i]+" "+(char)(i+'a')+" ");
      }
  }
}