// CharCounter.java
// A solution to CS 5JA assignment 5, part 2, Winter 2009
// updated by cmc, 2/24/09

// Note: the javadoc comments are not required.

/**
  Provides various counts of the characters in an array.
*/
public class CharCounter {

    private char[] array;

    /**
      Only constructor associates this CharCounter object with an existing
      array of characters. The array is not copied - therefore any changes
      made to the array elements after a CharCounter object is constructed
      may affect any or all of the counts provided.
      @param theArray the array of characters to count.
    */
    public CharCounter(char[] theArray) {
        array = theArray;

        // Note: above statement is all that is required. Below is just an
        // example of the type of steps programmers take to protect their
        // code from crashing. Here it is to avoid NullPointerExceptions
        // in the methods that follow.
        if (array == null)
            array = new char[0];
    }

    /**
      Provides the total count of characters (same as the array's length).
      @return total number of characters in the array.
    */
    public int count() { return array.length; }

    /**
      Provides the count of a particular character.
      @param c the character to count.
      @return the number of occurrences of the value of c in the array.
    */
    public int count(char c) {
        int result = 0;

        for (char ac : array)
            if (ac == c) ++result;

        return result;
    }

    /**
      Provides the counts of each of an array of particular characters.
      @param c the array of characters to count.
      @return the number of occurrences (in the array referenced by this
       CharCounter object) of each value in array c, in the same order
       as the characters in c.
    */
    public int[] countEach(char[] c) {
        int results[] = new int[c.length];

        for (int i = 0; i < c.length; i++)
            results[i] = count(c[i]);

        return results;
    }

    /**
      Provides the total count of letter characters (A-Z, a-z).
      @return the number of occurrences of letter chars in the array.
    */
    public int countLetters() {
        int result = 0;

        for (char c : array)
            if ( isLetter(c) ) ++result;

        return result;
    }

    // utility method identifies a letter char
    private boolean isLetter(char c) {
        return c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z';
    }

    /**
      Provides the total count of digit characters (0-9).
      @return the number of occurrences of digit chars in the array.
    */
    public int countDigits() {
        int result = 0;

        for (char c : array)
            if ( isDigit(c) ) ++result;

        return result;
    }

    // utility method identifies a digit char
    private boolean isDigit(char c) {
        return c >= '0' && c <= '9';
    }

    /**
      Provides the total count of other characters (not letters or digits).
      @return the number of occurrences of other chars in the array.
    */
    public int countOther() {
        int result = 0;

        for (char c : array)
            if ( isOther(c) ) ++result;

        return result;
    }

    // utility method identifies a character that is neither letter nor digit
    private boolean isOther(char c) {
        return !isLetter(c) && !isDigit(c);
    }
}