CountLettersInArray.java

public class CountLettersInArray {
	
	/** Main method */
	public static void main(String[] agrs) {
		// Declare and create an array
		char[] chars = createArray();
		
		// Display the array
		System.out.println("The lowecase letters are: ");
		displayArray(chars);
		
		//Count the occurrences of each letter
		int[] counts = countLetters(chars);
		
		// Display counts
		System.out.println();
		System.out.println("The occurences of each letter are: ");
		displayCounts(counts);
			
	}
	
	/** Create an array of characters */
	public static char[] createArray() {
		// Declare an array of characters and create it
		char[] chars =  new char[100];
		
		//Create lowercase letters randomly and assign them to the array
		for (int i = 0; i < chars.length; i++)
			chars[i] =  RandomCharacter.getRandomLowerCaseLetter();
			
		// Return the array
		return chars;
		
	}
	
	/** Display the array of characters */
	public static void displayArray(char[] chars) {
		// Display the characters in the aray 20 on each line
		for (int i = 0; i < chars.length; i++) {
			if ((i + 1) % 20 == 0)
				System.out.println(chars[i]);
			else
				System.out.print(chars[i] + " ");
			
		}
		
	}
	
	/** Count the occurrences of  each letter */
	public static int[] countLetters(char[] chars) {
		// Declare and create an array of 26 int
		int[] counts = new int[26];
		
		// For each lowercase letter in the array, count it
		for (int i = 0; i < chars.length; i++)
			counts[chars[i] - 'a']++;
		return counts;
		
	}
	
	/** Display 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') + " ");
			
		}
		
	}
	
}
class RandomCharacter {
	public static char getRandomCharacter(char ch1, char ch2) {
		return (char)(ch1 + Math.random() * (ch2 - ch1 + 1));
		
		
	}
	
	public static char getRandomLowerCaseLetter() {
		return getRandomCharacter('a', 'z');
		
	}
	
	public static char getRandomUpperCaseLetter() {
		return getRandomCharacter('A','Z');
		
	}
	
	public static char getRandomDigitCharacter() {
		return getRandomCharacter('0', '9');
		
	}
	
	public static char getRandomCharacter() {
		return getRandomCharacter('\u0000', '\uFFFF');
		
	}

}