Reverse T9

public class OldPhone {

	public static void main(String[] args) {
		
		OldPhone phone = new OldPhone();
		System.out.println(phone.reverse_t9("999337777"));

	}
	
	char getCharacter(char key, int index) {
		char[][] characterMapping = new char[][] {
				{'+'},
				{' '},
				{'A', 'B', 'C'},
				{'D', 'E', 'F'},
				{'G', 'H', 'I'},
				{'J', 'K', 'L'},
				{'M', 'N', 'O'},
				{'P', 'Q', 'R', 'S'},
				{'T', 'U', 'V'},
				{'W', 'X', 'Y', 'Z'},
		};
		char[] selected = characterMapping[Integer.parseInt(String.valueOf(key))];
		return selected[index % selected.length];
	}
	
	String reverse_t9(String keys) {
		int len = keys.length(), count = 0;
		char currentChar = ' ', key;
		String result = "";
		for (int i=0; i<len; i++) {
			key = keys.charAt(i);
			if (currentChar != key) {
				if (currentChar != ' ') {
					result += String.valueOf(getCharacter(currentChar, count));
				}
				count = 0;
				currentChar = key;
			} else {
				count++;
			}
		}
		result += String.valueOf(getCharacter(currentChar, count));
		return result;
	}

}