C8Ex12CaptainCrunch2

public class C8Ex12CaptainCrunch2 {
	
	public static char convert(String dict, int j) {
		if (j < 13) {
			return dict.charAt(j+13);
		} else {
			return dict.charAt(j-13);
		}
	}
	
	public static String decode(String s) {
		String d = "abcdefghijklmnopqrstuvwxyz"; //dict.indexOf(n) == 13
		String D = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
		String x = "";
		int i = 0;
		int n = s.length();
		while (i < n) {
			if (s.charAt(i) == ' ') {
				x = x + " ";
			} else {
				int j = d.indexOf(s.charAt(i));
				if (j != -1) {
					x = x + convert(d, j);
				} else {
					j = D.indexOf(s.charAt(i));
					x = x + convert(D, j);
				}
			}
			
			i = i + 1;
		}
		return x;
	}

	public static void main(String[] args) {
		String s = "faiodfja";
		System.out.println(decode(s));
	}
}