ASCIIDiamond.java

public class ASCIIDiamond {
	public static void main(final String... args) {
		printDiamond(Integer.parseInt(args[0]));
	}

	public static void printDiamond(final int size) {
		if (size % 2 == 0) {
			throw new IllegalArgumentException("Size must be an odd number");
		}
		final int halfSize = (size / 2);
		for (int i = 0; i < size; i++) {
			final int offset = Math.abs(halfSize - i);
			final String outsideSpaces = nSpaces(offset);
			if (offset == halfSize) {
				System.out.println(outsideSpaces + 'x' + outsideSpaces);
			} else {
				final String insideSpaces = nSpaces(((halfSize - offset) * 2) - 1);
				System.out.println(outsideSpaces + 'x' + insideSpaces + 'x' + outsideSpaces);
			}
		}
	}

	private static String nSpaces(final int n) {
		final StringBuilder buf = new StringBuilder(n);
		for (int i = 0; i < n; i++) {
			buf.append(' ');
		}
		return buf.toString();
	}
}